793D Off-Highway Truck Power Train: Torque Converter and Transmission Hydraulic System Troubleshooting PART2

Check: Check inside the transmission case

(10) Transmission drain plugs

Remove plugs (10) in the bottom of the transmission case. This will drain all the oil out of the transmission and the transfer gears. Measure the total amount of the oil that is removed at both plugs. Inspect the oil for foreign material.

Problem: More than 76 L (20 US gal) of oil is drained.

Transmission and torque converter gear pump (3) Transmission lubrication section (4) Transmission charging pump section (5) Torque converter charging pump section(6) Transmission scavenge pump section

Lower right side of the transmission case(8) Transmission magnetic screens inside the case

Probable Cause

• Failure of the transmission scavenge pump section (6)
• Restriction in transmission magnetic screens (8)
• Too much leakage in a transmission clutch

Problem: Iron chips or steel chips are found.

Probable Cause

• Broken components in the transfer gears or in the transmission

Problem: Aluminum particles are found.

Probable Cause

Worn housings, worn load pistons, or worn selector pistons in the pressure control valve

Check: Check inside the torque converter sump

Torque converter sump(11) Cover for the suction screen

Drain the oil from the torque converter sump. Remove cover (11). Remove the suction screen. Clean the suction screen.

Problem: Rubber particles are found.

Probable Cause

• Seal failure
• Hose failure

Problem: Shiny steel particles are found.

Transmission and torque converter gear pump (3) Transmission lubrication section (4) Transmission charging pump section (5) Torque converter charging pump section(6) Transmission scavenge pump section

(12) Pump drive

Problem: Shiny steel particles are found.

Probable Cause

• A worn drive gear or a worn driven gear on torque converter charging pump section (5)
• Mechanical failure of the transmission scavenge pump section (6)
• There is a mechanical failure of pump drive (12). Drain the pump drive. Inspect the oil pump drive.
• There is a worn flywheel or a worn starter motor pinion gear on the engine. Inspect the starter motor pinion gear and the flywheel gear.

Overheated Transmission Hydraulic System

An overheating condition in the hydraulic system will probably be first detected through Vital Information Management Systems (VIMS). The temperature sensor for the torque converter is located near the torque converter screen. The temperature sensor for the transmission lubrication oil is located at the entrance of the oil into the transfer gears. Both the sensors provide input signals to the VIMS.

Probable Cause

Right side of the engine(1) Oil cooler for the torque converter and the transmission

• Restriction in oil cooler (1) for the torque converter and the transmission

Transmission and torque converter gear pump (3) Transmission lubrication section (4) Transmission charging pump section (5) Torque converter charging pump section(6) Transmission scavenge pump section

• Failure in any section of the oil pump for the transmission and the torque converter. Perform the checks in "Check the torque converter hydraulic filter" and in "Check the transmission charging hydraulic filter".
• There may be a restriction in one of the hose assemblies.
• The machine is operating too long in torque converter drive with an extreme load.

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793D Off-Highway Truck Power Train: Torque Converter and Transmission Hydraulic System Troubleshooting PART2 2013-01-06T20:25:00-08:00 Rating: 4.5 Diposkan Oleh: Unknown