VALVE GP-GAS CONTROL 2395791 - Caterpillar

Table 1
914G and 914G2 Wheel Loader Cylinder Drift    
Cylinder     Time for Drift     Maximum Drift    
Lift Cylinder     5.0 Minutes    
2.0 mm (0.08 inch)    
Tilt Cylinder     5.0 Minutes    
2.0 mm (0.08 inch)    
Table 2
IT14G and IT14G2 Integrated Toolcarrier Cylinder Drift    
Cylinder     Time for Drift     Maximum Drift    
Lift Cylinder     5.0 Minutes    
2.0 mm (0.08 inch)    
Tilt Cylinder     5.0 Minutes    
5.5 mm (0.22 inch)    Note: The drift distances in 1 and 2 are for new machines.
Perform the machine preparation for testing.ReferenceFor more information about preparing the machine for troubleshooting, refer to the Service Manual module Testing and Adjusting, "Machine Preparation for Troubleshooting" for the machine that is being serviced.
Illustration 1 g01051739
Warm the hydraulic oil to normal operating temperature. Normal operating temperature that is needed in order to run the cycle time test is between 38 °C (100 °F) and 65 °C (150 °F). If ET is being used, the hydraulic oil temperature cannot be monitored on the screen. Refer to 1 for a typical view of the screen.
Place the ride control switch in the OFF position.
Extend the lift cylinder and retract the lift cylinder at least five times.
Lift the bucket to the maximum height and move the control lever to the HOLD position.
Place the hydraulic lock lever in the OFF position.
Allow the lift cylinders to retract for 5 minutes. Measure this distance and record this distance.
Extend the tilt cylinder and retract the tilt cylinder at least five times.
Lift the work tool to the maximum height and move the lift control to the HOLD position.
Activate the tilt circuit until the work tool is level to the ground.
Move the tilt control lever to the HOLD position.
Place the hydraulic lock lever in the OFF position.
Allow the tilt cylinders to retract for 5 minutes. Measure this distance and record this distance.
Lower the work tool to the ground.
Turn the engine start switch to the OFF position.Compare the test results with the drift distances listed in 1 for 914G and 914G2 Wheel Loader or in 1 for IT14G and IT14G2 Integrated Toolcarrier.If the cylinder drift is not correct for both the lift and the tilt functions, one of the following conditions are probably present:
The makeup valves in the lift and the tilt control valve are not working correctly.
The valve spools in the main control valve for tilt and the main control valve for lift are excessively worn.
The piston seals in the cylinders are excessively worn.ReferenceFor more information on troubleshooting the hydraulic system, refer to the Service Manual module Testing and Adjusting, "Hydraulic System Troubleshooting" for the machine that is being serviced.