SEAL 0990479 - Caterpillar

Illustration 13 g01192338
(27) Fixed ball valve
(28) Mobile ball valve
(29) Drain Plug
Remove the cover plates from the fixed ball valve (27) and the mobile ball valve (28).
Connect the mobile ball valve (28) to the fixed ball valve (27).
Install the bolts into the mobile ball valve (28).
Open the fixed ball valve (27) and open the mobile ball valve (28). Use the levers that are located in the tool box in order to open the ball valves.
Place drain plugs (29) into the leakage oil ports.
Connect the quick connectors (26) by using the following instructions.
Hydraulic oil pressure can remain in the hydraulic systems after the engine and pump have been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic systems. To prevent possible injury, refer to the section, Testing and Adjusting, "Hydraulic System Pressure - Release" before any fitting, hose or component is loosened, tightened, removed or adjusted.When possible, the bucket or attachment must always be lowered to the ground before service is started. When it is necessary for the boom to be in the raised position while tests or adjustments are done, be sure that the boom, stick and bucket or attachment have correct support.The swing lock (if equipped) must be engaged before service is started.Always move the machine to a location away from the travel of other machines. Be sure that other personnel are not near the machine when the engine is running and tests or adjustments are being made.
Illustration 14 g01192662
Remove the dust caps from the male coupling of the quick disconnect. Remove the dust caps from the female coupling of the quick disconnect. Carefully clean all mating surfaces of the coupling for the quick disconnect.
Hold the flat face of the female end (32) of the coupling against the male end (30) of the coupler. Hold the female end (32) forward and rotate the main sleeve (33) clockwise.
Continue the manual connection if pressure is not felt. If pressure is detected use an open wrench and turn the coupler clockwise until the connection is completed. The completed connection is determined by the automatic feed of the sleeve (31). This will prevent the incidental loosening of the hose due to vibration.
Connect the male dust caps and the female dust caps together. Note: Always connect the dust cap to another dust cap when the coupling for the quick disconnect is active. This keeps dirt and other foreign material from contaminating the hydraulic system.
Remove the caps and the plugs from the hydraulic fittings.
Install the bolts, clamps, and the hydraulic hoses for the ball valves (25) that are located on the boom foot.
Open the four ball valves (25). Purging the Hydraulic Circuits
After the assembly of the front parts and reconnection of the hydraulic lines, it is necessary to purge all of the hydraulic lines.Special attention should be given to the following hydraulic lines:
Load sensing line from the fore boom valve
Two pilot lines from the fore boom valve
Pilot line from the stick lowering control valveIn order