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AGT Agrotk-H12 Operation & Maintenance Manual
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AGT Agrotk-H12 Operation & Maintenance Manual

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H12 MINI CRAWLER EXCAVATOR
OPERATION & MAINTENANCE MANUAL

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Dave Quarantello
February 1, 2025

What grade of hyd oil is used on the H12? AW32 or AW46?

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Ron Hall
February 5, 2025

What type and amount of hydraulic oil do you use in a AGT H12R MINI EXCAVATOR. Thanks

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Summary of Contents for AGT Agrotk-H12

  • Page 1 H12 MINI CRAWLER EXCAVATOR OPERATION & MAINTENANCE MANUAL...
  • Page 2 Preface Chapter I Usage Features and Performance Parameters of H12 Excavators Section I Usage and features Section II Main performance parameters Chapter II Basic Structures and Work principle of H12 Excavators Section I Overview Section II Work principle Section III Basic structure of mechanical system Section IV Basic structure of hydraulic system Chapter III Service Technologies of H12 Excavators Section I Basic construction knowledge...
  • Page 3 Chapter I Usage Features and Performance Parameters of H12 Excavators Section I Usage and features Excavators are provided with excavating, crushing, ditch cleaning, drilling and bulldozing, with their attachments quick hitched and thus its utilization up greatly. In addition, they are easy to operate and transport and flexible to work at narrow site.
  • Page 4 Quick hitch Narrow bucket Log grapple Mechanical thumb Auger Ripper Rake...
  • Page 5 Section II Main performance parameters...
  • Page 6 Overall dimensions Unit: mm A Wheel track B Overall length of track 1203 C Ground clearance of platform D Ground clearance of platform tail E Chassis width F Crawler width H Crawler height I Transportation length 2775 J Overall height 2219 Work range Unit: mm...
  • Page 7 Chapter II Basic Structures and Work Principle of H12 Excavators Section I Overview on H12 excavators H12 excavator is composed of power train, work equipment, swing mechanism, control mechanism, drive system, traveling mechanism and auxiliary equipment, as shown in fig. 1-1. Mounted on the rotary table are the regular full-swing type hydraulic excavators, main components of drive system, swing mechanism and auxiliary devices, which are referred to as upper rotary.
  • Page 8 Section II Work principle of excavators Diesel engine changes the chemical energy of diesel into mechanical energy that is then altered with hydraulic gear pump to hydraulic energy that is distributed to each actuating element (such as hydraulic cylinder, swing motor and traveling motor).
  • Page 9 Section III Basic structure of H12 excavators mechanical system 1 Power system H12 excavator is equipped with single-cylinder air-cooling diesel/gasoline engine, include KOOP/CHANGCHAI or BRIGGS & STRATTON Engine. The KUBOTA engine is three-cylinder water-cooling engine, which is made by Japan. 2 Drive system H12 excavator's drive system could transfer the output power from engine through the hydraulic system to work equipment, swing mechanism and traveling mechanism.
  • Page 10 5.2 Bucket 5.2.1 Basic requirements The longitudinal profile of bucket meets the law of motion of various materials at inside of bucket, facilitating the material flow and minimizing the loading resistance and thus fulfilling the bucket. Bucket teeth are mounted to increase the linear specific pressure of bucket onto material, with unit cutting resistance relatively low and easing to cut in and break soil.
  • Page 11 Hydraulic system structure of H12 excavators I. Rotary motor...
  • Page 12 II. Main pump Driven gear...
  • Page 13 Traveling motor Disc Valve Motors--- BM series -005 and -006...
  • Page 14 Section IV Schematics of main valve...

  • Page 15: Section V. Electrical System Diagram

    Section V. Electrical system diagram...

  • Page 16: Section Ii Preparation For Work

    Chapter III Service Technologies of H12 Excavators Being of high temperature and pressure, the hydraulic oil temperature of H12 excavator can high to 85℃, the engine silencer temperature can high to 700℃ and pressure can high to 16-18Mpa. Therefore, the operators should be specially trained to obtain the proper certificates and to be familiar with the contents in this manual before the operations.
  • Page 17 When hydraulic oil is less than 25℃, it is needed to preheat the machine before any work; otherwise machine may not respond or react very quickly, leading to severe accident. Therefore it is needed to preheat machine if it is cold: ①.
  • Page 18 2.2 Basic excavation Before excavation, the arm cylinder should have angle with the arm as 90°, bucket with ground to be excavated as 30°. Only in such case, can each cylinder have the max excavating force. It is suitable for relatively hard soil, so as to decrease the excavating resistance.

  • Page 19: Section Iv Operational Precautions

    Section IV Operational Precautions Prohibitions and precautions for hydraulic excavators Avoid the landsliding and the stone falling. Avoid any striking of work equipment. Avoid the bucket from colliding with other vehicle body, Avoid loaded bucket crossing over other vehicle cab or persons.

  • Page 20: Section I Daily Inspection And Maintenance

    Chapter VI Maintenance of H12 Excavators Section I Daily inspection and maintenance Interval (h) Item Quantity Remark Check the engine oil level in sump ★ Check the hydraulic oil level in hydraulic oil tank ★ Check the fuel level in tank ★...
  • Page 21 Section II Periods of overhaul, medium and minor repair Interval (h) Item Quantity Remark 1000 1500 2000 2500 4000 Greasing of slewing ★ bearing Greasing of slewing ★ bearing gears Change the engine oil ● ▲ ★ Change the hydraulic △...
  • Page 22 Technical maintenance A Grease Interval (h) Parts Quantity 1000 2000 Pivot at base of boom Pivot at base of boom 1. Lubrication cylinder ★ of work Pivots of bucket and equipment pins connecting rod Others: ★ 2. Lubrication of slewing bearing ★...
  • Page 23 ● Others Pivot between boom and arm; pivot of arm cylinder plunger; pivot at base of bucket cylinder. Slewing bearing - every 250h Park machine on the flat ground. Lower the bucket onto ground. Idle engine at low speed for 5min. Turn the ignition switch to OFF and then take off the key.
  • Page 24 B. Engine oil Interval (h) Parts Quantity 1000 2000 Engine oil ● ▲ ★ Engine oil filter ● ▲ ★ According to the temperature range during the interval, select the viscosity of oil listed in the table below: Recommended engine oil brand: 15W—40 engine oil...
  • Page 25 Inspection of engine oil level ―――each day Change of engine oil ―――every 500 h Change the engine oil filter ―――every 500 h Start up engine to preheat up engine oil properly. Park the vehicle on the flat ground. Lower the bucket onto the ground. Idle engine at low speed for 5min.
  • Page 26 Inspection and maintenance of hydraulic system Caution: in work, the hydraulic system may become very hot. Please cool the machine down before inspection or maintenance! Before maintenance of hydraulic system, make sure the machine stands on flat and solid ground. Lower the bucket onto ground and shut down engine.
  • Page 27 I. Inspection of hydraulic oil level --- each day Important: With no hydraulic oil, never start up engine! Park machine on the flat ground. Completely retract the arm cylinder and extend out the bucket cylinder, so as to locate the machine. Lower the bucket onto the ground.
  • Page 28 III. Change the hydraulic oil ---2000 h Replace the hydraulic oil suction filter element ---- every 1000 h Caution: do not do so until the hydraulic oil cools down as it may be very hot. Park machine on the flat ground. Completely retract the arm cylinder and extend out the bucket cylinder, so as to locate the machine.
  • Page 29 V. Inspection of hose and pipeline --- Each day ---every 250 h Caution: any sprayed fluid could penetrate your skin, leading to personal casualty! Therefore, use a paperboard to check for leakage. In addition, care must be taken to keep your hands and body away from pressure oil. In case of accident, please immediately go to doctor with trauma experience.
  • Page 30 Please use the genuine excavator parts Interval (h) Check points Abnormal Measures Replace it Hose surface Leakage 1 Replace it Hose end Every day Leakage 2 Tighten or replace the Connector body Leakage 3 hose or O-ring Crack 4 Replace it Hose surface Crack 5 Replace it...
  • Page 31 Fuel system capacity of fuel tank: 7L Interval (h) Parts Quantity 1000 2000 Drain dirt out of collector of fuel ★ tank Check the oil-water separator ★ Change the oil-water separator ★ Leakage ★ ★ Check the fuel hose. Crack / twist / others ★...
  • Page 32 Manually loosen the drain plug at bottom of oil- water separator. After the draining, manually tighten the drain to ensure no leakage of oil or air. Caution: after the draining, make sure air is drained out of fuel system to make sure the engine could start up normally.
  • Page 33 Others Interval (h) Parts Quantity 1000 2000 4000 Check if the bucket teeth is worn or ★ loosened. Change the bucket — If needed Replace the bucket and connect the If needed, replace the bucket and connect the new one to —...
  • Page 34 Slide the O-ring out, as shown in the figure. Remove the bucket pins A and B to separate the bucket and the arm. Clean the pin and its pin hole and then properly grease them. Adjust the arm and the new bucket correctly, and make sure the bucket does not roll away.. Install the bucket pins A and B.
  • Page 35 Check the bolts and nuts for tightening torque ……every 250 h (initially at 50 h) Check the tightness at initial 50h and then every 250 h. Tighten it to the set torque if needed. Replace it with bolts and nuts with same or higher grade. Important: please use the torque wrench to check the torques of bolts and nuts! Metric bolts and nuts Thread dimensions...
  • Page 36 Maintenance under the special cases Operational conditions Precautions for maintenance Before operation, check all the drain plugs are tightened up. Moor land, rainy or snowy After operation, clean machine and check bolts and nuts for break, damage, looseness or loss. Lubricate all parts to be lubricated on time. Before operation, check all the drain plugs are tightened up.

  • Page 37: Chapter Xii Troubleshooting

    Chapter XII Troubleshooting Section I General To ensure excellent performance of H12 excavator, high quality Machine's performance and service life are determined not only by manufacturing quality and assembling quality, but also maintenance quality. The marketing representative and service engineer shall remind the user that preventive maintenance is the easiest and most economical one among various ways of maintenance.
  • Page 38 Symptom Possible causes How to solve The main pump supplying fuel to unilateral Change crawler is damaged. The main valve rod is stuck and the spring is Repair or change broken The unilateral crawler fails to move Traveling motor is damaged Change The upper and lower chambers of swivel Change the oil seal or clean the...
  • Page 39 Symptom Possible causes How to solve The sealing component of central rotation Change the sealing component connector is aged and damaged. The left and right crawlers are of different Adjust tightening. Boom (bucket rod and Main valve core is stuck or valve rod spring bucket) move to one Repair or change breaks.
  • Page 40 Symptom Possible causes How to solve other abnormalities) Rotary valve rod on main valve is stuck. Repair Rotary motor is damaged Repair or change The rotation support is damaged. Change The right and left rotation of multi-way Adjust Indifferent left and right valve is of different overloaded pressure rotation speed (no other Rotation valve rod of multi-way valve...
  • Page 41 Section IV Troubleshooting of electrical control system Fault codes of electrical control system of excavator The engine fails to start The engine flames out during operation The engine fails to flame out Automatic slow-down does not work Slewing and traveling of all working devices. Principle diagram 1.
  • Page 42 Possible causes Standard value in regular condition and reference value of fault diagnosis Unlocked 1MΩ Between 105 and Locked Below 1Ω ★Turn the start switch of engine to OFF as preparation and keep it at OFF during diagnosis. If all PS, GND, signals and engine start input are correct while engine start output is abnormal, the engine starter relay fails.
  • Page 43 Section V Troubleshooting of diesel engine Symptoms of failed startup of engine: When starting the engine, the starter drives the engine but the engine fails to be started. Possible causes: (1) Low battery; (2) Battery terminal is rusted or loose; (3) Battery earth wire is rusted or loose or poor GND of engine;...
  • Page 44 (5) Inspect and repair the engine. Only when the engine works well can the start-up fail never or seldom happen. Check if it is hard to start the engine Symptom: (1) Starter runs at correct rpm and drives the engine; however, it is hard to start the engine. (2) It is hard to start the engine when it is cold.
  • Page 45 (4) Start circuit is disabled. (5) Electromagnetic relay armature is adherent; (6) Starter fault (7) Driving gear of starter is stuck by engine flywheel gear ring; (8) Driving gear of starter adheres to the bearing. (9) The starter fails to drive the engine; (10) Engine fault;...

  • Page 46: Attachment: Bom Of Vehicle Parts

    Attachment: BOM of vehicle parts Exploded drawing of 1 . 0 T excavator assembly Name Quantity Remark Upper frame assembly Lower frame assembly Front work equipment assembly Slewing bearing assembly Connecting shaft between boom and upper frame Connecting shaft between boom and upper frame Pivot sleeve...
  • Page 47 1 Lower frame Part No. Part Name Quantity Remark Welded dozer shovel Welded lower frame Slewing joint Rubber crawler Lock nut Sprocket nuts Drive wheel Connecting disc Sprocket bolts 1.10 Bolts fixing the track roller 1.11 Traveling motor 1.12 Track roller 1.13 Idler assembly 1.14...
  • Page 48 2 Upper frame assembly Part No. Part Name Quantity Remark Welded upper frame Covers of rear housing Covers of left housing Covers of right housing Welded inside support frame Rear counterweight plate 1 set Handrail The seat...
  • Page 49 2 Upper frame assembly Part No. Part Name Quantity Remark Left- upper cover 2.10 Right - upper cover 2.11 L- shaped covers 2.12 Console 2.13 Pedal 2.14 Hydraulic oil tank 2.15 The front of the bracket A 2.16 The front of the bracket B 2.17 The seat plate 2.18...
  • Page 50 3. Front work equipment Part No. Part Name Quantity Remark Boom Bucket Connecting rod Push rod Boom cylinder Arm cylinder Bucket cylinder Medium shaft of boom 3.10 Rear shaft of arm cylinder 3.11 Front shaft of arm cylinder 3.12 Front shaft of boom 3.13 Rear shaft of bucket cylinder 3.14...
  • Page 51 VERSION.2022...