Tuesday, December 4, 2012

797F Off-Highway Truck ; Relief Valve (Hoist Cylinder Rod End) - Test and Adjust

Table 1
Required Tools
Qty	Part Number	Description
1	131-5051	DataView Tool Gp
2	131-5064	Adapter Cable As
2	213-3276	Pressure Sensor
2	6V-4144	Quick Connect Couplers
2 ⁽¹⁾	2P-8421	O-Ring Adapters
2 ⁽¹⁾	3D-2824	O-Ring Seals
2 ⁽¹⁾	6V-3965	Fitting As
2 ⁽¹⁾	3J-1907	O-Ring Seals

^( 1 )

Required only when using the hoist cylinder buddy dump ports.

Note: Refer to the Hydraulic System Systems Operation/Testing and Adjusting, "Using Caterpillar DataView to Determine Test Data" in order to learn more about connecting Caterpillar DataView (DataView) to the sensors.


Front view of the hoist control valve (1) Relief valve for the main supply pressure(2) Relief valve for the rod end of the hoist cylinder


Hoist cylinder (3) Rod end port(4) Head end port

Lower the dump body to the DOWN position.

Stop the engine.

Install one 2P-8421 O-Ring Adapter and one 3D-2824 O-Ring Seal to rod end port (3). Connect one 6V-3965 Fitting As and one 3J-1907 O-Ring Seal onto the 2P-8421 O-Ring Adapter .Note: Alternate pressure taps can be used. See Illustration 3.


Rear view of the hoist control valve(5) Rod end port

Connect the 6V-4144 Quick Connect Coupler to the 213-3276 Pressure Sensor. Connect this assembly to the rod end tap port that is located on the hoist control valve. Use the 131-5064 Adapter Cable As in order to connect the pressure sensor to one of the analog inputs on the dataview tool group.Note: In place of the datalogger unit a 0 to 40000 kPa (0 to 5800 psi) 198-4240 Digital Pressure Indicator with the proper test hoses may be used.

Set up the datalogger.Note: Be sure to set the timer on the datalogger in order to allow enough time to start the engine and complete the test.

Start the engine.

Operate the dump body repeatedly until the temperature of the hydraulic oil reaches 38 °C (100 °F).

Start the datalogger on dataview tool group.

Lower the dump body below the second stage of the hoist cylinder.

Operate the engine at HIGH IDLE.

Raise the dump body until the hoist cylinders are fully extended.

Repeat Step 9 through Step 11 three times.Note: If the 8T-0860 Pressure Gauge is used, check the pressure on the gauge when the dump body reaches the middle of the second stage of the hoist cylinder. Check the pressure setting while the dump body is being raised. When the hoist cylinder reaches the middle of the second stage, the Chassis Electronic Control Module sends a signal to the hoist control valve. This signal shifts the spool that drains the rod end oil to the hydraulic tank. The oil in the rod end of the hoist cylinders is forced to open relief valve (3) .

Lower the dump body to the DOWN position.

Stop the engine.

Stop the datalogger.

Download the file from the datalogger.

View the graph of the data. Observe the pressure of the relief valve for the rod end of the hoist cylinder when the engine is at high idle.Note: The pressure setting of the relief valve for the rod end of the hoist cylinder during the middle of the second stage to the full RAISE position is 23200 ± 500 kPa (3370 ± 70 psi) at HIGH IDLE.

If the pressure needs to be adjusted, proceed to Step 19. If the pressure does not need to be adjusted, proceed to Step 23.


Hoist cylinder rod end relief valve (6) Locknut(7) Setscrew

Loosen locknut (6) .

With a flat head screwdriver, rotate setscrew (7) clockwise by a quarter turn in order to increase the pressure. Rotate setscrew (7) counterclockwise by a quarter turn in order to decrease the pressure.Note: Each quarter turn of setscrew (7) changes the pressure approximately 1500 kPa (215 psi).