TM 5-3805-258-24-1
H Y D R A U L I C
S Y S T E M
tank. In this way, the oil from the rod end of the tilt
cylinder bypasses the lift circuit and prevents TILT
BACK and RAISE operations at the same time.
NOTE: When tilt valve spool (11) is fully in TILT
BACK position, no implement oil goes to lift valve
spool (16). The lift circuit will not operate.
DUMP Operation
When the tilt control lever is moved to DUMP
position, pilot oil goes to chamber (12) and tilt valve
spool (11) moves to the left. Oil flow to the tilt
cylinder in DUMP position is the reverse of oil flow
in TILT BACK position. Implement oil is sent from
inlet passage (10) to load check valve (9). The load
check valve opens when inlet pressure becomes
greater than the force of spring (8) and the rod end
pressure of the tilt cylinder. The oil now goes through
S Y S T E M S O P E R A T I O N
passage (7) and out passage (5) to the rod end of the
tilt cylinder. This causes the bucket to dump. During
this operation when the tilt cylinder rod retracts
faster than the pump can provide oil to the rod end,
make-up valve (4) moves against spring (3) and per-
mits oil from the tank to add to the implement oil.
This prevents cavitation (vacuum) in the system.
Oil from the head end of the tilt cylinder comes
through passage (6), goes around tilt valve spool
(11), lift valve spool (16) and through outlet passage
(15) to the hydraulic tank. The oil from the head end
of the tilt cylinder also bypasses the lift circuit and
prevents DUMP and RAISE operations at the same
time.
NOTE: When tilt valve spool (11) is fully in DUMP
position, no implement oil goes to lift valve spool
(16). The lift circuit will not operate.
Lift Valve Spool
LIFT AND TILT CONTROL VALVE
(Lift Valve Spool In RAISE And Tilt Valve Spool In HOLD)
10. Inlet paaaage for
16. Lift valve spool.
21. Spring.
implement oil.
17. Chamber for pilot oil.
22. Paaaage to rod end of
11. Tilt valve apooL
18. Springs,
lift cylinders.
13. Paaaage.
19. Make-up valve for rod
23. Paaaage to head end of
14. Paaaage.
end of lift cylinders.
lift cylinders.
15. Outlet paaaage to
20. Vent paasage to lift and
hydraulic tank.
tilt pilot valve.
24. Passage.
25. Load check valve for lift
circuit.
26. Spring.
27. Chamber.
3-104
