BUSHING 2244978 - Caterpillar

Transmission Drive Problem: Is It A Retraction Circuit Leak?
The first step in troubleshooting a transmission drive problem is to check the transmission pump outlet pressure. See the correct Service Manual for the procedure to test the pump outlet pressure.
If the pressure is in the range shown in the specification chart, there is no indication of internal leakage in the brake retraction circuit. The troubleshooting procedure in the Service Manual must be followed to find and correct the problem in the transmission system.
The retraction circuit must be checked as a possible source of leakage if the pump outlet pressure is below the specifications. DO NOT remove the gauge from pressure tap after the transmission pump outlet pressure test. This pressure will be checked again.
Troubleshooting Procedure
First, check the complete brake retraction circuit (including both brakes) for an internal oil leak. To do this, install a gate valve or needle valve and a 600 psi (4150 kPa) gauge between the brake control valve group, fastened to the transmission, (9J3375 Brake Valve Group on 776 Tractors and 777 Trucks, and 9J4608 Valve Group on 772B and 768C Tractors, and 773B and 769C Trucks) and brakes. (See Illustration 1, Location 1).
Illustration 1. Locations of needle valve or gate valve and gauge for leakage test of the emergency--parking brake retraction circuit. Use location 1 to test complete retraction circuit, location 2 to test the right brake and lines, and location 3 to test the left brake and lines. The gauge MUST always be between the needle valve or gate valve and the brakes. The gauge MUST be installed between the needle valve or gate valve and the brakes.Make sure the needle valve or gate valve does not leak when it is closed.
With the engine at high idle, and the parking brake control lever in the "Off" position, the pressure must be in the specifications shown in the chart. Some times, leakage will not permit the system to be charged to the pressure shown in the specifications.
Close the needle valve or gate valve and look at the gauge. If the pressure has not decreased 100 psi (690 kPa) after one (1) minute, there is not enough leakage to have an effect on the brake retraction circuit. With the valve still closed, check to see if the transmission oil pump outlet pressure increases to the specifications. If this pressure does not increase to the specifications, use the Service Manual for troubleshooting the transmission system, starting with the transmission oil pump.
If the pressure in the retraction circuit decreases 100 psi (690 kPa) or more in the first minute, there is leakage and each component must be checked.
Each wheel brake is checked by the installation of the gate valve or needle valve and the gauge in the lines to each brake. (See Illustration 1, locations 2 and 3). The gauge MUST be installed between the needle valve or gate valve, and the brake. Again, with the engine at high idle and the parking brake control lever in the