FINAL DRIVE GP 7I7704 - Caterpillar

Contamination to a closed loop hydraulic system can cause serious damage to the hydraulic motor and to the hydraulic pump.In order to prevent damage to the hydraulic motor and to the hydraulic pump, perform the flushing procedure whenever any hydraulic oil line or any hydraulic connections have been opened.
Table 1
Required Tools    
Tool     Part Number     Description     Qty    
A     198-4240     Digital Pressure Indicator     1    Refer to Testing and Adjusting, "Machine Preparation for Troubleshooting" before you start this procedure.
Disconnect the wiring harness from the pump controls in order to keep the piston pump (auger) from inadvertently activating the piston pump (auger) during the flushing procedure.
Illustration 1 g00767940
(1) Return line (2) Motor case drain line (3) Flushing port (4) Pressure line (5) Flushing port (6) Flushing port
Disconnect pressure line (4) from the piston motor (auger). Reconnect pressure line (4) to flushing port (5). Cover the open port with the hardware that was removed from flushing port (5) .
Disconnect motor case drain line (2) from the piston motor (auger). Reconnect motor case drain line (2) to flushing port (3). Use the cap from flushing port (3) in order to cover the open elbow from motor case drain line (2) .
Illustration 2 g01010715
Install tooling (A) .
Flush one line. During the flushing procedure, the pressure from the gear pump (charge) must stay between 350 to 2710 kPa (51 to 394 psi). The pressure must stay above 350 kPa (51 psi) in order to provide adequate flushing and cooling of the piston pump (auger). The pressure must stay below 2710 kPa (394 psi). This will keep the oil flow from the gear pump (charge) from bypassing across the relief valve.
Run the engine at high idle for 10 minutes. Monitor the pressure at the gear pump (charge) and monitor the temperature of the hydraulic system. Do not allow the temperature of the hydraulic system to rise above 93 °C (199 °F).
Shut off the engine. Loosen the hydraulic tank cap in order to relieve hydraulic system pressure. Replace the pressure line and replace the flushing port covers to the original positions.
Illustration 3 g00768008
(7) Flushing port
Disconnect return line (1) from the block of the piston motor (auger). Reconnect return line (1) to flushing port (7). Cover the open port with the hardware that was removed from flushing port (7).
Remove motor case drain line (2) from flushing port (3). Move motor case drain line (2) to the other side to flushing port (6). Use the cap from flushing port (6) in order to cover flushing port (3). Repeat the flushing procedure for this side.
Loosen the hydraulic tank cap in order to relieve hydraulic system pressure.
Restore all of the hydraulic oil lines to the original positions.
Replace the motor case drain filter. Replace the charge pump filter and replace the case drain filter for the pump.