CABLE AS 3646980 - Caterpillar

The pilot and braking pump is a fixed displacement gear pump. Measuring the oil flow can provide an indication of the condition of the pump. An inadequate amount of oil flow from the gear pump indicates that there is excessive internal leakage in the pump. This leakage can be caused by wear or damage of the pump components.
Sudden movement or accidental starting of the machine can cause personal injury or death to persons on or near the machine.To prevent personal injury or death, perform the following:Park the machine on a smooth, level surface.Lower the work tool to the ground and engage the parking brake.Stop the engine and remove the key.Block the wheels and install the steering frame lock.
Personal injury can result from hydraulic oil pressure and hot oil.Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system.Make sure all of the work tools have been lowered to the ground, and the oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand.
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids.Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat products.Dispose of all fluids according to local regulations and mandates.
Machine Preparation for Testing
ReferenceFor more information about preparing to test the pilot pump, refer to the Service Manual module Testing and Adjusting, "Machine Preparation for Troubleshooting" for the machine that is being serviced.On the 844H Wheel Dozer and the 990H Wheel Loader, the implement hydraulic system and the brake hydraulic system share the same hydraulic tank. Before fittings, hoses, or components are loosened, tightened, removed, or adjusted, the pressure must be purged from both systems.
Start the engine. Move the transmission direction control switch to the NEUTRAL position.
Engage the parking brake.
Move the steering frame lock to the locked position.
Stop the engine.
Exercise the brakes repeatedly in order to purge the pressure in the hydraulic brake system.
When the engine has stopped, move the hydraulic control levers to all positions in order to purge the pressure in the hydraulic implement system. Place the lift control lever in the FLOAT position. Place the tilt control lever in the HOLD position.
Slowly remove the filler cap on the hydraulic oil tank in order to purge the pressure.
Release all hydraulic pressure before any fitting, any hose, or any component is loosened, tightened, removed, or adjusted.ReferenceFor more information about releasing system hydraulic pressure, refer to the Service Manual module Testing and Adjusting, "System Pressure - Release".
Illustration 1 g01212034
Location of the outlet hose for the pilot/brake pump (1) Pilot/brake pump (A)