Sauer Danfoss 51 Series Service Manual
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Sauer Danfoss 51 Series Service Manual

Bent axis variable motors
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Series 51
Bent Axis
Variable Motors
Service Manual

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  • Page 1 Series 51 Bent Axis Variable Motors Service Manual...
  • Page 2 Bent Axis Variable Displacement Motors Series 51 General Description Series 51 Variable Displacement Motors are bent Motors equipped with controls normally start at maxi- axis design units, incorporating spherical pistons. mum displacement. This provides maximum starting torque (high acceleration). These motors are designed primarily to be combined with other products in closed circuit systems to trans- The controls may utilize externally or internally sup- fer and control hydraulic power.

  • Page 3: Table Of Contents

    Bent Axis Variable Displacement Motors Series 51 Contents Introduction ..............................4 Basic Hydraulic Circuits ...........................4 General Description of the Series 51 Variable Displacement Motors ..............5 Functional Description ............................6 Technical Specifications and Data - Variable Displacement Motors .............. 20 Safety Precautions ............................21 Gauge Installation ............................23 Start-Up Procedure and Maintenance ......................25 Component Inspection and Adjustment ......................27...

  • Page 4: Introduction

    Bent Axis Variable Displacement Motors Series 51 Introduction The purpose of this manual is to provide information Dirt or contamination is the greatest enemy of any necessary for the normal servicing of the Series 51 type of hydraulic equipment. The greatest possible family of variable displacement hydrostatic motors.

  • Page 5: General Description Of The Series 51 Variable Displacement Motors

    Bent Axis Variable Displacement Motors Series 51 General Description of the Series 51 Variable Displacement Motors The Series 51 variable displacement hydraulic mo- Various hydraulic and electrohydraulic controls may tors use spherical pistons and piston rings. The angle be mounted on the motor end cap to control the servo between the cylinder block and the output shaft can piston and the motor displacement.

  • Page 6: Functional Description

    Bent Axis Variable Displacement Motors Series 51 Functional Description Loop Flushing Series 51 motors used in closed circuit applications incorporate an integral loop flushing valve as stan- dard equipment. Installations that require additional fluid to be removed from the main hydraulic circuit because of fluid cooling requirements, or circuits requiring the removal of excessive contamination from the high pressure circuit, can benefit from loop...
  • Page 7 Bent Axis Variable Displacement Motors Series 51 Functional Description (Continued) Displacement Limiters All Series 51 motors incorporate mechanical dis- placement limiters. The minimum displacement of the motor can be limited within the standard range by a set screw in the motor housing. The maximum displacement can be limited with spacers installed on the servo piston.
  • Page 8 Bent Axis Variable Displacement Motors Series 51 Functional Description (Continued) Hydraulic 2-Position Control (Type N2) This is a two (2) position (maximum - minimum displacement) control, consisting of a cover plate mounted on the end cap. An external control valve supplies servo pressure from an external source directly to the servo piston.
  • Page 9 Bent Axis Variable Displacement Motors Series 51 Functional Description (Continued) Electrohydraulic 2-Position Control (Types E1•E2 and F1•F2) A 12 or 24 VDC solenoid valve, mounted on the multi- function block, connects the end of the control valve spool in the end cap with pilot pressure (provided by the shuttle spool in the multi-function block) or with the motor case.
  • Page 10 Bent Axis Variable Displacement Motors Series 51 Functional Description (Continued) Electric 2-Position Control (Type S1) A 12 VDC solenoid valve, mounted on the multi- function block, directly operates the control valve spool in the end cap. The control valve in the end cap is biased by a threshold spring, and controls oil flow to the ends of the servo piston.
  • Page 11 Bent Axis Variable Displacement Motors Series 51 Functional Description (Continued) Hydraulic Proportional Control (Type HZ) The HZ control consists of a cover plate mounted directly on the end cap. A ball type shuttle valve provides internal servo pressure supply to the control valve in the end cap.
  • Page 12 Bent Axis Variable Displacement Motors Series 51 Functional Description (Continued) Hydraulic Proportional Control (Type HS) The HS control consists of a cover plate (with a hydraulic port) mounted on the multi-function block. Servo pressure may be supplied from an external source or internally by the shuttle spool in the multi- function block.
  • Page 13 Bent Axis Variable Displacement Motors Series 51 Functional Description (Continued) Hydraulic Proportional Control with Electric Override (Types H1•H2 and K1•K2) The function of the H1•H2 and K1•K2 controls is similar to the function of the HS control. A 12 or 24 VDC solenoid valve is installed between the external pilot pressure source and the control spool.
  • Page 14 Bent Axis Variable Displacement Motors Series 51 Functional Description (Continued) Two Line Hydraulic Proportional Control (Type HP) This control consists of a valve block with two (2) hydraulic ports mounted on the multi-function block. The valve block incorporates a shuttle spool and a pilot piston with centering springs.
  • Page 15 Bent Axis Variable Displacement Motors Series 51 Functional Description (Continued) Two Line Hydraulic Proportional Control for “Dual-Path” Vehicles (Type HC) The HC control operates in a similar manner to the HP control, however the HC control is optimized for use in “dual-path”...
  • Page 16 Bent Axis Variable Displacement Motors Series 51 Functional Description (Continued) Electrohydraulic Proportional Control (Types EP and EQ) This control consists of a valve block and PCP (Pres- sure Control Pilot) valve mounted on the multi-func- tion block. The valve block incorporates a pilot piston with centering springs.
  • Page 17 Bent Axis Variable Displacement Motors Series 51 Functional Description (Continued) Multi-function Block Components The Multi-function Valve Block includes a shuttle valve which provides internally supplied servo pres- sure, and an optional Pressure Compensator Over- Ride (PCOR) function with optional brake pressure defeat.
  • Page 18 Bent Axis Variable Displacement Motors Series 51 Functional Description (Continued) An optional “brake pressure defeat” spool may be installed in the multi-function block. When used with the PCOR, this spool assures that the PCOR does not cause the motor displacement to increase during deceleration (which could cause pump overspeed).
  • Page 19 Bent Axis Variable Displacement Motors Series 51 Functional Description (Continued) Pressure Compensator Regulator (Type In this regulator, the Pressure Compensator system in the multi-function block assembly controls the motor displacement. At system pressures below the compensator setting, the servo piston is maintained in the minimum motor displacement position.

  • Page 20: Technical Specifications And Data - Variable Displacement Motors

    Bent Axis Variable Displacement Motors Series 51 Technical Specifications and Data - Variable Displacement Motors Design Hydraulic Fluid Piston motor with variable displacement, bent axis Refer to Sauer-Sundstrand publication BLN-9887 or construction. 697581. Type of Mounting Temperature SAE four (4) bolt flange – SAE Flange Configuration. ϑ...

  • Page 21: Safety Precautions

    Bent Axis Variable Displacement Motors Series 51 Safety Precautions Use caution when dealing with hydraulic When Series 51 units are used in vehicular fluid under pressure. Escaping hydraulic hydrostatic drive systems, the loss of hy- fluid under pressure can have sufficient drostatic drive line power in any mode of force to penetrate your skin causing seri- operation may cause a loss of hydrostatic...
  • Page 22 Bent Axis Variable Displacement Motors Series 51 Notes 20 - 2...

  • Page 23: Gauge Installation

    Bent Axis Variable Displacement Motors Series 51 Gauge Installation Various pressure gauge readings can be a great Snubbers are recommended to protect pressure asset in troubleshooting problems with the Series 51 gauges. Frequent gauge calibration is necessary to motor or support system. insure accuracy.
  • Page 24 Bent Axis Variable Displacement Motors Series 51 Gauge Installation (Continued) Fig. 30-4 - Gauge Ports, Motor with HP Control Port X3: servo press., ext. Gauge port M5: servo press., int. View"V" X1 X2 Ports X1, X2: Control pressure 9/16 — 18 UNF-2B "V"...

  • Page 25: Start-Up Procedure And Maintenance

    Bent Axis Variable Displacement Motors Series 51 Start-Up Procedure and Maintenance Start-Up Precautions Fill the reservoir with recommended hydraulic fluid, which should be passed through a 10 micron (nomi- Cleanliness nal, no bypass) filter prior to entering the reservoir. The use of contaminated fluid will cause damage to Ensure that all system components, including fittings, pipes, and hoses, are completely clean.
  • Page 26 Bent Axis Variable Displacement Motors Series 51 Start-Up Procedure and Maintenance (Continued) Maintenance Changing the Fluid and Filter Cleanliness To insure optimum service life on Series 51 products, regular maintenance of the fluid and filter must be The reservoir breather air filter (if equipped) must be performed.

  • Page 27: Component Inspection And Adjustment

    Bent Axis Variable Displacement Motors Series 51 Component Inspection and Adjustment WARNING The following procedures may require the ve- hicle/machine to be disabled (wheels raised off the ground, work function disconnected, etc.) while performing the adjustments to prevent injury to the technician and bystanders. Charge Pressure Relief Valve Adjustment An appropriate combination of pump and motor charge pressure settings should be maintained to insure the...
  • Page 28 Bent Axis Variable Displacement Motors Series 51 Component Adjustment (Continued) Minimum Displacement Limiter Adjustment The minimum displacement is set at the factory, and the adjustment screw is covered with a tamper- resistant cap WARNING Care should be taken in adjusting displace- ment limiters to avoid undesirable speed con- ditions.
  • Page 29 Bent Axis Variable Displacement Motors Series 51 Component Adjustment (Continued) Maximum Displacement Limiter Adjustment The maximum displacement of the Series 51 motors can be limited by limiting the stroke of the setting piston, and the resulting movement of the valve segment.
  • Page 30 Bent Axis Variable Displacement Motors Series 51 Component Adjustment (Continued) Displacement Control Adjustments NOTE: A change in motor displacement can be de- tected by providing a constant flow of fluid to the motor and monitoring the motor output shaft speed while adjusting the control. An increase in displacement will result in a de- crease in shaft speed, while a decrease in displacement will result in an increase in shaft...
  • Page 31 Bent Axis Variable Displacement Motors Series 51 Component Adjustment (Continued) Hydraulic Proportional Control (Types HZ, HS, H1•H2, and K1•K2) The control start pressure for these controls may be adjusted with the adjusting screw on the end cap (opposite the control block). Control start is that pilot pressure at which the motor displacement starts to decrease.
  • Page 32 Bent Axis Variable Displacement Motors Series 51 Component Adjustment (Continued) Two Line Hydraulic Proportional Control (Type HP) The differential control start pressure for this control may be adjusted with the adjusting screw on the end cap (opposite the control block). Control start is that differential pilot pressure at which the motor displace- ment starts to decrease.
  • Page 33 Bent Axis Variable Displacement Motors Series 51 Component Adjustment (Continued) Two Line Hydraulic Proportional Control for “Dual Path” Vehicles (Type HC) The differential control start pressure for this control may be adjusted with the adjusting screw on the control housing. Control start is that differential pilot pressure at which the motor displacement starts to decrease.
  • Page 34 Bent Axis Variable Displacement Motors Series 51 Component Adjustment (Continued) Electrohydraulic Proportional Control (Types EP and EQ) The control start current for the EP and EQ controls may be adjusted with the adjusting screw on the end cap (opposite the control block). Control start is that current supplied to the PCP (Pressure Control Pilot) valve at which the motor displacement starts to de- crease.
  • Page 35 Bent Axis Variable Displacement Motors Series 51 Component Adjustment (Continued) Pressure Compensator Over-Ride (PCOR) and Pressure Compensator Regulator (Type PC) Adjustment The PCOR or PC regulator valve setting may be adjusted with the adjusting screw on the PCOR/PC valve block attached to the multi-function block. The regulator start pressure is that system pressure at which the PCOR or PC regulator starts to increase the motor displacement.
  • Page 36 Bent Axis Variable Displacement Motors Series 51 Component Adjustment (Continued) Allow the pump to return to its neutral position. Repeat the procedure for the other side of the closed circuit if so configured. The PCOR or PC regulator must operate at the same start pressure as noted previously.

  • Page 37: Troubleshooting

    Bent Axis Variable Displacement Motors Series 51 Troubleshooting Fault-Logic Diagrams • Closed Circuit Check Prime Mover Check Oil Level Check System Check Pump Relief Valve Speed in Reservoir Inlet Pressure Pressure Settings Defective Fill to Proper Inspect Inlet Filter Adjust Level and Replace if Adjust or...
  • Page 38 Bent Axis Variable Displacement Motors Series 51 Troubleshooting (Continued) Fault-Logic Diagrams • Closed Circuit (Continued) Check Charge Check Pump Interchange System Replace Pressure Control System Relief Valves and/or Transmission Charge Check (Pump and Decays in One Defective Valves Motor) Direction (Forward Problem Changes or Reverse) Only Direction...
  • Page 39 Bent Axis Variable Displacement Motors Series 51 Notes 30 - 17...
  • Page 40 Bent Axis Variable Displacement Motors Series 51 Notes 30 - 18...

  • Page 41: Exploded View Of The Series 51 Variable Motor

    Bent Axis Variable Displacement Motors Series 51 Exploded View of the Series 51 Variable Motor The following information is for general parts identi- fication ONLY. Refer to the applicable Service Parts List when ordering service parts. Base Unit OPTION WNNT B71A B70A B70A...
  • Page 42 Bent Axis Variable Displacement Motors Series 51 Exploded View of the Series 51 Variable Motor (Continued) End Cap (..) = Applies to the indicated frame size(s). G30A F10N, F10A–G M18/M98 F20A–G M16/M96 (250) K90N G20A K90A (060—160) G50A G30A K18N G12A (250) (250)
  • Page 43 Bent Axis Variable Displacement Motors Series 51 Exploded View of the Series 51 Variable Motor (Continued) Multi-Function Valve N28A N84A N34A N46/T5 N52/T4 N72A N66A N34A N34A N52/T6 N34A N84A N34A N1A1-A6 N28A N90A N66A N26A N34A Z10 & Z20 N22 &...
  • Page 44 Bent Axis Variable Displacement Motors Series 51 Exploded View of the Series 51 Variable Motor (Continued) Controls M32A M1HS M1HP M1EP•EQ EP•EQ M1S1 M1E1•E2•E5 M22A M1F1•F2 M1H1•H2 M18A M1K1•K2 M2E5 E1•E2•E5 / F1•F2 / H1•H2 / K1•K2 40 - 4...
  • Page 45 Bent Axis Variable Displacement Motors Series 51 Exploded View of the Series 51 Variable Motor (Continued) Controls (Continued) (..) = Applies to the indicated frame size(s). S11T (060, 080, 110) S11T (160, 250) (060, 080, 110) (160, 250) S10T S10T (060, 080, (160, 250) 110)
  • Page 46 Bent Axis Variable Displacement Motors Series 51 Exploded View of the Series 51 Variable Motor (Continued) PC Regulator M84A M28A M34A M72A M66A M34A M34A M34A M84A M34A M28A M90A M28A M26A M34A Z10 & Z20 M22 & M20 M1PC & M21 M27A M27A M23A...
  • Page 47 Bent Axis Variable Displacement Motors Series 51 Exploded View of the Series 51 Variable Motor (Continued) Item Description Quantity Item Description Quantity B000 COMMON PARTS GROUP (SAE FLNG) J00A-K CONTROL START SETTING O-RING J10A-K SPRING-HEL COMP- CONT START FLANGE- SAE SEAT-SPRING SEAL- SHAFT SEAT-SPRING...
  • Page 48 Bent Axis Variable Displacement Motors Series 51 Exploded View of the Series 51 Variable Motor (Continued) Item Description Quantity Item Description Quantity M0HC CONTROL- HYD PRPNL 2LN, DUAL PATH M0HS CONTROL- HYD PRP, 1 LN BUSHING- VALVE ASSY BUSHING-VALVE ASSY M1HC HOUSING- HYD PRPNL (2LN),DUAL M1HS...
  • Page 49 Bent Axis Variable Displacement Motors Series 51 Exploded View of the Series 51 Variable Motor (Continued) Item Description Quantity Item Description Quantity M0PC REGULATOR- PRESS COMP N0A1-6 SVO PRS SPLY, PCOR, DFT PLUG- VALVE BUSHING BORE N1A1-6 HOUSING-MULTI FUNCTION BLOCK O-RING HOUSING-VALVE M1PC...
  • Page 50 Bent Axis Variable Displacement Motors Series 51 Exploded View of the Series 51 Variable Motor (Continued) Item Description Quantity Item Description Quantity S00D-G CONTROL RAMP- HP, HS, H1/H2, K1/K2 Y••• MINIMUM DISPLACEMENT GUIDE-SPRING (160-250) SCREW- SET, FLT PT S10D-G CONT RAMP SPRING (060-110) NUT- HEX, SEAL LOCK S10D-G CONT RAMP SPRING ASSY (160-250)

  • Page 51: Minor Repair And Replacement - Variable Motor

    Bent Axis Variable Displacement Motors Series 51 Minor Repair and Replacement - Variable Motor Charge Pressure Relief Valve Loop Flushing Valve Shaft Seal Control Orifices Multi-function Block Control Minimum Displacement Limiter 51000052 Variable Displacement Motor (SAE Flange Configuration) Fig. 50-1 - Minor Repairs Minor Repairs may be performed, following the proce- Protect all exposed sealing surfaces and open cavi- dures in this section, without voiding the unit war-...

  • Page 52: Shaft Seal (Sae Flange Configuration)

    Bent Axis Variable Displacement Motors Series 51 Minor Repair and Replacement - Variable Motor (Continued) Shaft Seal (SAE Flange Configuration) Lip type shaft seals are used on the Series 51 motors. Replacement of the shaft seal usually requires re- moval of the motor from the machine. Remove the screws holding the flange to the housing, using a 6 mm internal hex wrench (060 and 080 units), an 8 mm internal hex wrench (110 units), a 10 mm...

  • Page 53: Shaft Seal (Cartridge Configuration)

    Bent Axis Variable Displacement Motors Series 51 Minor Repair and Replacement - Variable Motor (Continued) Install a new O-ring on the flange. Prior to assembly, lubricate the flange O-ring and the I.D. of the seal with petroleum jelly. Protect the seal lip from damage during installation by wrapping the spline or key end of shaft with plastic film, or by using a seal installation tool.

  • Page 54: Loop Flushing Shuttle Valve (Option)

    Bent Axis Variable Displacement Motors Series 51 Minor Repair and Replacement - Variable Motor (Continued) Install the carrier O-ring into the groove in the hous- ing. Prior to assembly, lubricate the carrier O-ring and the I.D. of the seal with petroleum jelly. Protect the seal lip from damage during installation by wrapping the spline or key end of shaft with plastic film, or by using a seal installation tool.

  • Page 55: Charge Pressure Relief Valve

    Bent Axis Variable Displacement Motors Series 51 Minor Repair and Replacement - Variable Motor (Continued) Charge Pressure Relief Valve Before removing the screw adjustable relief valve plug, mark the plug, lock nut, and end cap to allow maintaining the original adjustment when assem- bling.

  • Page 56: Hydraulic 2-Position Control (Type N2)

    Bent Axis Variable Displacement Motors Series 51 Minor Repair and Replacement - Variable Motor (Continued) Hydraulic 2-Position Control (Type N2) Thoroughly clean external surfaces prior to removal of cover plate. Remove the four (4) screws retaining the cover plate to the end cap with an 8 mm internal hex wrench (060, 080, and 110 units) or a 10 mm internal hex wrench (160 and 250 units).

  • Page 57: Electrohydraulic 2-Position Controls (Types E1•E2 And F1•F2)

    Bent Axis Variable Displacement Motors Series 51 Minor Repair and Replacement - Variable Motor (Continued) Electrohydraulic 2-Position Controls (Types E1•E2 and F1•F2) Thoroughly clean external surfaces prior to removing the control. The solenoid may be removed from the valve by removing the nut with a 3/4"...

  • Page 58: Electric 2-Position Controls (Type S1)

    Bent Axis Variable Displacement Motors Series 51 Minor Repair and Replacement - Variable Motor (Continued) Electric 2-Position Controls (Type S1) Thoroughly clean external surfaces prior to removing the control. Remove the screws retaining the solenoid and sole- noid adapter plate to the multi-function block with a 4 mm internal hex wrench.

  • Page 59: Hydraulic Proportional Control (Type Hz)

    Bent Axis Variable Displacement Motors Series 51 Minor Repair and Replacement - Variable Motor (Continued) Hydraulic Proportional Control (Type HZ) Thoroughly clean external surfaces prior to removal of control. Remove the four (4) screws retaining the valve hous- ing to the end cap with an 8 mm internal hex wrench (060, 080, and 110 units) or a 10 mm internal hex wrench (160 and 250 units).

  • Page 60: Hydraulic Proportional Control (Type Hs)

    Bent Axis Variable Displacement Motors Series 51 Minor Repair and Replacement - Variable Motor (Continued) Hydraulic Proportional Control (Type HS) Thoroughly clean external surfaces prior to removal of control. Remove the screws retaining the valve housing to the multi-function block with a 4 mm internal hex wrench. Remove the valve housing.

  • Page 61: Hydraulic Proportional Control With Maximum Angle Over-Ride (Types H1•H2 Or K1•K2)

    Bent Axis Variable Displacement Motors Series 51 Minor Repair and Replacement - Variable Motor (Continued) Hydraulic Proportional Control with Maximum Angle Over-ride (Types H1•H2 or K1•K2) Thoroughly clean external surfaces prior to removing the control. The solenoid may be removed from the valve by removing the nut with a 3/4"...

  • Page 62: Two Connection Hydraulic Proportional Control (Type Hp)

    Bent Axis Variable Displacement Motors Series 51 Minor Repair and Replacement - Variable Motor (Continued) Two Connection Hydraulic Proportional Control (Type HP) Thoroughly clean external surfaces prior to removal of control. Hold the control housing in position, and remove the screws retaining the cover and control housing to the multi-function block with a 4 mm internal hex wrench.
  • Page 63 Bent Axis Variable Displacement Motors Series 51 Minor Repair and Replacement - Variable Motor (Continued) Install the pilot piston pin in the multi-function block. Install the outer (thin) shuttle piston plug with the large chamfer toward the shuttle valve bore. Install the shuttle spool into its bore and install the inner (thick) plug with the large chamfer toward the shuttle valve bore.

  • Page 64: Two Connection Hydraulic Proportional Control For "Dual Path" Vehicles (Type Hc)

    Bent Axis Variable Displacement Motors Series 51 Minor Repair and Replacement - Variable Motor (Continued) Two Connection Hydraulic Proportional Control for “Dual Path” Vehicles (Type HC) Bleed Valve Loosen the seal lock nut on the bleed valve with a 10 mm hex wrench, and remove the valve with a 4 mm internal hex wrench.
  • Page 65 Bent Axis Variable Displacement Motors Series 51 Minor Repair and Replacement - Variable Motor (Continued) Pilot Piston and Control Housing Thoroughly clean external surfaces prior to disas- sembly of control. Remove the four (4) screws retaining the cover to the control housing with a 4 mm internal hex wrench.
  • Page 66 Bent Axis Variable Displacement Motors Series 51 Minor Repair and Replacement - Variable Motor (Continued) The plugs on the control housing may be removed with a 7/16" hex wrench or a 1/4" internal hex wrench. When reinstalling, torque the 5/16" plugs to 9 Nm (7 ft•lbsf), and the 9/16"...
  • Page 67 Bent Axis Variable Displacement Motors Series 51 Minor Repair and Replacement - Variable Motor (Continued) Install the control start spring into the control housing. Install the pilot piston pin. The end of the pin must engage the recess in the end of the control valve spool.

  • Page 68: Electrohydraulic Proportional Control (Types Ep And Eq)

    Bent Axis Variable Displacement Motors Series 51 Minor Repair and Replacement - Variable Motor (Continued) Electrohydraulic Proportional Control (Types EP and EQ) Thoroughly clean external surfaces prior to removal of control. The Pressure Control Pilot (PCP) valve may be removed from the control valve housing, as de- scribed under the following heading.
  • Page 69 Bent Axis Variable Displacement Motors Series 51 Minor Repair and Replacement - Variable Motor (Continued) Install the pilot piston pin in the multi-function block. Position the valve housing (with O-rings) on the multi- function block. 51000097 51000127 Fig. 50-101 - Pilot Fig.

  • Page 70: Pressure Control Pilot (Pcp) Valve For Electrohydraulic Proportional Control (Types Ep And Eq)

    Bent Axis Variable Displacement Motors Series 51 Minor Repair and Replacement - Variable Motor (Continued) Pressure Control Pilot (PCP) Valve for Electrohydraulic Proportional Control (Types EP and EQ) Thoroughly clean external surfaces of control. Using a 4 mm internal hex wrench, remove the four (4) screws and remove the PCP valve.

  • Page 71: Multi-Function Block

    Bent Axis Variable Displacement Motors Series 51 Minor Repair and Replacement - Variable Motor (Continued) Multi-function Block Removal and Installation Remove the external control assembly as described in the instructions for the specific control. Remove the four (4) screws (and washers for 060, 080, and 110 units) retaining the multi-function block to the end cap with an 8 mm internal hex wrench (060, 080, and 110 units) or a 10 mm internal hex wrench...
  • Page 72 Bent Axis Variable Displacement Motors Series 51 Minor Repair and Replacement - Variable Motor (Continued) Servo Pressure Supply Shuttle Spool Remove the servo pressure supply shuttle spool plug from the multi-function valve with a 9/16" hex wrench. NOTE: If a pressure compensator valve block is installed, the opposite end of the shuttle spool bore in the multi-function valve is plugged with an internal hex head plug lo-...
  • Page 73 Bent Axis Variable Displacement Motors Series 51 Minor Repair and Replacement - Variable Motor (Continued) Blocking Plate for Multi-function Block Without PCOR The blocking plate may be removed by removing the four (4) screws with a 5 mm internal hex wrench. Remove the O-rings from the plate.
  • Page 74 Bent Axis Variable Displacement Motors Series 51 Minor Repair and Replacement - Variable Motor (Continued) Install the valve block on the multi-function block and install the screws. Torque the screws to 11 Nm (8 ft•lbsf). Install the valve block plug and torque to 54 Nm (40 ft•lbsf).
  • Page 75 Bent Axis Variable Displacement Motors Series 51 Minor Repair and Replacement - Variable Motor (Continued) PCOR Brake Pressure Defeat Spool Remove the PCOR defeat spool bore plugs or fittings with a hex wrench. Remove the PCOR defeat spool stop plugs with a 7⁄16"...

  • Page 76: Pressure Compensator Regulator (Type Pc)

    Bent Axis Variable Displacement Motors Series 51 Minor Repair and Replacement - Variable Motor (Continued) Pressure Compensator Regulator (Type The PC regulator utilizes the multi-function block and pressure compensator valve to control the motor displacement. Service procedures for these components are in- cluded in the “Multi-function Block”...

  • Page 77: Control Orifices

    Bent Axis Variable Displacement Motors Series 51 Minor Repair and Replacement - Variable Motor (Continued) Control Orifices Orifices are installed in the motor end cap to regulate oil flow to the servo control valve and the servo piston. To gain access to these orifice plugs, remove the three (3) plugs located on the motor end cap nearest the multi-function block or control, using a 7⁄16"...
  • Page 78 Series 51 MV Sheet 1 of 2 Genuine Service Parts Minor Repair Instructions 4-Way Valve and Feedback Springs...
  • Page 79 Series 51 MV Sheet 2 Genuine Service Parts Minor Repair Instructions 4-Way Valve and Feedback Springs - HC Control...
  • Page 80 Hydraulic Power Systems Sauer-Danfoss Hydraulic Power Systems - Market Leaders Worldwide Sauer-danfoss is a world leader in the design Sauer-danfoss specializes in integrating a full and manufacture of Hydraulic Power Systems. Research range of system components to provide vehicle and development resources in both North America and designers with the most advanced total-design system.

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