MAT-WATER 1498761 - Caterpillar

Introduction
This test determines cause for machine not traveling straight at partial travel pedal position. Travel drift is the resulting deviation of the machine from a straight line travel with both right and left travel pedals partially depressed. 1. Check machine for travel drift at partial pedal travel.Reference: Refer to, "Operational Tests, Travel Test On Level Ground" Form SENR6187 for additional information. Expected Result:Travel drift should be within the service limits of 1500 mm (59.1 in) in 20 m (22 yds) under all test conditions. Results:* OK - STOP.* NOT OK - Proceed to Step 2.2. Perform Control Valve Shift Pressure Test. For further information refer to the section, "Control Valve Shift Pressure Test". Results:* REPAIRED, OK - STOP.* OK - Proceed to Step 3.3. Perform Negative Flow Control Test. For further information refer to the section, "Negative Flow Control Test". Results:* REPAIRED, OK - STOP.* OK - Proceed to Step 4.4. Check regulation of the main pumps.a. Place the travel speed selector in LOW (tortoise) position. (Testing travel at high speed could involve the motors shifting which affects straight travel if the motors do not shift at the same time).b. Place machine on a hard, level surface.c. Place travel pilot control pedal (lever) at partial FORWARD travel position.d. Drive the machine up an incline to load the pumps and cause them to partially destroke.If the machine drifts to the right, the front pump is destroking before the rear pump. If the drift is to the left, then the rear pump is destroking before the front pump. Expected Result:Travel drift should be within the service limits of 1500 mm (59.1 in) in 20 m (22 yds) on level ground and on an incline. Results:* OK - Proceed to Step 5.* NOT OK - Adjust the pump regulators. STOP.5. Check the travel motor counterbalance valve for sticking.a. Remove the check valve and its spring from the motor return side of the counterbalance valve.b. Move the travel pilot control pedal (lever) to the FORWARD travel position. If machine travels straight, the counterbalance valve is sticking and not opening. Results:* VALVE OK - Proceed to Step 6.* VALVE NOT OK - Replace travel motor counterbalance valve. STOP.6. Perform Swivel Leakage Test. For further information refer to the section, "Swivel Leakage Test". Results:* REPAIRED, OK - STOP.* OK - Proceed to Step 7.7. Perform Travel Motor Case Drain Test. For further information refer to the section, "Travel Motor Case Drain Test". Results:* OK - Cause for problem not found with this test. The test equipment may be faulty, a repair may have been made incorrectly, or an error may have been made during the diagnosis of this problem. Check to determine whether or not the problem is still present. If it is, repeat test procedure. STOP.* REPAIRED, OK - STOP.