PUMP GP-UNIT INJECTOR HYD 3891186 - Caterpillar

Illustration 1 g01348951
(1) Valve Body
(2) Port (P) (Discharge from pump)
(3) Pressure Reducing Valve
(4) Relief Valve
(5) Port (T) (tank)
(6) Port (CP) (pilot supply oil)
(7) Solenoid Valve for Implement Lockout
(8) Port for Accumulator (ACC)
(9) Check Valve
(10) Screen
Illustration 2 g03661667
Location of manifold and reducing valve
The manifold for the pressure reducing valve is located toward the rear of the machine under the platform. The manifold for the pressure reducing valve contains a pressure reducing valve (3), a relief valve (4), an accumulator port (8), a check valve (9), and screen (10).The pressure reducing valve reduces the implement hydraulic pressure to a maximum of 3275 175 kPa (475 25 psi).A pump discharge line attaches at port (P). The pressure reducing valve reduces the system pressure to pilot supply pressure. The reduced pressure is termed pilot supply oil. Pilot supply oil exits the pressure reducing valve at port (CP). Next, the pilot supply oil proceeds to the shutoff valve.The pressure reducing valve is coupled with the accumulator. The accumulator attaches to the manifold at port (8). For more information about the accumulator, refer to Systems Operation, "Accumulator".The relief valve provides a secondary relief in case of pressure spikes and over pressurization of the pilot system. The check valve stops backflow of oil during conditions of low pump discharge pressure.The accumulator and the check valve maintain supply pressure during momentary drops in pump pressure. This system will permit the attachment to be lowered up to 1.5 minutes after the engine is off.There are three methods of lowering attachments after the engine has been off for 1.5 minutes.
Use the pilot control lever to lower the attachments. Crank the engine in order to operate the control lever.
Use the 7H-1680 Compressor Assembly to provide pilot pressure to the valve. Turn the shutoff valve to the UNLOCK position. If the shutoff valve is not in the UNLOCK position, the oil will be pumped to the hydraulic tank. Oil is applied through the pressure tap for pilot supply after the pressure reducing valve. The pressure tap is located under an access plate on the right fender. Refer to Testing and Adjusting, "Pressure Taps" for the location of the pressure tap.
Use the 164-0758 Bolt (9/16 inch by 18 by 2 inch) that is mounted behind the access plate on the front of the right console to activate the valve spool.Lockout of the control levers is accomplished in the following manner. Solenoid valve (7) operates the shutoff valve that is in the manifold. The solenoid valve (7) is energized when the machine is running. When the solenoid valve is energized, the shutoff valve is moved to the UNLOCK position. Pilot supply oil from the pressure reducing valve enters the shutoff valve of the manifold. In the UNLOCK position, the shutoff valve directs pilot supply oil to the pilot control valve. In the LOCK position, the line from the pressure reducing valve is blocked and the oil is diverted to the tank line. This allows the oil from the pilot control