CONE 0052338 - Caterpillar

Hydraulic oil pressure can remain in the hydraulic system on this machine after the engine and pump have been stopped. Serious injury can result if this pressure is not released before any service is done on the hydraulic systems. In order to prevent possible injury, release the hydraulic system pressure before working on any fitting, hose, or hydraulic component.Lower all attachments to the ground before service is started. If the hydraulic system must be serviced, tested, or adjusted with the attachment in the raised position, the attachments and lift cylinders must be supported properly.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.
Specifications
Table 1
Valve Pressures
Date Equipment ID Code
Item Specification Actual
Pressure Reducing Valve (High Idle) 3275 175 kPa (475 25 psi)
Relief Valve 6483 345 kPa (940 50 psi) Introduction
The pressure reducing valve reduces the implement hydraulic pressure. The relief valve prevents excessive pressure buildup in the pilot system. If a high-pressure situation occurs, the relief valve will open. Excess pressure is relieved through the valve.The pressure in the pilot system controls the response of the implements. Low pilot pressure produces poor response in the implement control levers. High pilot pressure produces extreme sensitivity in the implement control levers.The following test procedure will verify whether the pressure setting for the pilot pressure is within the specified limit. The following adjustment procedure will explain the procedure for adjusting the pilot pressure.Pilot pressure is controlled by the pressure reducing valve, which is located in the pilot manifold.Required Tools
Illustration 1 g02571852
Tooling (A) 198-4240 Digital Pressure Indicator Gp
Table 2
Required Tools
Tool Item Qty Part No Description
A 198-4240 Digital Pressure Indicator Gp
A1 1 198-4234 Digital Indicator
A2 1 198-4237 Pressure Sensor Gp
(0 to 3,445 kPa (0 to 500 psi))
A3 1 198-4236 Adapter Cable As Test Preparation - Pressure Reducing Valve
The pressure reducing valve is located behind an access door on the right fender