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4. Maintenance 4.6 Pressure relief valve
Thin rod
Relief Valve DisassemblyRelief Valve Disassembly
Relief Valve DisassemblyRelief Valve Disassembly
Relief Valve Disassembly
1. Remove manual override lever if fitted.
2. Remove screws (25) and valve housing (24).
3. Remove notched nut(s) (23) and spring adjuster (21). If springs are still compressed when the notched nut reaches end of thread,
release the spring adjuster screws (26).
4. Remove springs (18) (models S1-5), spring stacks (models S6), screws and valve guide (16).
5. Remove circlip (14) and pneumatic piston (12).
6. Remove screws, backstop disc (6) and hydraulic piston (2).
7. Unscrew hydraulic piston (2) from valve shaft (10) and remove O-rings (3, 7, 11 and 13).
Relief Valve Assembly
New o-rings should be fitted during assembly.
Clean components before fitting; check there is no damage to faces.
1. Lubricate all o-rings.
2. Fit O-ring (7) to backstop disc (6) and fit backstop disc to valve shaft (10).
3. Fit O-ring (3) to hydraulic piston (2) and screw onto valve shaft.
4. Locate assembly into rotorcase cover, replace backstop disc screws (9).
5. Fit pneumatic piston o-rings (11 and 13) and locate assembly on valve shaft. Replace circlip (14) and springs (18).
(Models S6 pumps only - each spring stack should contain an equal amount of springs, noting correct orientation).
Place valve guide (16) over springs and replace screws (26).
6. Fit spring adjuster (21) and notched nut (23), valve housing (24) and screw (25).
7. Replace manual override lever if applicable.
Valve Adjustment
The relief valve will require setting to suit duty requirements.
Note: A gauge is required to measure discharge pressure during
adjustment
1. Stop the pump
2. Remove valve housing (24).
3. Release notched nut(s) (23) to end of thread.
4. Insert a thin rod into valve guide (16) and mark to indicate
closed position.
5. Start pump and increase pressure noting pressure gauge
reading when the rod starts to move. This indicates the valve
is beginning to open.
6. Tighten the notched nut gradually until desired system
pressure is achieved. (Model S6 pump only - evenly tighten
the spring stack nuts after adjusting the notched nut).
7. Apply thread locking adhesive to the notched nut after
relief valve is set.
8. If pneumatic override is required connect air supply and
adjust pressure until valve opens. Check piston reseats
when air supply is disconnected.
9. Replace valve housing and screws.
