Kubota ZD21N-EC Workshop Manual
  1. Manuals
  2. Brands
  3. Kubota Manuals
  4. Lawn Mower
  5. ZD21N-EC
  6. Workshop manual
Kubota ZD21N-EC Workshop Manual

Kubota ZD21N-EC Workshop Manual

Hide thumbs
Table of Contents

Advertisement

Quick Links

WORKSHOP MANUAL
ZERO TURN MOWER
ZD21N-EC,ZD21-EC,ZD28-EC
KiSC issued 09, 2006 A

Advertisement

Table of Contents
loading
Need help?

Need help?

Do you have a question about the ZD21N-EC and is the answer not in the manual?

Questions and answers

Related Manuals for Kubota ZD21N-EC

Summary of Contents for Kubota ZD21N-EC

  • Page 1 WORKSHOP MANUAL ZERO TURN MOWER ZD21N-EC,ZD21-EC,ZD28-EC KiSC issued 09, 2006 A...
  • Page 2 TO THE READER This WORKSHOP MANUAL has been prepared to provide servicing personnel with information on the mechanism, service and maintenance of ZD21N-EC, ZD21-EC and ZD28-EC KUBOTA ZD Series Zero Turn Mower. It is divided into two parts, “MECHANISM” and “SERVICING” for each section except “ENGINE” section.

  • Page 3: Safety First

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM SAFETY INSTRUCTIONS SAFETY INSTRUCTIONS SAFETY FIRST This symbol, the industry’s “Safety Alert Symbol”, is used throughout this manual and on labels on the machine itself to warn of the possibility of personal injury. Read these instructions carefully.
  • Page 4 ZD21N-EC, ZD21-EC, ZD28-EC, WSM SAFETY INSTRUCTIONS SAFETY STARTING • Do not start the engine by shorting across starter terminals or bypassing the safety start switch. • Do not alter or remove any part of machine safety system. • Before starting the engine, make sure that all shift levers are in neutral positions or in disengaged positions.
  • Page 5 ZD21N-EC, ZD21-EC, ZD28-EC, WSM SAFETY INSTRUCTIONS VENTILATE WORK AREA • If the engine must be running to do some work, make sure the area is well ventilated. Never run the engine in a closed area. The exhaust gas contains poisonous carbon monoxide.

  • Page 6: Safety Decals

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM SAFETY INSTRUCTIONS SAFETY DECALS · The following safety decals are installed on the machine. If a decal becomes damaged, illegible or is not on the machine, replace it. The decal part number is listed in the parts list.
  • Page 7 ZD21N-EC, ZD21-EC, ZD28-EC, WSM SAFETY INSTRUCTIONS KiSC issued 09, 2006 A...
  • Page 8 ZD21N-EC, ZD21-EC, ZD28-EC, WSM SAFETY INSTRUCTIONS KiSC issued 09, 2006 A...

  • Page 9: Specifications

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM SPECIFICATIONS SPECIFICATIONS Model ZD21N-EC ZD21-EC ZD28-EC Maximum gross power (SAE) 15.7 kW (21 HP)* 20.9 kW (28 HP)* Model D782-E-XFM5 D1105-E2-ZD Type Indirect injection, vertical, water cooled, 4-cycle diesel engine Number of cylinders 67.0 × 73.6 mm (2.64 × 2.90 in.) 78.0 ×...
  • Page 10 60" mower deck 60" mower deck 54" mower deck 676 kg (1490.6 lbs) / With 72” mower deck Shaft drive KUBOTA 10 tooth in spline PTO clutch Wet multi discs Revolution (PTO speed) 1 speed (2540 rpm at 3000 1 speed (2530 rpm at 3200 engine rpm)
  • Page 11 ZD21N-EC, ZD21-EC, ZD28-EC, WSM DIMENSIONS DIMENSIONS KiSC issued 09, 2006 A...
  • Page 12 GENERAL KiSC issued 09, 2006 A...

  • Page 13: Table Of Contents

    GENERAL CONTENTS 1. IDENTIFICATION..................... G-1 2. GENERAL PRECAUTIONS ................G-2 3. HANDLING PRECAUTIONS FOR ELECTRICAL PARTS AND WIRING .. G-3 [1] WIRING...................... G-3 [2] BATTERY....................G-5 [3] FUSE......................G-5 [4] CONNECTOR .................... G-5 [5] HANDLING OF CIRCUIT TESTER............G-6 4. LUBRICANTS, FUEL AND COOLANT ............G-7 5.

  • Page 14: Identification

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL 1. IDENTIFICATION When contacting your local KUBOTA distributor, always specify engine serial number (3), machine serial number (2), mower serial number (4) and hour meter reading. (1) Machine Identification Plate (4) Mower Serial Number...

  • Page 15: General Precautions

    Screws, bolts and nuts should be installed in their original position to prevent reassembly errors. • When special tools are required, use KUBOTA genuine special tools. Special tools which are not frequently used should be made according to the drawings provided.

  • Page 16: Handling Precautions For Electrical Parts And Wiring

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL 3. HANDLING PRECAUTIONS FOR ELECTRICAL PARTS AND WIRING To ensure safety and prevent damage to the machine and surrounding equipment, heed the following precautions in handling electrical parts and wiring. IMPORTANT • Check electrical...
  • Page 17 ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL • Securely clamp, being careful not to damage wiring. (1) Clamp (3) Clamp • Wind Clamp Spirally (4) Welding Dent (2) Wire Harness W1011458 • Clamp wiring so that there is no twist, unnecessary sag, or excessive tension, except for movable part, where sag be required.

  • Page 18: Battery

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL [2] BATTERY • Take care not to confuse positive and negative terminal posts. • When removing battery cables, disconnect negative cable first. When installing battery cables, check for polarity and connect positive cable first.

  • Page 19: Handling Of Circuit Tester

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL • Use sandpaper to remove rust from terminals. • Repair deformed terminal. Make certain there is no terminal being exposed or displaced. (1) Exposed Terminal (3) Sandpaper (2) Bend Terminal (4) Rust W1012346 • Make certain that there is no female connector being too open.

  • Page 20: Lubricants, Fuel And Coolant

    1.9 U.S.qts. each 1.6 Imp.qts. each 0.40 L Mower gear case 0.42 U.S.qts. 0.35 Imp.qts. * Oil amount when the oil level is the upper of the oil level gauge. ** KUBOTA original transmission hydraulic fluid KiSC issued 09, 2006 A...
  • Page 21 ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL Greasing, oiling (Machine) Place No. of greasing point Capacity Type of grease Speed control lever boss Speed control lever Center pin King pin SAE multi-purpose Until grease overflows type grease Front wheel Front lift arm...

  • Page 22: Tightening Torques

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL 5. TIGHTENING TORQUES [1] GENERAL USE SCREWS, BOLTS AND NUTS Screws, bolts and nuts whose tightening torques are not specified in this Workshop Manual should be tightened according to the table below. Indication on top of...

  • Page 23: Metric Screws, Bolts And Nuts

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL [3] METRIC SCREWS, BOLTS AND NUTS Grade Property class 8.8 Property class 10.9 Unit Nominal Diameter N·m kgf·m ft-lbs N·m kgf·m ft-lbs 23.6 to 27.4 2.4 to 2.8 17.4 to 20.2 29.4 to 34.3 3.0 to 3.5...

  • Page 24: Maintenance Check List

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL 6. MAINTENANCE CHECK LIST Service interval Period Reference After page Items since every Engine oil Change G-17 100 hr every Engine oil filter Replace G-18 200 hr Transmission every Change G-21 fluid 200 hr...
  • Page 25 ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL Service interval Period Reference After page Items since every Check G-31 200 hr Radiator hose and clamp every – Replace 2 years every Check G-31 200 hr Hydraulic hose every – Replace 2 years...

  • Page 26: Check And Maintenance

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL 7. CHECK AND MAINTENANCE CAUTION • Be sure to check and service the machine on a flat place with engine shut off, the parking brake on and chock the wheels. [1] DAILY CHECK To prevent trouble from occurring, it is important to know the condition of the machine. Check the following items before starting.
  • Page 27 ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL Checking Tire Pressure WARNING To avoid personal injury: • Do not attempt to mount a tire on a rim. This should be done by a qualified person with the proper equipment. • Always maintain the correct tire pressure.
  • Page 28 ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL Checking Coolant Level CAUTION To avoid personal injury: • Do not remove the radiator cap when the engine is hot. Then loosen cap slightly to the stop to relieve any excess pressure before removing cap completely.
  • Page 29 ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL Checking and Cleaning Radiator to Prevent Overheating CAUTION To avoid personal injury: • Be sure to stop the engine and remove the key before cleaning. Daily or after every 5 hours of operation, check to be sure the radiator screen and radiator core are clean.

  • Page 30: Check Points Of Initial 50 Hours

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL [2] CHECK POINTS OF INITIAL 50 HOURS Changing Engine Oil CAUTION • Be sure to stop the engine before changing oil. 1. Start and warm up the engine for approx. 5 minutes. 2. Place an oil pan underneath the engine.
  • Page 31 IMPORTANT • To prevent serious damage to hydraulic system, the replacement filter must be a highly efficient, 10 μm filter. Use only a genuine KUBOTA filter or its equivalent. (1) Transmission Oil Filter Cartridge (2) Screw W1031068...

  • Page 32: Check Point Of Initial 100 Hours

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL [3] CHECK POINT OF INITIAL 100 HOURS Adjusting Front Axle Pivot 1. Lift up and securely block the front of the machine. 2. Measure the clearance (A) between the front axle (3) and front axle support (2).

  • Page 33: Checking Points Of Initial 200 Hours

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL [4] CHECKING POINTS OF INITIAL 200 HOURS Changing Transmission Fluid CAUTION • Be sure to stop the engine before changing the transmission fluid. 1. Place an oil pan underneath the transmission case. 2. Remove the drain plugs (1) at the bottom of the transmission case and drain the oil completely.
  • Page 34 ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL Changing Rear Axle Case Oil (RH & LH) CAUTION • Be sure to stop the engine before changing the transmission fluid. 1. Place an oil pan underneath the rear axle gear case. 2. Remove the drain plugs (1) at the bottom of the transmission case and drain the oil completely.

  • Page 35: Check Points Of Every 50 Hours

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL [5] CHECK POINTS OF EVERY 50 HOURS Checking Safety Device CAUTION To avoid personal injury: • Do not allow anyone near the machine while testing. • If the machine does not pass one of the following tests, do not operate the machine.
  • Page 36 ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL Test 6 (OPERATOR ON THE SEAT) 1. Start the engine. 2. Do not set the parking brake. 3. Shift the PTO lever (4) to “DISENGAGE” (OFF) position. 4. Grasp the motion control levers (3) and move then inward from “NEUTRAL LOCK”...
  • Page 37 ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL Greasing 1. Apply a grease to the following position as figures. CAUTION To avoid personal injury: • Be sure to stop the engine and remove the key before greasing. (1) King Pin (LH · RH) (5) Motion Control Levers (LH ·...
  • Page 38 ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL Greasing (Continued) 1. Apply a grease to the following position as figures. CAUTION To avoid personal injury: • Be sure to stop the engine and remove the key before greasing. (1) Machine Universal Joint...

  • Page 39: Check Points Of Every 100 Hours

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL Cleaning Air Cleaner Element 1. The air cleaner uses a dry element, never apply oil. 2. Do not touch the filter element except where cleaning is required. To clean the element, use clean and dry compressed air on the inside of the element.
  • Page 40 ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL Battery Charging DANGER To avoid serious injury or death: • When the battery is being activated, hydrogen and oxygen gases in the battery are extremely explosive. Keep open sparks and flames away from the battery at all times, especially when charging the battery.
  • Page 41 ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL Checking Fuel Lines And Fuel Filter CAUTION • Be sure to stop the engine and remove the key when attempting to make the following checks and changes. • Never fail to check the fuel lines periodically. The fuel lines are subject to wear and age.
  • Page 42 ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL Checking Parking Brake CAUTION To avoid personal injury: • Stop the engine and chock the wheels before checking or adjusting. • Park the machine on a hard and level surface. IMPORTANT • Wrong adjustment may cause machine damage.
  • Page 43 ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL Adjustment of brake spring play 1. Place the motion control lever to “NEUTRAL LOCK” position. 2. Be sure to chock the rear wheels. 3. Release the parking brake. 4. Loosen the lock nuts. 5. Pull the brake rod fully forward by hand and hold.

  • Page 44: Check Points Of Every 150 Hours

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL [7] CHECK POINTS OF EVERY 150 HOURS Changing Mower Gear Box Oil 1. See page G-26. W1036280 [8] CHECK POINTS OF EVERY 200 HOURS Adjusting Front Axle Pivot 1. See page G-19. W1036862 Checking Radiator Hose and Clamp NOTE •...
  • Page 45 ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL Adjusting the Motion Control Lever Pivot CAUTION To avoid personal injury: • Be sure to stop the engine and set the parking brake to “ON” before checking. 2 to 15 mm Lever free travel (A) Factory spec.

  • Page 46: Check Points Of Every 400 Hours

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL [9] CHECK POINTS OF EVERY 400 HOURS Replacing Fuel Filter 1. Disconnect the fuel hoses and loosen the filter band to replace the fuel filter (2). NOTE • If the fuel line is removed, be sure to properly bleed the fuel system.
  • Page 47 ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL Flushing Cooling System and Changing Coolant CAUTION • Do not remove the radiator cap when the engine is hot. Then loosen cap slightly to the stop to relieve any excess pressure before removing cap completely.
  • Page 48 ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL Flushing Cooling System and Changing Coolant (Continued) Anti-Freeze If coolant freezes, the cylinders and radiator can be damaged. It is necessary, if the ambient temperature falls below 0 °C (32 °F), to remove coolant mix it with anti-freeze and full the radiator with 1.

  • Page 49: Check Point Of Every 2 Years

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL [11] CHECK POINT OF EVERY 2 YEARS Replacing Hydraulic Hose 1. Replace the hose. Refer to “Checking Hydraulic Hose”. (See page G-31.) W1067327 Replacing Radiator Hose 1. Replace the hoses and clamps. Refer to “Checking Radiator Hose and Hose Clamp”. (See page G-31.)

  • Page 50: Others

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL [12] OTHERS Replacing Fuses 1. The electrical system is protected from potential damage by fuses. A blown fuse indicates that there is an overload or short somewhere in the electrical system. 2. If any of the fuses should blow, replace with a new one of the same capacity.
  • Page 51 ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL Checking Mower Blade and Replacing Mower Blade 1. Check the cutting edge of mower blade. 2. Sharpen the cutting edges, if the mower blades are as shown in figure (2). 3. Replace the mower blades, if they are as shown in figure (3).

  • Page 52: Special Tools

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL 8. SPECIAL TOOLS [1] SPECIAL TOOLS FOR ENGINE Special Use Puller Set Code No: 07916-09032 Application: Use exclusively for pushing out bearing, gears and other parts with ease. W1048293 Piston Ring Compressor Code No:...
  • Page 53 ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL Oil Pressure Tester Code No: 07916-32032 Application: Use to measure lubricating oil pressure. (1) Gauge (5) Adaptor 2 (2) Cable (6) Adaptor 3 (3) Threaded Joint (7) Adaptor 4 (4) Adaptor 1 (8) Adaptor 5...
  • Page 54 ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL Nozzle Tester Code No: 07909-31361 Application: Use to check the fuel injection pressure and spray pattern of nozzle. Measuring: 0 to 50 MPa range (0 to 500 kgf/cm , 0 to 7000 psi) W1049783...
  • Page 55 ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL Injection Pump Pressure Tester Application: Use to check fuel tightness of injection pumps. Pressure gauge full scale: More than 29.4 MPa (300 kgf/cm , 4267 psi) Copper gasket Flange (Material: Steel) Hex. nut 27 mm (1.06 in.) across the plat...
  • Page 56 ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL Bushing Replacing Tool Application: Use to press out and to press fit the bushing. 1. For small end bushing 145 mm (5.71 in.) 20 mm (0.79 in.) 100 mm (3.94 in.) 19.90 to 19.95 mm dia. (0.7835 to 0.7854 in. dia.) 21.90 to 21.95 mm dia.
  • Page 57 ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL Crankshaft Bearing 1 Replacing Tool Application: Use to press out and to press fit the crankshaft bearing [Press Out] 135 mm (5.31 in.) 72 mm (2.83 in.) 1.57 rad (40°) 10 mm (0.39 in.) 22 mm (0.87 in.)

  • Page 58: Special Tools For Machine

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM G GENERAL [2] SPECIAL TOOLS FOR MACHINE Relief Valve Pressure Tester Code No: 07916-50045 Application: This allows easy measurement of relief set pressure. (1) Gauge (07916-50322) (6) Adaptor C (PS3/8) (07916-50371) (2) Cable (07916-50331) (7) Adaptor D (PT1/8) (07916-50381)
  • Page 59 ENGINE KiSC issued 09, 2006 A...
  • Page 60 MECHANISM CONTENTS 1. FUEL SYSTEM ..................... 1-M1 [1] GOVERNOR .................... 1-M1 KiSC issued 09, 2006 A...
  • Page 61 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE 1. FUEL SYSTEM [1] GOVERNOR The governor system is a mechanical governor that used the flyweight (1). The flyweight (1) is mounted on the governor shaft that rotates at the same speed as the crankshaft.
  • Page 62 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Overloaded Operation The amount of the movement of the fork lever comp. is limited with the fuel limitation bolt (10) and can not be moved in the direction of the fuel increase. As overload reduces the centrifugal force of the...
  • Page 63 SERVICING CONTENTS 1. TROUBLESHOOTING ..................1-S1 2. SERVICING SPECIFICATIONS[D782-E-XFM5] ...........1-S5 [1] ENGINE BODY ..................1-S5 [2] LUBRICATING SYSTEM .................1-S9 [3] COOLING SYSTEM.................1-S9 [4] FUEL SYSTEM ..................1-S10 3. SERVICING SPECIFICATIONS[D1105-E2-ZD] ..........1-S11 [1] ENGINE BODY ..................1-S11 [2] LUBRICATING SYSTEM ...............1-S15 [3] COOLING SYSTEM................1-S15 [4] FUEL SYSTEM ..................1-S16 4.

  • Page 64: Troubleshooting

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE 1. TROUBLESHOOTING Reference Symptom Probable Cause Solution Page Engine Does Not • No fuel Replenish fuel – Start • Air in the fuel system Bleed fuel system – • Water in the fuel system Change fuel and –...
  • Page 65 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Reference Symptom Probable Cause Solution Page Engine Revolution Is • Fuel filter clogged or dirty Replace fuel filter G-33 Not Smooth • Air cleaner clogged Clean or replace air G-26 cleaner element. • Fuel leak due to loose injection pipe retaining...
  • Page 66 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Reference Symptom Probable Cause Solution Page Fuel Mixed into • Injection pump’s plunger worn Replace pump 1-S31, S35 Lubricant Oil element or injection pump • Deficient nozzle injection Repair or replace 1-S29, S74 nozzle • Injection pump broken...
  • Page 67 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Reference Symptom Probable Cause Solution Page Engine Overheated • Engine oil insufficient Replenish engine oil G-17 • Fan belt broken or tensioned improperly Replace fan belt or G-28 adjust fan belt tension • Coolant insufficient Replenish coolant –...

  • Page 68: Servicing Specifications[D782-E-Xfm5]

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE 2. SERVICING SPECIFICATIONS [D782-E-XFM5] [1] ENGINE BODY Item Factory Specification Allowable Limit Cylinder Head Surface Flatness – 0.05 mm 0.0020 in. Top Clearance 0.50 to 0.70 mm – 0.0197 to 0.0276 in. Compression Pressure 2.84 to 3.24 MPa 2.26 MPa...
  • Page 69 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE ENGINE BODY (Continued) Item Factory Specification Allowable Limit Valve Spring Free Length 31.3 to 31.8 mm 28.4 mm 1.232 to 1.252 in. 1.118 in. Setting Load 64.7 N 54.9 N 6.6 kgf 5.6 kgf 14.6 lbs 12.3 lbs...
  • Page 70 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE ENGINE BODY (Continued) Item Factory Specification Allowable Limit Timing Gear Crank Gear to Idle Gear Backlash 0.043 to 0.124 mm 0.15 mm 0.00169 to 0.00488 in. 0.0059 in. Idle Gear to Cam Gear Backlash 0.047 to 0.123 mm 0.15 mm...
  • Page 71 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE ENGINE BODY (Continued) Item Factory Specification Allowable Limit Crankshaft Alignment – 0.02 mm 0.0008 in. Crankshaft Journal to Crankshaft Bearing Oil Clearance 0.034 to 0.106 mm 0.20 mm 0.00134 to 0.00417 in. 0.0079 in. Crankshaft Journal O.D.

  • Page 72: Lubricating System

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE [2] LUBRICATING SYSTEM Item Factory Specification Allowable Limit Engine Oil Pressure At Idle Speed More than 49 kPa – 0.5 kgf/cm 7 psi At Rated Speed 196 to 441 kPa 147 kPa 2.0 to 4.5 kgf/cm 1.5 kgf/cm...

  • Page 73: Fuel System

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE [4] FUEL SYSTEM Item Factory Specification Allowable Limit Injection Pump Injection Timing 0.33 to 0.37 rad – 19.0 to 21.0° before T.D.C. Pump Element Fuel Tightness – 14.7 MPa 150 kgf/cm 2130 psi Delivery Valve Fuel Tightness –...

  • Page 74: Servicing Specifications[D1105-E2-Zd]

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE 3. SERVICING SPECIFICATIONS [D1105-E2-ZD] [1] ENGINE BODY Item Factory Specification Allowable Limit Cylinder Head Surface Flatness – 0.05 mm 0.0020 in. Top Clearance 0.55 to 0.70 mm – 0.0217 to 0.0276 in. Compression Pressure (When Cranking with Starting Motor) 2.84 to 3.24 MPa...
  • Page 75 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE ENGINE BODY (Continued) Item Factory Specification Allowable Limit Valve Spring Free Length 37.0 to 37.5 mm 36.5 mm 1.457 to 1.476 in. 1.437 in. Setting Load 117.6 N 100.0 N 12.0 kgf 10.2 kgf 26.4 lbs 22.5 lbs...
  • Page 76 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE ENGINE BODY (Continued) Item Factory Specification Allowable Limit Timing Gear Crank Gear to Idle Gear Backlash 0.032 to 0.115 mm 0.15 mm 0.0013 to 0.0045 in. 0.0059 in. Idle Gear to Cam Gear Backlash 0.036 to 0.114 mm 0.15 mm...
  • Page 77 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE ENGINE BODY (Continued) Item Factory Specification Allowable Limit Crankshaft Journal to Crankshaft Bearing Oil Clearance 0.034 to 0.114 mm 0.20 mm 0.00134 to 0.00449 in. 0.0079 in. Crankshaft Journal O.D. 47.934 to 47.950 mm –...

  • Page 78: Lubricating System

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE [2] LUBRICATING SYSTEM Item Factory Specification Allowable Limit Engine Oil Pressure At Idle Speed More than 49 kPa – 0.5 kgf/cm 7 psi At Rated Speed 196 to 441 kPa 147 kPa 2.0 to 4.5 kgf/cm 1.5 kgf/cm...

  • Page 79: Fuel System

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE [4] FUEL SYSTEM Item Factory Specification Allowable Limit Injection Pump Injection Timing 0.33 to 0.37 rad – 19.0 to 21.0° before T.D.C. Pump Element Fuel Tightness – 14.7 MPa 150 kgf/cm 2133 psi Delivery Valve...

  • Page 80: Tightening Torques

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE 4. TIGHTENING TORQUES Tightening torques of screws, bolts and nuts on the table below are especially specified. (For general use screws, bolts and nuts : See page G-9.) Item Size × Pitch N·m kgf·m ft-lbs M6 ×...
  • Page 81 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE [D1105-E2-ZD] Item Size × Pitch N·m kgf·m ft-lbs M10 × 1.25 Air cleaner stay nut 48.1 to 55.9 4.9 to 5.7 35.4 to 41.2 M6 × 1.0 * Bearing case cover screw 9.8 to 11.3 1.00 to 1.15...

  • Page 82: Checking, Disassembling And Servicing

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE 5. CHECKING, DISASSEMBLING AND SERVICING [1] SEPARATING ENGINE (1) Disassembling and Assembling Draining Engine Oil 1. Park the machine on level ground. 2. Start and warm up the engine for approx. 5 minutes. 3. Place an oil pan underneath the engine.
  • Page 83 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Draining Coolant CAUTION • Never open the radiator cap while operating or immediately after stopping. Otherwise, hot water will spout out from the radiator. Wait for more than ten minutes to cool the radiator, before opening the cap.
  • Page 84 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE [ZD21N · ZD21] Battery CAUTION • When disconnecting the battery cables, disconnect the negative cable from the battery first. When connecting, connect the positive cable to the battery first. 1. Remove the battery cover (1).
  • Page 85 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Engine Disassembly 1. Remove the universal joint mounting screws (1). 2. Disconnect the universal joint (2) from fun drive pulley. 3. Pull out the snap pins from the radiator. 4. Remove the engine mounting nuts.
  • Page 86 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE [ZD28] Battery and Bonnet CAUTION • When disconnecting the battery cables, disconnect the negative cable from the battery first. When connecting, connect the positive cable to the battery first. 1. Remove the battery cover (1).
  • Page 87 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Dynamo, Fan Belt and Muffler 1. Disconnect the radiator hoses and separate the radiator (1) with recovery tank (5) from engine assembly. 2. Remove the cooling fan (2) and fan pulley. 3. Remove the dynamo (6) and fan belt (7).
  • Page 88 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE [2] ENGINE BODY (1) Checking and Adjusting Compression Pressure 1. Run the engine until it is warmed up. 2. Stop the engine. 3. Disconnect the 2P connector from the fuel pump. 4. Remove the air cleaner, the muffler and all injection nozzles.
  • Page 89 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Top Clearance 1. Remove the cylinder head (Do not attempt to remove the cylinder head gasket completely). 2. Bring the piston to its top dead center fasten 1.5 mm dia. 5 to 7 mm long fuse wires to 3 to 4 spots on the piston top with grease so as to avoid the intake and exhaust valves and the combustion chamber ports.
  • Page 90 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Valve Clearance IMPORTANT • The valve clearance must be checked and adjusted when engine is cold. 1. Remove the cylinder head cover and the glow plugs. 2. Align the “1TC” mark (1) on the flywheel and alignment mark (2) on the rear end plate so that the No.
  • Page 91 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE (2) Disassembling and Assembling (A) Cylinder Head and Valves Dynamo, Fan Belt and Muffler 1. Disconnect the radiator hoses and separate the radiator (3) with recovery tank (8) from engine assembly. 2. Remove the cooling fan (4) and fan pulley.
  • Page 92 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Nozzle Holder Assembly and Glow Plug 1. Remove the overflow pipe assembly (5). 2. Remove the nozzle holder assemblies (2) using a 21 mm deep socket wrench. 3. Remove the copper gasket and heat seal (3).
  • Page 93 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Cylinder Head 1. Loosen the pipe clamp, and remove the water return pipe. 2. Remove the cylinder head bolt in the order of (14) to (1). 3. Lift up the cylinder head to detach. 4. Remove the cylinder head gasket and O-ring for carbon sheet gasket.
  • Page 94 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE (B) Timing Gears, Fuel Camshaft and Camshaft [D782-E-XFM5] Injection Pump and Speed Control Plate 1. Remove the socket head screws and nuts, and remove the injection pump (3). 2. Remove the screws and separate the speed control plate (2), taking care not to damage the spring (4).
  • Page 95 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Gear Case 1. Remove the screw (1). 2. Disconnect the start spring (2) in the speed control plate mounting hole. 3. Remove the gear case (3). (When reassembling) • Apply a liquid gasket (Three Bond 1215 or equivalent) to both sides of the gear case gasket (4).
  • Page 96 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Fuel Camshaft 1. Remove the screws and draw out the camshaft with the gear on 2. Remove the retaining plate (1). 3. Remove the screws, then draw out the injection pump gear (2) and fuel camshaft (3) with the governor fork assembly.
  • Page 97 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Water Pump 1. Remove the water pump flange. (When reassembling) • Before installing the water pump flange gasket, apply liquid gasket (Three Bond 1215 or equivalent) to the both side. W1035410 Gear Case 1. Remove the gear case.
  • Page 98 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Injection Pump 1. Remove the injection pump mounting screws and nuts. 2. Disconnect the start spring (4) on the thrust lever side (5). 3. Align the control rack pin (2) with the notch (1) on the crankcase, and remove the injection pump (3).
  • Page 99 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Governor Shaft 1. Remove the pump cover. 2. Remove the external snap ring (1) from the governor shaft (2). 3. Pull out the governor shaft (2). (When reassembling) • Make sure assembling the external snap ring of the governor shaft.
  • Page 100 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE (D) Connecting Rod and Piston Oil Pan and Oil Strainer 1. Remove the oil pan (4). 2. Remove the oil strainer (3). (When reassembling) • Install the oil strainer, using care not to damage the O-ring (1).
  • Page 101 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Piston 1. Turn the flywheel and bring the No. 1 piston to the top dead center. 2. Pull out the piston upward by lightly tapping it from the bottom of the crankcase with the grip of a hammer.
  • Page 102 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Piston Ring and Connecting Rod 1. Remove the piston rings using a piston ring tool. 2. Remove the piston pin (1), and separate the connecting rod (7) from the piston (2). (When reassembling) • When installing the rings, assemble the rings so that the manufacturer’s mark (12) near the gap faces the top of the piston.
  • Page 103 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE (E) Crankshaft Flywheel 1. Lock the flywheel not to turn using flywheel stopper. 2. Remove the flywheel screws, except for two which must be loosened and left as they are. 3. Set a flywheel puller (Code No: 07916-32011), and remove the flywheel.
  • Page 104 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Crankshaft 1. Remove the main bearing case screw 2 (1). (D1105) 2. Pull out the crankshaft assembly. (D782) 3. Turn the crankshaft to set the crank pin of the third cylinder to the bottom dead center. Then draw out the crankshaft until the crank pin of the second cylinder comes to the center of the third cylinder.
  • Page 105 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE (3) Servicing (A) Cylinder Head and Valve Cylinder Head Surface Flatness 1. Clean the cylinder head surface. 2. Place a straightedge on the cylinder head’s four sides and two diagonal as shown in the figure.
  • Page 106 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Valve Recessing 1. Clean the cylinder head surface, valve face and valve seat. 2. Insert the valve into the valve guide. 3. Measure the valve recessing with a depth gauge. 4. If the measurement exceeds the allowable limit, replace the valve.
  • Page 107 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Replacing Valve Guide (When removing) 1. Press out the used valve guide using a valve guide replacing tool. (When installing) 1. Clean a new valve guide and valve guide bore, and apply engine oil to them.
  • Page 108 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Correcting Valve and Valve Seat NOTE • Before correcting the valve and seat, check the valve stem and the I.D. of the valve guide section, and repair them if necessary. • After correcting the valve seat, be sure to check the valve recessing.
  • Page 109 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Free Length and Tilt of Valve Spring 1. Measure the free length (A) of valve spring with venire calipers. If the measurement is less than the allowable limit, replace it. 2. Put the valve spring on a surface plate, place a square on the side of the valve spring.
  • Page 110 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Oil Clearance between Rocker Arm and Rocker Arm Shaft 1. Measure the rocker arm shaft O.D. with an outside micrometer. 2. Measure the rocker arm I.D. with an inside micrometer, and then calculate the oil clearance.
  • Page 111 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Oil Clearance between Tappet and Tappet Guide Bore 1. Measure the tappet O.D. with an outside micrometer. 2. Measure the I.D. of the tappet guide bore with a cylinder gauge, and calculate the oil clearance.
  • Page 112 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE (B) Timing Gears, Camshaft and Fuel Camshaft Timing Gear Backlash 1. Set a dial indicator (lever type) with its tip on the gear tooth. 2. Move the gear to measure the backlash, holding its mating gear.
  • Page 113 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Idle Gear Side Clearance 1. Set a dial indicator with its tip on the idle gear. 2. Measure the side clearance by moving the idle gear to the front and rear. 3. If the measurement exceeds the allowable limit, replace the idle gear collar.
  • Page 114 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Cam Height 1. Measure the height of the cam at its highest point with an outside micrometer. 2. If the measurement is less than the allowable limit, replace the camshaft. [D782] 26.88 mm Factory spec.
  • Page 115 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Oil Clearance between Idle Gear Shaft and Idle Gear Bushing 1. Measure the idle gear shaft O.D. with an outside micrometer. 2. Measure the idle gear bushing I.D. with an inside micrometer, and calculate the oil clearance.
  • Page 116 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE (C) Piston and Connecting Rod Piston Pin Bore I.D. 1. Measure the piston pin bore I.D. in both the horizontal and vertical directions with a cylinder gauge. 2. If the measurement exceeds the allowable limit, replace the piston.
  • Page 117 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Replacing Small End Bushing (When removing) 1. Press out the used bushing using a small end bushing replacing tool. (When installing) 1. Clean a new small end bushing and bore, and apply engine oil to them.
  • Page 118 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Clearance between Piston Ring and Piston Ring Groove 1. Clean the rings and the ring grooves, and install each ring in its groove. 2. Measure the clearance between the ring and the groove with a feeler gauge.
  • Page 119 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Crankshaft Side Clearance 1. Set a dial indicator with its tip on the end of the crankshaft. 2. Measure the side clearance by moving the crankshaft to the front and rear. 3. If the same size bearing is useless because of the crankshaft journal wear, replace it with an oversize one referring to the table and the figure.
  • Page 120 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Crankshaft Alignment 1. Support the crankshaft with V blocks on the surface plate at both end journals. 2. Set a dial indicator with its tip on the intermediate journal. 3. Measure the crankshaft alignment. 4. If the measurement exceeds the allowable limit, replace the crankshaft.
  • Page 121 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Oil Clearance between Crankpin and Crankpin Bearing (Continued) (Reference) • Undersize crankpin bearing [D782] Undersize Bearing Code Number Marking 0.2 mm Crankpin bearing 02 15861-22970 020 US 0.008 in. 0.4 mm Crankpin bearing 04 15861-22980 040 US 0.016 in.
  • Page 122 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Oil Clearance between Crankshaft Journal and Crankshaft Bearing 1 (To be continued) 1. Measure the O.D. of the crankshaft front journal with an outside micrometer. 2. Measure the I.D. of the crankshaft bearing 1 with an inside micrometer, and calculate the oil clearance.
  • Page 123 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Oil Clearance between Crankshaft Journal and Crankshaft Bearing 1 (Continued) (Reference) • Undersize crankshaft bearing 1 [D782] Undersize Bearing Code Number Marking 0.2 mm Crankshaft bearing 1 02 15861-23910 020 US 0.008 in. 0.4 mm...
  • Page 124 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Replacing Crankshaft Bearing 1 (When removing) 1. Press out the used crankshaft bearing 1 using a crankshaft bearing 1 replacing tool. (When installing) 1. Clean a new crankshaft bearing 1 and crankshaft journal bore, and apply engine oil to them.
  • Page 125 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Oil Clearance between Crankshaft Journal and Crankshaft Bearing 2 and Crankshaft Bearing 3 (To be continued) 1. Put a strip of plastigage (Code No. 07909-30241) on the center of the journal. 2. Install the bearing case and tighten the bearing case screws 1 to the specified torque, and remove the bearing case again.
  • Page 126 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Oil Clearance between Crankshaft Journal and Crankshaft Bearing 2 and Crankshaft Bearing 3 (Continued) (Reference) • Undersize crankshaft bearing 2 and 3 [D782] Undersize Bearing Code Number Marking Crankshaft bearing 2 02 15694-23930 020 US 0.2 mm...
  • Page 127 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Cylinder Wear 1. Measure the cylinder liner I.D. at the six positions (see figure) with a cylinder gauge to find the maximum and minimum I.D.’s. 2. Get the difference (Maximum wear) between the maximum and the minimum I.D.’s.
  • Page 128 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Correcting Cylinder 1. When the cylinder is worn beyond the allowable limit, bore and hone it to the specified dimension. [D782] 67.250 to 67.269 mm Factory spec. 2.64764 to 2.64839 in. Oversized cylinder liner I.D.
  • Page 129 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE [3] LUBRICATING SYSTEM (1) Checking Engine Oil Pressure 1. Remove the engine oil pressure switch, and set a oil pressure tester (Code No. 07916-32032). (Adapter screw size : PT 1/8) 2. Start the engine. After warming up, measure the oil pressure of both idling and rated speeds.
  • Page 130 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Clearance between Rotor and Cover 1. Put a strip of plastigage (Code No. 07909-30241) onto the rotor face with grease. 2. Install the cover and tighten the screws. 3. Remove the cover carefully, and measure the amount of the flattening with the scale and get the clearance.
  • Page 131 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE [4] COOLING SYSTEM (1) Checking and Adjusting (A) Fan Belt Fan Belt Tension 1. Measure the deflection (A), depressing the belt halfway between the fan drive pulley and alternator pulley at specified force (98 N, 10 kgf, 22 lbs).
  • Page 132 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE (B) Radiator CAUTION • When removing the radiator cap, wait at least ten minutes after the engine has stopped and cooled down. Otherwise, hot water may gush out, scalding nearby people. Radiator Water Leakage 1. Pour a specified amount of water into the radiator.
  • Page 133 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE (2) Disassembling and Assembling Thermostat Assembly 1. Remove the thermostat cover mounting screws, and remove the thermostat cover (1). 2. Remove the thermostat assembly (3). (When reassembling) • Apply a liquid gasket (Three Bond 1215 or equivalent) only at the thermostat cover side of the gasket (2).
  • Page 134 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE [5] FUEL SYSTEM (1) Checking and Adjusting (A) Injection Pump Injection Timing 1. Remove the bonnet and air cleaner. 2. Remove the muffler. 3. Remove the injection pipes and glow plugs. 4. Engage the parking brake.
  • Page 135 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE Fuel Tightness of Pump Element 1. Remove the bonnet and air cleaner. 2. Remove the muffler. 3. Disconnect the accelerator wire. 4. Remove the air cleaner stay. 5. Remove the injection pipes and glow plugs.
  • Page 136 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE (B) Injection Nozzle CAUTION • Check the injection pressure and condition after confirming that there is nobody standing in the direction the fume goes. If the fume from the nozzle directly contacts the human body, cells may be destroyed and blood poisoning may be caused.
  • Page 137 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ENGINE (2) Disassembling and Assembling (A) Injection Nozzle Nozzle Holder 1. Secure the nozzle retaining nut (7) with a vise. 2. Remove the nozzle holder (1), and take out parts inside. (When reassembling) • Assemble the nozzle in clean fuel oil.
  • Page 138 TRANSAXLE KiSC issued 09, 2006 A...
  • Page 139 MECHANISM CONTENTS 1. STRUCTURE ....................2-M1 2. TRAVELLING SYSTEM ................2-M2 [1] HYDROSTATIC TRANSMISSION ............2-M2 (1) Structure .................... 2-M2 (2) Pump and Motor ................2-M3 (3) Check Valve and High Pressure Relief Valve ........2-M4 (4) Oil Flow ....................2-M5 (5) Power Trains Operation ..............

  • Page 140: Structure

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE 1. STRUCTURE (1) Hydrostatic Transmission (3) Final Reduction Gear Section (4) Parking Brake Section (5) Bevel Gear Section (2) PTO Section KiSC issued 09, 2006 A 2-M1...

  • Page 141: Travelling System

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE 2. TRAVELLING SYSTEM [1] HYDROSTATIC TRANSMISSION (1) Structure (1) Lubricating Orifice (6) Cradle Bearing (11) Ball Bearing (16) Check Valve Spring (2) Bearing (7) Slot Guide (12) Thrust Ball Bearing (17) Relief Valve Spring (3) Pump Shaft...

  • Page 142: Pump And Motor

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE (2) Pump and Motor (1) Swashplate (4) Oil (7) Swashplate (A) Pump (2) Piston (5) Cylinder (B) Motor (3) Cylinder (6) Piston Pump and motor cylinder, each containing pistons, are connected by lines. Cylinders and lines are filled with oil.

  • Page 143: Check Valve And High Pressure Relief Valve

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE (3) Check Valve and High Pressure Relief Valve The check and high-pressure relief valve consists of pressure poppet (2), check valve seat (1), relief valve spring (3), spring guide (4) and check valve spring (5).

  • Page 144: Oil Flow

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE (4) Oil Flow (A) ZD21N · ZD21 (1) Oil Strainer (5) Regulator Valve (8) Check and High Pressure (11) Swashplate (2) Transmission Case (6) PTO Clutch Relief Valve (12) Piston (3) Hydraulic Pump (7) Oil Filter Cartridge...
  • Page 145 ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE (B) ZD28 (1) Oil Strainer (5) Control Valve (9) Check and High Pressure (12) Swashplate (2) Transmission Case (6) Regulator Valve Relief Valve (13) Piston (3) Hydraulic Pump (7) PTO Clutch (10) Lubricating Orifice (14) Cylinder Block (Motor)

  • Page 146: Power Trains Operation

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE (5) Power Trains Operation (1) Check and High Pressure (1)-2 Check Valve (3) Regulator Valve (6) Pump Relief Valve (1)-3 Neutral Orifice (4) Motor (7) Hydraulic Pump (1)-1 Relief Valve (2) Oil Filter (5) Lubricating Orifice...

  • Page 147: Control Linkage

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE (6) Control Linkage (1) Motion Control Lever (3) Trunnion Arm (5) Speed Shaft (6) Neutral Slot (2) Speed Control Rod (4) Speed Limit Spring The motion control lever (1) and the trunnion shaft of variable swashplate are linked with the speed shaft (5), speed control rod (2) and the trunnion arm (3).

  • Page 148: Final Reduction Gear Section

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE (7) Final Reduction Gear Section As for this machine, power is transmitted from the 12T gear (1) on the HST motor shaft to the rear axle (5) through 53T gear, 14T gear shaft and 57T gear.

  • Page 149: Pto System

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE (8) PTO System (A) PTO Clutch and Valve (1) 34T Gear (ZD21N · ZD21) (5) Regulator Valve (11) PTO Shaft (A) From Hydraulic Pump 33T Gear (ZD28) (6) Rear Cover (12) PTO Brake Plate (B) To Hydrostatic Transmission...
  • Page 150 ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE Regulator Valve This machine is controlled with the regulator valve so that the oil sent from the hydraulic pump may become the setting pressure. And the oil flows into PTO clutch and hydrostatic transmission. (Reference) •...
  • Page 151 ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE (B) Parking Brake (1) Parking Brake Lever (4) Parking Brake Spring (6) Parking Brake Rod (8) Brake Drum (2) Parking Brake Lock Pedal (5) Return Spring (7) Brake Assembly (9) Brake Shoe (3) Brake Plate The parking brake is composed of parking brake lever (1), parking brake lock pedal (2), brake plate (3), parking brake rod (6) and brake assembly (7).
  • Page 152 SERVICING CONTENTS 1. TROUBLESHOOTING ..................2-S1 2. SERVICING SPECIFICATIONS ..............2-S3 3. TIGHTENING TORQUES ................2-S4 4. CHECKING AND ADJUSTING ..............2-S5 5. DISASSEMBLING AND ASSEMBLING ............2-S11 [1] SEPARATING TRANSAXLE..............2-S11 6. SERVICING ....................2-S22 [1] HYDROSTATIC TRANSMISSION ............2-S22 [2] TRANSMISSION CASE .................2-S24 KiSC issued 09, 2006 A...

  • Page 153: Troubleshooting

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE 1. TROUBLESHOOTING Reference Symptom Probable Cause Solution Page Vehicle Will Not Stop • Improper neutral adjustment Adjust neutral 2-S5 in Neutral Position • Improper speed change rod adjustment Adjust 2-S5 Vehicle Jerky and • Transmission oil insufficient...
  • Page 154 ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE TRAVELLING GEAR SHIFT SECTION Reference Symptom Probable Cause Solution Page Noise from • Transmission oil insufficient Refill – Transmission • Gear worn or broken Replace – • Bearings worn Replace 2-S22 W1014322 PTO SECTION PTO Clutch Slip •...

  • Page 155: Servicing Specifications

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE 2. SERVICING SPECIFICATIONS Item Factory Specification Allowable Limit Regulator Valve Setting pressure 0.50 to 0.69 MPa – 5.0 to 7.0 kgf/cm 71.2 to 99.6 psi PTO Clutch Operating 0.50 to 0.69 MPa – pressure 5.0 to 7.0 kgf/cm 71.2 to 99.6 psi...

  • Page 156: Tightening Torques

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE 3. TIGHTENING TORQUES Tightening torques of screws, bolts and nuts on the table below are especially specified. (For general use screws, bolts and nuts: See page G-9.) Item N·m kgf·m ft-lbs Motion control lever mounting bolt and nut 17.7 to 20.6...

  • Page 157: Checking And Adjusting

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE 4. CHECKING AND ADJUSTING Checking Neutral 1. Park machine safely. 2. Set the motion control levers are in the NEUTRAL position. 3. Move the PTO lever to OFF position and apply the parking brake. 4. With the operator on the seat and start the engine.
  • Page 158 ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE Checking Creep in Forward CAUTION To avoid personal injury: • Park the machine on a hard and level surface. • If it is necessary to run engine in an enclosed area, use a gas tight exhaust pipe extension to remove the fumes.
  • Page 159 ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE Adjusting Maximum Speed CAUTION To avoid personal injury: • Park the machine on a hard and level surface. • If it is necessary to run engine in an enclosed area, use a gas tight exhaust pipe extension to remove the fumes.
  • Page 160 ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE Checking Motion Control Lever Alignment CAUTION • When checking, park the tractor on flat ground, apply the parking brake. 1. Check the gap (A) and space (B) between the motion control levers, at the maximum forward position.
  • Page 161 ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE Checking Hydrostatic Transmission CAUTION • When checking, park the machine on flat ground, apply the parking brake. • Sit on operator’s seat for checking. 1. After worming up the machine, apply the parking brake and set the stop wood (chock) to the rear wheels.
  • Page 162 ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE PTO Clutch Operating Pressure (Hydrostatic Transmission Charge Pressure) CAUTION • When checking, park the tractor on flat ground, apply the parking brake. 1. Remove the eye joint bolt (1), then install the adaptor cable and pressure gauge.

  • Page 163: Disassembling And Assembling

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE 5. DISASSEMBLING AND ASSEMBLING [1] SEPARATING TRANSAXLE Draining Transmission Fluid CAUTION • Be sure to stop the engine before changing the transmission fluid. 1. Place an oil pan underneath the transmission case. 2. Remove the drain plugs (1) at the bottom of the transmission case and drain the oil completely.
  • Page 164 ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE Seat, Motion control lever, Fenders and Others 1. Remove the motion control lever boot (RH) (9) and motion control lever (RH) (10). 2. Disconnect the wire harness from fender (RH) and remove the fender (RH) (8).
  • Page 165 ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE Upper Frame 1. Disconnect the connectors from limit switches. 2. Disconnect the connectors from regulator (2) and combination box (3), then remove the wire harness (1) from upper frame. 3. Remove the PTO rod, lift rod and disconnect the throttle wire.
  • Page 166 ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE Universal Joint [ZD28] 1. Remove the propeller shaft (1). 2. Remove the clamp for fuel hoses, wire harness and delivery hose (4). 3. Disconnect the delivery hose (4) from oil cooler (3). 4. Disconnect the delivery pipe from oil cooler and remove the delivery pipe (2).
  • Page 167 ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE Hydraulic Pipes 1. Remove the delivery hose (4) and pipe as a unit. 2. Remove the hydraulic pipes. (When reassembling) • Take care not to damage the O-rings. NOTE • When installing the O-ring and coller (3), note the position of O-ring onto the delivery pipe shown in the figure.
  • Page 168 ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE Center Section 1. Remove the center section mounting hex. socket head screws. 2. Tap the center section (1) with soft hammer and separate the center section (1) from the HST housing (2). (When reassembling) • Cover the splines of each shaft with thin tape to protect the sealing lip of the oil seals.
  • Page 169 ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE Cylinder Block Assembly and Thrust Ball Bearing 1. Lay the housing on its side. 2. Slide out the cylinder bloke assembly (pump) (1). 3. Slide out the cylinder block assembly (motor) (3) with the motor shaft (2).
  • Page 170 ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE Slot Guide and Cradle Bearing 1. Remove the slot guide (2) from the trunnion arm (3). 2. Remove the cradle bearing (1) from the housing. (1) Cradle Bearing (3) Trunnion Arm (2) Slot Guide W1031110 Pump Shaft 1.
  • Page 171 ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE Disassembling PTO Clutch Assembly 1. Remove the bearing (1) and 43T gear (2). 2. Tap out the PTO clutch shaft (3) from clutch case (8). 3. Remove the internal snap ring (16), then remove the pressure plate (15), clutch disc and clutch plate (17).
  • Page 172 ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE Regulator Valve 1. Remove the internal snap ring (5), plug (4), spring (3) and poppet (2). (When reassembling) • Take care not to damage the O-rings. (1) Center Cover Assembly (4) Plug (2) Poppet (5) Internal Snap Ring...
  • Page 173 ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE Brake Shaft and Rear Axle 1. Remove the brake cover assembly (1). 2. Remove the external snap ring (3) and brake drum (4). 3. Remove the ball bearing (6). 4. Remove the 57T gear (7) and brake shaft (8).

  • Page 174: Servicing

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE 6. SERVICING [1] HYDROSTATIC TRANSMISSION Center Section 1. Check the surface (1) of center section for scratches or wear. If deep scratch or excessive wear is found, replace the hydrostatic transmission assembly. (1) Surface W1018716 Check and High Pressure Relief Valve 1.
  • Page 175 ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE Pump Shaft 1. Check the seal surface (4), the bearing surface (3) and the ball bearing (1). 2. If the shaft is rough or grooved, replace it. 3. If the ball bearing is worn, replace it.

  • Page 176: Transmission Case

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE [2] TRANSMISSION CASE Checking Bearing 1. Hold the inner race, and push and pull the outer race in all directions to check for wear and roughness. 2. Apply transmission fluid to the bearing, and hold the inner race.
  • Page 177 ZD21N-EC, ZD21-EC, ZD28-EC, WSM TRANSAXLE Correcting of Tooth Contact 1. Proper contact. • No adjustment. W1028600 2. Correcting of the heel contact and shallow contact. • It is confirmed whether there is a shim (3). • The 16T bevel gear (5) can be moved to backward by doing to add the shim (3) when not is.

  • Page 178: Front Axle

    FRONT AXLE KiSC issued 09, 2006 A...
  • Page 179 MECHANISM CONTENTS 1. STRUCTURE ....................3-M1 KiSC issued 09, 2006 A...
  • Page 180 ZD21N-EC, ZD21-EC, ZD28-EC, WSM FRONT AXLE 1. STRUCTURE (1) Cap (3) Taper Roller Bearing (5) Lift Up Adjuster (7) Slotted Nut (2) Taper Roller Bearing (4) Wheel Bracket (6) Front Axle (8) Center Pin The front axle is constructed as shown above. The shape of the front axle is relatively simple, and the front axle is supported at its center with the center pin (8), so that steering operation is stable even on uneven grounds in a grass field.
  • Page 181 SERVICING CONTENTS 1. TROUBLESHOOTING ..................3-S1 2. SERVICING SPECIFICATIONS ..............3-S2 3. TIGHTENING TORQUES ................3-S3 4. CHECKING, DISASSEMBLING AND SERVICING........3-S4 [1] CHECKING AND ADJUSTING ...............3-S4 [2] DISASSEMBLING AND ASSEMBLING..........3-S5 (1) Separating Front Wheel and Wheel Bracket........3-S5 KiSC issued 09, 2006 A...

  • Page 182: Troubleshooting

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM FRONT AXLE 1. TROUBLESHOOTING Reference Symptom Probable Cause Solution Page Front Wheels • Clearance between center pin and front axle Replace – Wander to Right or excessive Left • Force of the lock nut which tighten the wheel...

  • Page 183: Servicing Specifications

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM FRONT AXLE 2. SERVICING SPECIFICATIONS Item Factory Specification Allowable Limit Front Axle End Play Clearance 0 to 0.2 mm 0.5 mm 0 to 0.008 in. 0.02 in. W1013874 KiSC issued 09, 2006 A 3-S2...

  • Page 184: Tightening Torques

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM FRONT AXLE 3. TIGHTENING TORQUES Tightening torques of screws, bolts and nuts on the table below are especially specified. (For general use screws, bolts and nuts: See page G-9.) Item N·m kgf·m ft-lbs Wheel bolt and lock nut 20 to 25 2.04 to 2.55...

  • Page 185: Checking, Disassembling And Servicing

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM FRONT AXLE 4. CHECKING, DISASSEMBLING AND SERVICING [1] CHECKING AND ADJUSTING Adjusting Front Axle Pivot 1. Lift up and securely block the front of the machine. 2. Measure the clearance (A) between the front axle (3) and front axle support (2).

  • Page 186: Disassembling And Assembling

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM FRONT AXLE [2] DISASSEMBLING AND ASSEMBLING (1) Separating Front Wheel and Wheel Bracket Remove the Front Wheel 1. Inspect all parts for wear or damage. Replace the parts as needed. (When reassembling) • Apply grease to grease fittings. (See page G-8.) 20 to 25 N·m...

  • Page 187: Hydraulic System

    HYDRAULIC SYSTEM KiSC issued 09, 2006 A...
  • Page 188 MECHANISM CONTENTS 1. HYDRAULIC CIRCUIT .................. 4-M1 2. HYDRAULIC PUMP ..................4-M2 3. HYDRAULIC CONTROL VALVE AND VALVE ADAPTOR....... 4-M3 4. LIFT CYLINDER.................... 4-M6 5. MOWER LINKAGE ..................4-M7 KiSC issued 09, 2006 A...

  • Page 189: Hydraulic Circuit

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM HYDRAULIC SYSTEM 1. HYDRAULIC CIRCUIT (1) PTO Clutch (4) Hydraulic Cylinder (7) Oil Cooler (ZD28) (10) Hydraulic Pump (2) PTO Clutch Valve (5) Relief Valve (8) Oil Filter (11) Oil Strainer (3) Hydraulic Control Valve (6) Control Valve...

  • Page 190: Hydraulic Pump

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM HYDRAULIC SYSTEM 2. HYDRAULIC PUMP The oil pump in this engine is a trochoid pump. Inside the pump body, the 6 lobe inner rotor (2) is eccentrically engaged with the 7 lobe outer rotor (1). The inner rotor is driven by the input shaft, which in turn rotate the outer rotor.

  • Page 191: Hydraulic Control Valve And Valve Adaptor

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM HYDRAULIC SYSTEM 3. HYDRAULIC CONTROL VALVE AND VALVE ADAPTOR (1) Return Pipe (3) Control Valve (5) Cylinder Hose A: From Hydraulic Pump (2) Delivery Pipe (4) Control Valve Adaptor (6) Lift Cylinder B: To Transmission Case The hydraulic system consists of the control valve (3), control valve adaptor (4), lift cylinder (6) and etc..
  • Page 192 ZD21N-EC, ZD21-EC, ZD28-EC, WSM HYDRAULIC SYSTEM Neutral (1) Valve Cover (5) Control Valve Adaptor (9) Relief Valve A: To Hydrostatic Transmission (2) Spool (6) Relief Cover (10) P (Pump) Port C: To Lift Cylinder (3) Valve Body (7) Control Lever...
  • Page 193 ZD21N-EC, ZD21-EC, ZD28-EC, WSM HYDRAULIC SYSTEM Overloaded (1) Spool (3) R (Return) Port (5) P (Pump) Port A: To Hydrostatic Transmission (2) Control Valve Adaptor (4) Relief Valve (6) C (Cylinder) Port If the pressure in the circuit exceeds the relief valve setting pressure (3.14 to 3.73 MPa, 32 to 38 kgf/cm , 455 to 540 psi), the relief valve (4) opens to release pressure-fed oil.

  • Page 194: Lift Cylinder

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM HYDRAULIC SYSTEM 4. LIFT CYLINDER (1) Tube End (2) Snap Ring (3) Cylinder Tube (4) Packing (5) Scraper (6) Piston Rod W1014031 The lift cylinder consists of the tube end (1), cylinder tube (3), piston rod (6) and other parts as shown in the figure above.

  • Page 195: Mower Linkage

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM HYDRAULIC SYSTEM 5. MOWER LINKAGE (1) Lift Cylinder (3) Lift Shaft (5) Rear Arm (7) Cutting Height Fine Tuning Bolt (2) Cutting Height Adjusting Dial (4) Front Arm (6) Adjusting Cam (8) Horizon Plate The lift shaft (3) and rear arm (5) are connected directly with clevice pins.
  • Page 196 SERVICING CONTENTS 1. TROUBLESHOOTING ..................4-S1 2. SERVICING SPECIFICATIONS ..............4-S2 3. CHECKING, DISASSEMBLING AND SERVICING........4-S3 [1] HYDRAULIC CONTROL VALVE, PUMP AND CYLINDER ....4-S3 (1) Checking and Adjusting ..............4-S3 (2) Disassembling and Assembling ............4-S3 [2] LIFT CYLINDER..................4-S5 (1) Disassembling and Assembling ............4-S5 KiSC issued 09, 2006 A...

  • Page 197: Troubleshooting

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM HYDRAULIC SYSTEM 1. TROUBLESHOOTING Reference Symptom Probable Cause Solution Page Mower Does Not Rise • Control valve malfunctioning Repair or replace 4-S4 • Lift cylinder damaged Replace 4-S5 • Relief valve spring damaged Replace 4-S4 • Relief valve setting pressure too low...

  • Page 198: Servicing Specifications

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM HYDRAULIC SYSTEM 2. SERVICING SPECIFICATIONS Item Factory Specification Allowable Limit Relief Valve (Control Valve) Setting Pressure 3.14 to 3.73 MPa – 32 to 38 kgf/cm 455 to 540 psi W1013874 KiSC issued 09, 2006 A 4-S2...

  • Page 199: Checking, Disassembling And Servicing

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM HYDRAULIC SYSTEM 3. CHECKING, DISASSEMBLING AND SERVICING [1] HYDRAULIC CONTROL VALVE, PUMP AND CYLINDER (1) Checking and Adjusting Relief Valve Setting Pressure 1. Remove the eye joint bolt (1) from the hydraulic. 2. Install the adaptor, cable and pressure gauge.
  • Page 200 ZD21N-EC, ZD21-EC, ZD28-EC, WSM HYDRAULIC SYSTEM Relief Cover and Relief Valve 1. Unscrew the relief cover mounting screws (6), and remove the relief cover (7). 2. Remove the spool return spring (9). 3. Unscrew the adjusting screw (1), and remove the adjusting shim (2), spring (3), poppet (4) and valve seat (5).

  • Page 201: Lift Cylinder

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM HYDRAULIC SYSTEM [2] LIFT CYLINDER (1) Disassembling and Assembling Removing Lift Cylinder 1. Disconnect the cylinder hose (3) from the lift cylinder (8). 2. Remove the clevis pins (11), (5), and remove the lift cylinder (8).

  • Page 202: Electrical System

    ELECTRICAL SYSTEM KiSC issued 09, 2006 A...
  • Page 203 MECHANISM CONTENTS 1. WIRING DIAGRAM ..................5-M1 2. STARTING SYSTEM ..................5-M5 [1] STARTER ....................5-M7 [2] Glow Plug....................5-M8 [3] SAFETY SWITCH (LIMIT SWITCH) ............. 5-M8 [4] FUEL PUMP.................... 5-M9 [5] ENGINE STOP SOLENOID ..............5-M9 [6] COOLANT TEMPERATURE SWITCH ..........5-M9 3.

  • Page 204: Wiring Diagram

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM 1. WIRING DIAGRAM [ZD21N · ZD21] KiSC issued 09, 2006 A 5-M1...
  • Page 205 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM [ZD28] KiSC issued 09, 2006 A 5-M2...
  • Page 206 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM [ZD21N · ZD21] KiSC issued 09, 2006 A 5-M3...
  • Page 207 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM [ZD28] KiSC issued 09, 2006 A 5-M4...

  • Page 208: Starting System

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM 2. STARTING SYSTEM [ZD21N · ZD21] When the main switch is turned to the PREHEAT position, the terminal 30 is connected to the terminals 19 and AC. The glow plugs become red-hot, and the preheat indicator lamp also lights on while preheating.
  • Page 209 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM [ZD28] When the main switch is turned to the PREHEAT position, the terminal 30 is connected to the terminals 19 and AC. The glow plugs become red-hot, and the preheat indicator lamp also lights on while preheating.

  • Page 210: Starter

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM [1] STARTER (1) Housing (2) Magnetic Switch (3) Overrunning Clutch (4) Drive Lever (5) Internal Gear (6) Gear Shaft (7) Planetary Gear (8) Armature Shaft (9) Yoke (10) Brush Holder (11) Rear End Holder...

  • Page 211: Glow Plug

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM [2] Glow Plug This plug is a two-material type QGS (Quick Glow System) for quick temperature rise, and has self- controlling function as well as excellent durability. The heater (4) connected in series to the heater (3), which also functions as the resistor, is incorporated in the sheath tube (1) of the super glow plug.

  • Page 212: Fuel Pump

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM [4] FUEL PUMP An electro magnetic fuel pump uses a transistor that causes the pump to start pumping fuel when the main switch is turned to the “ON” position. Therefore, fuel is supplied to the fuel injection pump regardless of engine speed.

  • Page 213: Charging System

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM 3. CHARGING SYSTEM The charging system supplies electric power for various electrical devices and also charges the battery while the engine runs. It consists of a AC dynamo and a regulator. KiSC issued 09, 2006 A...

  • Page 214: Ac Dynamo

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM [1] AC DYNAMO The dynamo is an 8-8 pole rotating magnet type generator. It is simple in construction, consisting of a stator and rotor. The rotor is made up of eight permanent magnet pole pieces assembled on a shaft and rotates on...

  • Page 215: Easy Checker

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM [3] EASY CHECKER To check the conditions of tractor easily before and during operation, easy checker combination of lamps on the easy checker board is provided. Indication Items (1) Oil Pressure Lamp When the engine oil pressure is low, this lamp illuminates.

  • Page 216: Gauges

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM 4. GAUGES The fuel quantity and coolant temperature are indicated by the ammeters. The ammeters indicate each amperage flowing through the fuel level sensor for the fuel quantity detection and through the coolant temperature sensor for the coolant temperature detection.

  • Page 217: Coolant Temperature

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM [2] COOLANT TEMPERATURE Coolant Temperature Sensor The coolant temperature sensor is installed to the cylinder head of engine, and its tip is in touch with the coolant. It contains a thermistor (4) whose electrical resistance decreases as the temperature increases.
  • Page 218 SERVICING CONTENTS 1. TROUBLESHOOTING ..................5-S1 2. SERVICING SPECIFICATIONS ..............5-S3 3. TIGHTENING TORQUES ................5-S4 4. CHECKING, DISASSEMBLING AND SERVICING........5-S5 [1] BATTERY....................5-S5 (1) Checking .....................5-S5 [2] STARTING SYSTEM ................5-S7 (1) Checking .....................5-S7 (2) Disassembling and Assembling ............5-S12 (3) Servicing ...................5-S12 [3] CHARGING SYSTEM ................5-S15 (1) Checking ...................5-S15 (2) Disassembling and Assembling ............5-S15 (3) Servicing ...................5-S16...

  • Page 219: Troubleshooting

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM 1. TROUBLESHOOTING Reference Symptom Probable Cause Solution Page All Electrical • Battery discharged or defective Recharge or replace G-26 Equipments Do Not Operate • Battery positive cable disconnected or Repair or replace 5-S5 improperly connected •...
  • Page 220 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM CHARGING SYSTEM Reference Symptom Probable Cause Solution Page Charging Lamp Does • Fuse blown (15 A) Replace G-37 Not Light When Main • Wiring harness disconnected or improperly Repair or replace – Switch Is Turned ON...

  • Page 221: Servicing Specifications

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM 2. SERVICING SPECIFICATIONS Item Factory Specification Allowable Limit Battery Voltage More than 12 V – Potential Less than 0.1 V – Difference Approx. 0.9 Ω Glow Plug Resistance – Starter Commutator O.D. 30.0 mm 29.0 mm...
  • Page 222 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM 3. TIGHTENING TORQUES Tightening torques of screws, bolts and nuts on the table below are especially specified. (For general use screws, bolts and nuts: See page G-9.) Item N·m kgf·m ft-lbs Starter B terminal nut 5.9 to 11.8...

  • Page 223: Checking, Disassembling And Servicing

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM 4. CHECKING, DISASSEMBLING AND SERVICING CAUTION • To avoid accidental short circuit, be sure to attach the positive cable to the positive terminal before the negative cable is attached to the negative terminal. • Never remove the battery cap while the engine is running.
  • Page 224 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM Battery Specific Gravity 1. Check the specific gravity of the electrolyte in each cell with a hydrometer. 2. When the electrolyte temperature differs from that at which the hydrometer was calibrated, correct the specific gravity reading following the formula mentioned in (Reference).

  • Page 225: Starting System

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM [2] STARTING SYSTEM (1) Checking (A) Safety Switches Method of Inspecting Each Control A defective location can be judge by checking function of each safety switch one by one as shown in the table below.
  • Page 226 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM (B) Main Switch Connector Voltage 1. Remove the rear wheel (RH) and fender under cover. 2. Measure the voltage with a voltmeter across the connector 30 (Red) terminal and chassis. 3. If the voltage differs from the battery voltage (11 to 14 V), the wiring harness is faulty.
  • Page 227 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM (C) Starter Motor Test CAUTION • Secure the starter to prevent it from jumping up and down while testing the motor. 1. Disconnect the battery negative cable from the battery. 2. Disconnect the battery positive cable and the leads from the starter.
  • Page 228 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM Glow Plug Continuity 1. Disconnect the lead from the glow plugs. 2. Measure the resistance with an ohmmeter between the glow plug terminal and the chassis. 3. If 0 ohm is indicated, the screw at the tip of the glow plug and the housing are short-circuited.
  • Page 229 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM (F) Fuel Pump Connector Voltage 1. Disconnect the 2P connector from the fuel pump. 2. Turn the main switch key to the “ON” position, and measure the voltage with a voltmeter between the connector terminals.

  • Page 230: Disassembling And Assembling

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM (2) Disassembling and Assembling (1) Magnetic Switch Mounting (2) Housing (3) Magnetic Switch (4) C Terminal Nut (5) Shaft Assembly (6) Drive Lever (7) Overrunning Clutch (8) Connecting Lead (9) Mounting Screw (10) Armature...
  • Page 231 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM Commutator and Mica 1. Check the contact face of the commutator for wear, and grind the commutator with emery paper if it is slightly worn. 2. Measure the commutator O.D. with an outside micrometer at several points.
  • Page 232 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM Armature Coil 1. Check the continuity across the commutator and armature coil core with an ohmmeter. 2. If it conducts, replace the armature. 3. Check the continuity across the segments of the commutaor with an ohmmeter.

  • Page 233: Charging System

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM [3] CHARGING SYSTEM (1) Checking Battery Charging Current 1. After starting the engine, disconnect the battery positive cord (+), and connect an ammeter and voltmeter. Then switch on all electrical loads (such as head lights) and measure the charging current.

  • Page 234: Servicing

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM Rotor 1. Tap out the shaft (1) from the rotor (3). (When reassembling) • Take care the direction of the collar (4), the flat side should face to the pulley (2) side. (1) Shaft...

  • Page 235: Lighting System

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM [4] LIGHTING SYSTEM (1) Checking Charge Lamp (Charging Circuit) 1. Remove the under panel. 2. Disconnect the 6P connector from the regulator after turning the main switch OFF. 3. Turn the main switch ON and connect a jumper lead from the wiring harness connector terminal (Black) to the chassis.

  • Page 236: Gauges

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ELECTRICAL SYSTEM [5] GAUGES (1) Checking Fuel Level Sensor 1) Sensor Continuity 1. Remove the fuel level sensor from the fuel tank. 2. Measure the resistance with an ohmmeter across the sensor terminal and its body.

  • Page 237: Rotary Mower

    ROTARY MOWER KiSC issued 09, 2006 A...
  • Page 238 MECHANISM CONTENTS 1. POWER TRANSMISSION ................6-M1 2. LIFTING MECHANISM ................. 6-M2 KiSC issued 09, 2006 A...
  • Page 239 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ROTARY MOWER 1. POWER TRANSMISSION (1) PTO Shaft (4) Pinion Shaft (6) Outer Blade (10) Bevel Gear Shaft (2) Universal Joint (5) 16T Bevel Gear (RCK54) (7) Outer Pulley (11) Center Pulley (3) 19T Bevel Gear (RCK54)

  • Page 240: Lifting Mechanism

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ROTARY MOWER 2. LIFTING MECHANISM T15060MO00202 (1) Lift Cylinder (3) Rear Arm (4) Horizon Plate (5) Front Arm (2) Lift Shaft The lifting of mower is performed by the hydraulic system on the machine. For avoiding danger, the mower should be kept lifting when traveling. When the position control lever is moved to “LIFT”...
  • Page 241 SERVICING CONTENTS 1. TROUBLESHOOTING ..................6-S1 2. SERVICING SPECIFICATIONS ..............6-S2 3. TIGHTENING TORQUES ................6-S3 4. CHECKING, DISASSEMBLING AND ASSEMBLING ........6-S4 [1] CHECKING AND ADJUSTING ...............6-S4 [2] DISASSEMBLING AND ASSEMBLING..........6-S7 KiSC issued 09, 2006 A...

  • Page 242: Troubleshooting

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ROTARY MOWER 1. TROUBLESHOOTING Reference Symptom Probable Cause Solution Page Blade Does Not Turn • PTO system malfunctioning Check transmission – • Broken mower belt Replace mower belt G-38 Blade Speed Is Slow • Loosen mower belt...

  • Page 243: Servicing Specifications

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ROTARY MOWER 2. SERVICING SPECIFICATIONS Item Factory Specification Allowable Limit Pinion Shaft (without Mower Belt) Turning Force Less than 117.7 N – 12.0 kgf 26.5 lbs Turning Torque Less than 1.47 N·m – 0.15 kgf·m 1.08 ft-lbs...
  • Page 244 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ROTARY MOWER 3. TIGHTENING TORQUES Tightening torques of screws, bolts and nuts on the table below are especially specified. (For general use screws, bolts and nuts: See page G-9.) Item N·m kgf·m ft-lbs Mower blade screw 98.1 to 117.7...

  • Page 245: Checking, Disassembling And Assembling

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ROTARY MOWER 4. CHECKING, DISASSEMBLING AND ASSEMBLING [1] CHECKING AND ADJUSTING Adjusting Anti-scalp Rollers IMPORTANT • The flattest cut can be achieved by having the anti-scalp rollers adjusted off the ground. Check anti-scalp roller adjustments each time the mower deck cutting height is changed.
  • Page 246 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ROTARY MOWER Adjusting Left and Right Cutting Height 1. Wheel pressure must be correct. 2. Raise up the mower deck to the transport position. (Also the top end). 3. Turn the cutting height set dial (1) to the 3 in. cutting height position.
  • Page 247 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ROTARY MOWER Adjusting Front and Rear Cutting Height 1. Wheel pressure must be correct. 2. Raise up the mower deck to the transport position. (Also the top end). 3. Turn the cutting height set dial (1) to the 3 in. cutting height position.

  • Page 248: Disassembling And Assembling

    ZD21N-EC, ZD21-EC, ZD28-EC, WSM ROTARY MOWER [2] DISASSEMBLING AND ASSEMBLING Universal Joint and Belt Covers 1. Remove the universal joint (1). 2. Remove the left and right belt covers (2), (3). (1) Universal Joint (3) Belt Cover (Right) (2) Belt Cover (Left)
  • Page 249 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ROTARY MOWER Gear Box and Mower Belt 1. Turn over the mower. 2. Remove the mower belt (1) from the tension pulley (5). 3. Unscrew the left and right gear box mounting screws (3), (4) and remove the gear box (2) from the mower deck.
  • Page 250 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ROTARY MOWER Center Pulley Holder 1. Unscrew the center pulley holder screws (5) and reamer screws (10). 2. Remove the upper oil seal (11) and lower oil seal (4). 3. Remove the internal snap ring (3) and ball bearing (2).
  • Page 251 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ROTARY MOWER Outer Pulley and Blade Shaft 1. Unscrew the outer pulley mounting nut (20), and remove the outer pulley (23) and feather key (27). 2. Unscrew the pulley holder mounting screws (18), and separate the left pulley holder (29) from the mower deck.
  • Page 252 ZD21N-EC, ZD21-EC, ZD28-EC, WSM ROTARY MOWER Turning Torque of Pinion Shaft 1. Remove the mower belt, and reassemble the gear box to the mower deck. 2. Wind a string around the pinion shaft and set a spring balance (or push-pull gauge) to the tip of the string, and then slowly pull the spring balance horizontally to measure the turning force.
  • Page 253 EDITOR : KUBOTA FARM & INDUSTRIAL MACHINERY SERVICE, LTD. 64, ISHIZU-KITAMACHI, SAKAI-KU, SAKAI-CITY, OSAKA, 590-0823, JAPAN PHONE : ( 81 ) 72-241-1129 : ( 81 ) 72-245-2484 E-mail : ksos-pub@kubota.co.jp Printed in Japan 2004. 07, S, EI, EI, e Code No.9Y011-15151 KUBOTA Corporation 2002.

This manual is also suitable for:

Zd21-ecZd28-ec

Table of Contents

Save PDF