J&M 220 Operating And Maintenance Manual - page 53
MODEL 220
HYDRAULIC
IMPACT HAMMER
V. HYDRAULIC
CIRCUITRY
C.
OTHER
Returning oil is filtered by the return filters (F2) before entering the reservoir.
INDICATOR GAGE (GA5) shows condition of FILTER (F2).
The shut-off VALVE (MV1) may be closed to permit removal of the pumps (P1 and
P2) without draining the reservoir. CAUTION: DO NO start engine with MV1
closed.
The oil cooler (HE) cools the hydraulic oil returning from the hammer.
65 PSI Check VALVE (CV5) prevents excess pressure from damaging HEAT
EXCHANGER (HE).
A manual pump (MP) is provided to fill the hydraulic reservoir. A CHECK VALVE
(CV2) prevents loss of oil from the reservoir back through the manual pump.
A temperature switch (TS) located in the reservoir operates the hydraulic oil cold
light.
Check valve CV8 and orifice OF2 control the movement of the DUMP VALVE,
allowing rapid closing and slower opening.
CONTROL VALVE orifice OF1 provides controlled leakage of pilot signals.
Check valve CV7 prevents loss of pilot pressure signal into the CONTROL VALVE.
V-3