D6T Track-Type Tractor Systems Piston Pump (Implement) - Test and Adjust Caterpillar


Piston Pump (Implement) - Test and Adjust
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1.1. Specifications
2.1. Introduction
3.1. Required Tools
4.1. Test Preparation - Low-Pressure Standby
5.1. Test Procedure - Low-Pressure Standby
6.1. Test Preparation - Load Sensing Signal, Pump Discharge Pressure, and Margin Pressure
7.1. Test Procedure - Load Sensing Signal, Pump Discharge Pressure, and Margin Pressure
8.1. Test Preparation - High-Pressure Cutoff
9.1. Test Procedure - High-Pressure Cutoff
10.1. Adjustment Procedure - High-Pressure Cutoff
11.1. Adjustment Procedure - Margin Pressure

------ WARNING! ------

Hot hydraulic oil under high pressure can remain in the components of the hydraulic system or the power train system after the engine has been stopped. The uncontrolled release of the hydraulic oil can cause sudden machine movement and can also result in the following conditions:

  • Burns

  • The penetration of body tissue

  • Other personal injury

  • Death

If hydraulic oil penetrates body tissue, the injury must be treated immediately by a doctor who is familiar with this type of injury. Use a board or a piece of cardboard to check for a hydraulic oil leak. Make sure that all of the attachments have been lowered to the ground and that all trapped pressure has been released from the hydraulic system and the power train system. Also, make sure that the hydraulic oil is cool before the removal of any components or lines. Remove the hydraulic oil filler cap only when the engine is stopped and the filler cap is cool enough to touch with your bare hand.


------ WARNING! ------

Personal injury or death can result from not engaging the parking brake.

Transmission engagement alone will not prevent machine from rolling when the engine is stopped.



NOTICE

Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids.

Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat® products.

Dispose of all fluids according to local regulations and mandates.


Specifications

Table 1
D6T Implement Pump Pressure 
Date  Equipment ID Code 
Pump Pressure  Standard(1)  VPAT Blade(2)  Actual 
Low-Pressure Standby (High Idle) at pressure port (HA)  3600 kPa (520 psi)
Maximum 
3600 kPa (520 psi)
Maximum 
 
High-Pressure Cutoff (High Idle) at pressure port (HA)  19300 ± 350 kPa (2800 ± 50 psi)  21550 ± 350 kPa (3125 ± 50 psi)   
Margin Pressure at High Idle  2100 ± 100 kPa (305 ± 15 psi)  2100 ± 100 kPa (305 ± 15 psi)   
(1) Machines that are equipped with bulldozer lift and bulldozer tilt or machines that are equipped with bulldozer lift, bulldozer tilt, and a ripper
(2) Machines that are equipped with a VPAT blade


Illustration 1g02448491

Table 2
D6T Torque Specifications 
Callout  Torque 
Locknut (2)
High-Pressure cutoff 
21 N·m (15 lb ft) 
Locknut (4)
Margin Pressure 
21 N·m (15 lb ft) 

Introduction

This story includes the following tests:

  • Low-Pressure Standby

  • Load Sensing Signal Pressure

  • Pump Discharge Pressure

  • Margin Pressure

  • High-Pressure Cutoff

This story includes the following adjustment procedures:

  • Adjustment Procedure - High-Pressure Cutoff

  • Adjustment Procedure - Margin Pressure

Required Tools

Note: You can view the discharge pressure of the implement pump through Advisor.



Illustration 2g02571852
Tooling (A)


Illustration 3g01879273
Tooling (D)

Table 3
Tool  Item  Part Number  Description  Qty 
198-4240  Digital Pressure Indicator Gp   
  A1  198-4234  Digital Pressure Indicator 
A2 198-4237  Pressure Sensor (0 to 500 psi) 
A2 198-4239  Pressure Sensor (0 to 6000 psi) 
A3 198-4236  Adapter Cable As 
1U-5796  Pressure Differential Tool Gp   
  D1  177-7861  Hose As 
D2 6V-4143  Quick Connect Coupler 
D3 6V-3965  Fitting 
D4 6V-4144  Quick Connect Coupler 
D5 8T-0859  Pressure Gauge
(0 to 25,000 kPa (0 to 3,600 psi)) 
D5 8T-0861  Pressure Gauge
(0 to 60,000 kPa (0 to 8,700 psi)) 
D6 8C-8431  Tee 
D7 1U-5793  Oil Filter Pressure Differential Gauge Gp 
D8 6V-0484  O-Ring Adapter 

Reference: Refer to Tool Operating Manual, NEHS0818, "Using the 198-4240 Digital Pressure Indicator Group" for more information on using Tooling (A).

Reference: Refer to Special Instruction, SEHS8979, "Component Identification and Calibration of the 1U5796 Differential Pressure Gauge Group" for more information on using Tooling (D).

Test Preparation - Low-Pressure Standby

  1. Move the machine to a smooth horizontal location.

  2. Lower all the implements.

  3. Shut off the engine.

  4. Turn the key to the ON position. Make sure that the implement lockout switch is turned to the UNLOCKED position. Move the implement control levers to all positions several times to release any pressure in the hydraulic system.


    Illustration 4g03665626

  5. Pressure port (HA) is located behind the access door on the right fender of the operators station.

  6. Attach tooling (A) to pressure port (HA). Pressure port (HA) measures the pump discharge pressure.

Test Procedure - Low-Pressure Standby

  1. Perform the steps in the "Test Preparation - Low-Pressure Standby" and then continue to the following steps.

  2. Start the engine. Warm the hydraulic oil to a minimum temperature of 65° C (150° F).

  3. Operate the engine at HIGH IDLE. Make sure that the steering control lever is in the NEUTRAL position.

  4. Make sure that the implement control lever is in the HOLD position.

  5. Record low-pressure standby at pressure port (HA). Low-pressure standby should be a maximum of 3600 kPa (520 psi).

    Note: Low-pressure standby occurs when the engine is running and the implement control levers are in HOLD position. Low-pressure standby is not adjustable. If low-pressure standby is not within the specified limit, perform the test procedure for margin pressure. If necessary, then perform the adjustment procedure for margin pressure.

Test Preparation - Load Sensing Signal, Pump Discharge Pressure, and Margin Pressure

  1. Move the machine to a smooth horizontal location.

  2. Lower all the implements.

  3. Shut off the engine.

  4. Turn the key to the ON position. Make sure that the implement lockout switch is turned to the UNLOCKED position. Move the implement control levers to all positions several times to release any pressure in the hydraulic system.


    Illustration 5g03665626
    (HA) Implement pump pressure


    Illustration 6g03665629
    (HB) Load sensing signal pressure

  5. Pressure port (HA) is located behind the access door on the right fender of the operators station. Pressure port (HB) is on implement pump controller under the cab floor pan.

  6. Attach one set of tooling (A) to pressure port (HA) and one set of tooling (A) to pressure port (HB). Pressure port (HA) measures the pump discharge pressure. Pressure port (HB) measures the pressure of the load sensing signal.

    Note: The load sensing signal is the highest signal that is produced by any of the implement control valves. This signal represents the single greatest load that is being placed on the hydraulic system. The load sensing signal adjusts the pump output to a value that is equal to the load sensing signal pressure plus the margin pressure. Margin pressure is equal to the spring force of the margin spring in the flow compensator valve.

    Note: The pump discharge pressure should be equal to the pressure of the load sensing signal plus margin pressure. Margin pressure should be equal to the spring force of the margin spring that is in the flow compensator valve that is on the implement pump. Refer to Table 1 for the correct margin pressure for your machine.

Test Procedure - Load Sensing Signal, Pump Discharge Pressure, and Margin Pressure

  1. Perform the steps in the "Test Preparation - Load Sensing Signal, Pump Discharge Pressure, and Margin Pressure" and then continue to the following steps.

  2. Start the engine. Warm the hydraulic oil to a minimum temperature of 65° C (150° F).

  3. Operate the engine at HIGH IDLE. Make sure that the steering control lever is in the NEUTRAL position.

  4. Raise the blade.

    Note: The bulldozer control lever should be moved to about 25% of the total travel distance.

  5. Record the pressure at pressure ports (HA) and (HB) as the blade is being raised.

    Note: The margin pressure is the difference between pump discharge pressure (HA) and the pump signal pressure (HB). Margin pressure should be 2100 ± 100 kPa (305 ± 15 psi).

  6. If the margin pressure is within the specified limit, the test is complete.

  7. If the margin pressure is not within the specified limit, perform the adjustment procedure in "Adjustment Procedure - Margin Pressure".

Test Preparation - High-Pressure Cutoff

  1. Move the machine to a smooth horizontal location.

  2. Lower all the implements.

  3. Shut off the engine.

  4. Turn the key to the ON position. Make sure that the implement lockout switch is turned to the UNLOCKED position. Move the implement control levers to all positions several times to release any pressure in the hydraulic system.


    Illustration 7g03665626


    Illustration 8g03665629

  5. Pressure port (HA) is located behind the access door on the right fender of the operators station. Pressure port (HB) is on implement pump controller under the cab floor pan.

  6. Attach one set of tooling (A) to pressure port (HA) and one set of tooling (A) to pressure port (HB). Pressure port (HA) measures the pump discharge pressure. Pressure port (HB) measures the pressure of the load sensing signal.

    Note: The load sensing signal is the highest signal that is produced by any of the implement control valves. This signal represents the single greatest load that is being placed on the hydraulic system. The load sensing signal adjusts the pump output to a value that is equal to the load sensing signal pressure plus the margin pressure. Margin pressure is equal to the spring force of the margin spring in the flow compensator valve.

    Note: The pump discharge pressure should be equal to the pressure of the load sensing signal plus margin pressure. Margin pressure should be equal to the spring force of the margin spring that is in the flow compensator valve that is on the implement pump. Refer to Table 1 for the correct margin pressure for your machine.

Test Procedure - High-Pressure Cutoff

  1. Perform the steps in the "Test Preparation - High-Pressure Cutoff" and then continue to the following steps.

  2. Start the engine. Warm the hydraulic oil to a minimum temperature of 65° C (150° F).

  3. Operate the engine at HIGH IDLE. Make sure that the steering control lever is in the NEUTRAL position.

    Note: Do not hold the machine in the STALL CONDITION for more than 15 seconds at a time.

  4. With the engine at HIGH IDLE, move the ripper control lever to the maximum LIFT position. After the cylinder is at the end of the stroke, the implement pump is at the STALL CONDITION.

    Note: If the machine is not equipped with a ripper, stall the tilt cylinders.

  5. Record high-pressure cutoff at pressure port (HA). High-pressure cutoff should be 19300 ± 350 kPa (2800 ± 50 psi). Refer to Table 1 for the correct high-pressure cutoff for your specific machine.

  6. If the pressure is within the specified limit, the test is complete. If the pressure is not within the specified limit, perform the adjustment procedure in "Adjustment Procedure - High-Pressure Cutoff".

Adjustment Procedure - High-Pressure Cutoff

  1. Perform the Steps in "Test Procedure - High-Pressure Cutoff" and continue to the following step.

  2. Remove the floorplate in front of the operators seat in the cab.


    Illustration 9g02312053
    (1) Adjustment screw for high-pressure cutoff
    (2) Locknut
    (3) Adjustment screw for margin pressure
    (4) Locknut

  3. Loosen locknut (2) while you hold adjustment screw (1) in place.

  4. Turn adjustment screw (1) clockwise to increase the pressure at pressure port (HA) or turn adjustment screw (1) counterclockwise to decrease the pressure at pressure port (HA).

  5. High-pressure cutoff should be 19300 ± 350 kPa (2800 ± 50 psi). Refer to Table 1 for the correct high-pressure cutoff for your machine.

  6. Restart the engine and retest the pressure.

  7. After the pressure is adjusted within the specified limit, tighten locknut (2) to a torque of 21 N·m (15 lb ft). Make sure that you hold adjustment screw (1) in place.

  8. Check the pressure at pressure port (HA) again. When the pressure is at the specified limit, the adjustment procedure is complete.

    Note: The High-Pressure Cutoff adjustment and the Margin Pressure adjustment influence each other. Whenever you adjust one pressure, always check the other pressure and then make any necessary adjustment.

Adjustment Procedure - Margin Pressure

  1. Perform the Steps in "Test Procedure - Load Sensing Signal, Pump Discharge Pressure, and Margin Pressure" and then continue to the following Step.

  2. Remove the floorplate in front of the operators seat in the cab.


    Illustration 10g02312053
    (1) Adjustment screw for high-pressure cutoff
    (2) Locknut
    (3) Adjustment screw for margin pressure
    (4) Locknut

  3. Loosen locknut (4) while you hold adjustment screw (3) in place.

  4. Turn adjustment screw (3) clockwise to increase the margin pressure or turn adjustment screw (3) counterclockwise to decrease the margin pressure.

  5. Perform the steps in "Test Procedure - Load Sensing Signal, Pump Discharge Pressure, and Margin Pressure" to check the margin pressure.

  6. If the margin pressure is 2100 ± 100 kPa (305 ± 15 psi), tighten locknut (4) to a torque of 21N·m (15 lb ft). Make sure that you hold adjustment screw (3) in place.

  7. Check the margin pressure again. If the margin pressure is within the specified limit, the adjustment procedure is complete.

Note: The High-Pressure Cutoff adjustment and the Margin Pressure adjustment influence each other. Whenever you adjust one pressure, always check the other pressure and then make any necessary adjustment.

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