STRUCTURE, FUNCTION, & MAINTENANCE STANDARD SELF PRESSURE REDUCING VALVE 12 4. When abnormally high pressure is generated If the PR pressure on the self-pressure reducing valve rises high abnormally, ball (16) separates from the seat against the force of spring (15) and the hydraulic oil flows from output port PR to TS. Accordingly, the PR pressure lowers. By this oper- ation, the hydraulic devices (PPC valves, solenoid valves, etc.) are protected from abnormal pressure. (See Fig. 4.) PC210/240-7K 10-85