COUPLING 2D0296 - Caterpillar

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, "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.
This section provides probable causes to known problems. Since there may be several probable causes, specific inspections or instrument tests may be recommended. These inspections and tests will help to identify the causes that are most probable.Note: Use oil with the correct viscosity for the operating conditions.Problem List
Problem List for the Service Brakes
The accumulator pressure will not reach cutout pressure at low idle. This typically causes a Warning Category 3 to occur. This may also engage the parking brake.
The front service brakes do not operate, and the warning system is not activated.
The rear service brakes do not operate, and the warning system is not activated.
Service brakes slip, and the warning system is not activated.
The service brakes are not applied evenly.
Too much force needed to push the brake pedals, and the warning system is not activated.
Problem List for the Parking Brake
The parking brake does not hold the machine stationary.
The parking brake does not engage when the parking brake control knob is pulled out.
Problem List for the Charging System for the Service Brakes
The low oil pressure warning will not turn off.
Problems with the Service BrakesProblem 1The accumulator pressure does not reach the cutout pressure at low idle. This typically causes a Warning Category 3 to occur. This problem may also engage the parking brake.Probable cause
When the hydraulic oil is hot and the engine is running at low idle, the output of the pump is not sufficient to overcome the pump's own internal losses. Problem 2The front service brakes do not operate, and the warning system is not activated.Probable causes
The brake group within the axle housing is damaged.
The lines to the front service brakes are obstructed.
The front circuit of the service brake control valve is faulty. Problem 3The rear service brakes do not operate, and the warning system is not activated.Probable causes
The brake group within the axle housing is damaged.
The lines to the rear service brakes are obstructed.
The rear circuit of the service brake control valve is faulty. Problem 4The service brakes slip, and the warning system is not activated.Probable causes
One or both axles contain an incorrect hydraulic oil additive.
The brake disc in the axle housing is worn. Problem 5The service brakes are not applied evenly.Probable causes
The brake disc and associated components in the axle housing are excessively worn.
The brake valve is