966K Wheel Loader Electrohydraulic System Relief Valve (Load Sensing Signal) - Test and Adjust Caterpillar


Relief Valve (Load Sensing Signal) - Test and Adjust
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966K Wheel Loader Electrohydraulic System [UENR1648]
HYDRAULIC SYSTEM
VALVE GP-CONTROL
966K Wheel Loader Electrohydraulic System Pilot Pressure to the Main Control Valve - Check
966K Wheel Loader Electrohydraulic System Relief Valve (Load Sensing Signal) - Test and Adjust
1.1. Specifications
2.1. Introduction
3.1. Required Tools
4.1. Test Preparation
5.1. Test Procedure
6.1. Adjustment Procedure

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

Personal injury or death can result from escaping fluid under pressure.

Escaping fluid under pressure, even a very small pin-hole size leak, can penetrate body tissue and cause serious injury and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury.

Always use a board or cardboard when checking for a leak.



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.



NOTICE

When the compensator is rebuilt, make sure that the pressure compensator adjustment is backed out to a low pressure setting before the engine is started. Otherwise, severe pump and system damage can result.


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

Personal injury can result from hydraulic oil pressure and hot oil.

Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system.

Make sure all of the work tools have been lowered to the ground, and the oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand.


Specifications

Table 1
966K XE Implement Pump Pressure 
Date  Equipment ID Code 
Pump Pressure  Setting  Actual 
Implement Pump Discharge Pressure  31000 ± 700 kPa (4496 ± 100 psi)   

Table 2
966K XE Torque Specifications 
Callout  Torque 
Locknut (3)  17 ± 3 N·m (150 ± 27 lb in) 

Introduction

This information includes the following test:

  • Implement Pump Discharge Pressure

This information includes the following adjustment procedure:

  • Load Sense Adjustment Procedure

Required Tools



Illustration 1g03630357
Tooling (A) 198-4240 Digital Pressure Indicator Gp

Table 3
Tool  Item  Qty  Part No  Description 
  198-4240  Digital Pressure Indicator Gp 
  A1  198-4234  Digital Indicator 
A2 198-4237  Pressure Sensor Gp
(0 to 3,445 kPa (0 to 500 psi)) 
A2 198-4238(1)  Pressure Sensor Gp
(0 to 34,450 kPa (0 to 5,000 psi)) 
A2 198-4239  Pressure Sensor Gp
(0 to 41,368 kPa (0 to 6,000 psi)) 
A2 251-9600(2)  Pressure Sensor Gp
(0 to 68,900 kPa (0 to 10,000 psi)) 
A3 198-4236  Adapter Cable As 
(1) This sensor must be purchased separately. The sensor is not included in the 198-4240 Digital Pressure Indicator Gp
(2) This sensor can only be used on large diameter pressure taps like 6V-3965 Fitting.

Test Preparation

Refer to Testing and Adjusting, "Machine Preparation for Troubleshooting".

Refer to Testing and Adjusting, "System Pressure Release".



    Illustration 2g03630356
    Steering Frame Lock in the LOCKED Position

  1. Move steering frame lock to the LOCKED position.

  2. Prepare the machine for testing by completing the procedure that is specified in the Service Manual module Testing and Adjusting, "Machine Preparation for Troubleshooting" for the machine that is being serviced.

Test Procedure



    Illustration 3g03717364
    Location of implement pump discharge pressure tap. Right side of machine in the articulated hitch.
    (1) Implement pump discharge pressure tap.

  1. Attach a pressure gauge that can sustain pressures up to 34450 kPa (5000 psi) to the implement pump discharge pressure tap (1). The implement pump discharge pressure tap (1) is located on the right side of machine in the articulated hitch as shown in Illustration 3.

    Note: The pressure will need to be released out of the system to attach the pressure gauge.

  2. Start the machine.

  3. Turn off the Ride Control for the machine.

  4. Increase the engine speed to high idle.

  5. Raise the linkage until the machine stalls out in the raised position.

  6. Observe the pressure reading. The implement pump discharge pressure should be 31000 ± 700 kPa (4496 ± 100 psi). If the discharge pressure is not correct, proceed to the following section for instructions to adjust the pressure.

  7. If the discharge pressure is correct, turn off the machine, release the pressure to the hydraulics to disconnect the pressure gauge.

Adjustment Procedure

Adjustments are made to the load sense relief valve located on the main implement valve. The main implement valve is located in the front loader frame. The best way to access the valve is from the right side of the machine in the hitch.



Illustration 4g03718356
(2) Implement load sense relief valve.
(3) Locknut.

  1. Turn off machine.

  2. Locate the implement load sense relief valve (2) as shown in Illustration 4.

  3. Loosen locknut (3) and use an internal hex wrench to adjust the pressure. Turn the adjuster screw clockwise in order to increase the pressure setting. Turn the adjuster screw counterclockwise in order to decrease the pressure setting.

  4. Tighten locknut (3).

  5. Start the machine and measure the new pressure setting with the engine at high idle.

  6. Repeat steps 3 through 5, as needed.

  7. Turn off the machine, release the pressure to the hydraulics to disconnect the pressure gauge.

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