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| Illustration 1 | g00818129 |
(1) Valve Body (2) Pressure Reducing Valve (3) Relief Valve (4) Port for Accumulator (ACC) (5) Screen (6) Check Valve (7) Plug and Seal (P) Port (Discharge from pump) (T) Port (tank) (CP) Port (pilot supply oil) | |
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| Illustration 2 | g00773650 |
Location of manifold and reducing valve | |
The manifold and reducing valve is located behind an access panel on the right side of the operator station. The manifold and reducing valve contains an accumulator port (4), pressure reducing valve (2), relief valve (3), screen (5), and a check valve (6) .
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 (4). 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. You need to 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. Pilot supply oil from the pressure reducing valve enters the shutoff valve. 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 line to the pilot control valve is diverted to the tank line. This allows the oil from the pilot control valves to drain to the hydraulic tank. Also, when the knob is turned to the LOCK position a switch deactivates a coil on the pilot valve and a second switch activates a lamp on the instrument panel. When the coil is activated, the coil is used to hold controls for the FLOAT position.