BOLT- 4664758 - Caterpillar

Probable Causes
Contamination of the power train oil
Insufficient pressure oil to the brakes
Transmission clutches do not disengage properly.
System pressure is not correct.
Failed brake components
Brake control valve
Proportional solenoid valveRecommended Actions
Escaping fluid under pressure, even a pinhole size leak, can penetrate body tissue, causing serious injury, and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury.Always use a board or cardboard when checking for a leak.
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, "Caterpillar Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Caterpillar products.Dispose of all fluids according to local regulations and mandates.
Follow this procedure if the machine does not move or if the machine moves slowly.Initially, ensure that the symptom is active. If the symptom is intermittent then a probable cause is oil contamination.Next, a check of the brake pressure guides the diagnosis of the problem to the brake system or to the transmission.If the brake pressure is correct then the brake system is eliminated as the probable cause of the problem. Thus, sufficient pressure is sent to the brake in order to release the brake. Therefore, clutch engagement in the transmission is the probable cause.If the brake pressure is not correct then the brake system is the probable cause of the problem. Next, a check of the system pressure determines if the system pressure is high enough. The system pressure allows the brake control valve to supply sufficient pressure to the brakes.If the system pressure is correct then check the proportional solenoid valve. This check guides the diagnosis of the problem to the brake control valve or to the brakes.Contamination Of The Power Train Oil
If the symptom is not active or if the symptom is intermittent, oil contamination may be the problem.Change the power train oil. Change the oil filter element and clean the screens. Refer to Operation and Maintenance Manual, SEBU8408, "Hydraulic System Oil - Change".Insufficient Pressure Oil To The Brakes
The brakes are engaged by spring force. The brakes are released by pressure oil which is sent from the brake control valve to the brakes. Therefore, insufficient pressure oil to the brakes is a probable cause of the symptom.ReferenceRefer to Testing and Adjusting, KENR8553, "Brake Pressure - Test".Transmission clutches Do Not Disengage Properly
Check for transmission drag.
Place pressure gauges on all transmission clutches.
Start the engine.
Disengage the parking brake.
Press down the service brake pedal in order to engage the brakes.
Shift through all the transmission gears.
Check that the transmission clutches engage properly for each gear. The transmission clutches 1 through 5 operate at the main relief pressure for the transmission when the clutch is engaged.
Check that the clutches disengage properly for each gear. The clutch that is disengaged should have a pressure below