TM 5-3805-258-24-1
H Y D R A U L I C
S Y S T E M
S Y S T E M S O P E R A T I O N
LIFT AND TILT PILOT VALVE
(Lift and Lower Stems in HOLD Position)
1. Actuator. 2. Lift control shaft. 3. Plunger (lower). 4.
Plunger
(lift).
5.
Retainer.
6.
Retainer.
7.
Metering
spring. 8. Metaring spring. 9. Centering spring. 10. Cen-
tering spring. 11. Tank passage. 12. Lower stem. 13. Lift
stare. 14. Holes. 15. Holaa. 16. Vent passage. 17. Tank
paaaaga. 18. Passage to lift valve spool. 19. Passage to lift
valva spool. 20. Pump (supply) passage. 21. Passage to
tilt valve spool (dump stem). 22. Passage to tilt valve spool
(tilt back stem).
Spring (10) pushes up on retainer (5) and plunger
(3). Spring (8) holds lower stem (12) down against
retainer (5). Spring (9) pushes upon retainer (6) and
plunger (4). Spring (7) holds lift stem (13) down
against retainer (6). There are spacers between the
retainers and plungers that are used to change the
force of springs (7) and (8).
LIFT AND TILT PILOT VALVE
(Lift Stem in RAISE Position)
1. Actuator. 2. Lift control shaft. 4. Plunger (lift). 6. Re-
tainer. 7. Metering spring. 6. Metering spring. 9. Center-
ing spring. 11. Tank passage. 12. Lower stem. 13. Lift
stem. 14. Holes. 15. Holes. 18. Passage to lift valve
spool. 19. Passaga to lift valve spool. 20. Pump (supply)
passage.
When the lift control lever is moved into RAISE
position, the control lever turns shaft (2) and actua-
tor (1) in the direction shown. The actuator pushes
plunger (4) down against the force of spring (9). Lift
stem (13) moves down with the plunger. The oil from
pump passage (20) now goes through holes (15) and
out passage (19) to one end of the lift valve spool. The
pressure of this oil on the end of the lift valve spool
moves the spool into RAISE position.
The oil from the chamber at the opposite end of the
lift valve spool comes back through passage (18).
This oil goes through holes (14) of lower stem (12)
into tank passage (11).
Oil pressure in passage (19) pushes up against lift
stem (13) and spring (7). A small pressure increase
in passage (19) pushes lift stem (13) up against the
force of spring (7). The flow of pressure oil through
holes (15) and passage (19) is stopped [the pressure
3-96
