VALVE-BYPASS 1888726 - Caterpillar

Personal injury or death can result from sudden machine movement.Sudden movement of the machine can cause injury to persons on or near the machine.To prevent injury or death, make sure that the area around the machine is clear of personnel and obstructions before operating the machine.
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 attachments have been lowered, 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, "Caterpillar Tools and Shop Products Guide" for tools and supplies suitable to collect and contain fluids on Caterpillar products.Dispose of all fluids according to local regulations and mandates.
Operational Checks
Note: The checks during operation can be used to find leakage in the system. These checks can also be used to find a bad valve, a bad pump, or a bad motor. Probable Causes of Problems in the Steering System
ProblemThe gear pump is noisy and the steering cylinder rods do not move easily. Probable Cause
Air in the steering hydraulic circuit
The gear pump is worn.
There is a loose connection in the oil line that is connected to the inlet side of the steering pump.
The hydraulic oil level is low.
Viscosity of the hydraulic oil is not correct.ProblemToo much force is needed to turn the steering wheel.Probable Cause
The relief valve is open.
The hydraulic oil level is low.
The oil pressure in the gear pump is too low.
Metering pump covers are too tight.
The metering pump is defective.
The hydraulic oil is cold.
Alignment of steering column is not correct.ProblemThe machine does not turn when the steering wheel is turned.Probable Cause
The hydraulic oil level is low.
There is air in the hydraulic system.
There is dirt in the hydraulic system.
The operation of the gear pump is not correct.
The frame articulation is locked because the lock pin is in the hole in the yoke.
One of the steering cylinders has worn piston rings.ProblemThe machine turns slowly in both directions. Probable Cause
There is not enough oil flow from the gear pump.
The suction line in the gear pump is restricted.
Metering pump operation is not correct.
Seal leakage in the steering cylinders.
The priority valve spool that is inside the gear pump does not allow enough oil to go to the metering pump.
The pressure in the steering circuit is too low.ProblemMachine turns slowly in one direction. Probable Cause
There is a restriction in the metering pump.ProblemThe metering pump does not return to the center position correctly. Probable Cause
Metering pump covers are too