STEP AS 3396737 - Caterpillar

Illustration 1 g00297171
Side View of the pilot valve (1) Tilt valve. (2) Lift valve. (3) Auxiliary valve. (4) Return port to the hydraulic oil tank. (5) Supply port from the pilot valve (oil manifold).When the engine is running oil flows from the pilot/brake pump to the pilot valve (oil manifold). The pilot valve (oil manifold) reduces the pressure at port (5) to 2600 200 kPa (375 30 psi).If you stop the engine or if the implement pump fails with the lift arm in the RAISED position, the lift arms can still be lowered. The pilot valve (oil manifold) supplies pilot oil to the pilot valve at reduced pressure. The reduced pressure at port (5) is 2070 200 kPa (300 30 psi).
Illustration 2 g00308453
Hydraulic Lever Lock (6) LOCKED position. (7) UNLOCKED position.When the hydraulic lever lock is in LOCKED position (6), the flow of oil to port (5) is blocked. When the hydraulic lever lock is in UNLOCKED position (7) the oil flows through the ball valve to port (5) .Note: The operation of tilt valve (1), lift valve (2), and auxiliary valve (3) are similar. Only the operation of the tilt valve is described.Tilt valve (1) has a detent in the TILT BACK position. Lift valve (2) has detents in both the LOWER position and the RAISE position. Auxiliary valve (3) does not have a DETENT position.
Illustration 3 g00297172
Tilt Valve (8) Pivot plate. (9) Upper plunger (TILT BACK). (10) Upper plunger (DUMP). (11) Coil assembly for kickout. (12) Retainer. (13) Retainer. (14) Centering spring. (15) Centering spring. (16) Lower plunger. (17) Lower plunger. (18) Retainer. (19) Retainer. (20) Centering spring. (21) Centering spring. (22) Metering spring. (23) Metering spring. (24) Metering stem. (25) Metering stem. (26) Port to the main control valve. (27) Port to the hydraulic oil tank. (28) Port from the pilot valve (oil manifold). (29) Port to the main control valve.HOLD Position
When the tilt valve is in the HOLD position, centering springs (14), (15), (20), and (21) keep pivot plate (8) in the CENTERED position. Pilot pressure oil flows from port (28) to metering stems (24) and (25) .Metering stems (24) and (25) prevent oil from flowing to ports (26) and (29). The implements will not function. This causes the oil to flow through port (27). The oil then returns to the hydraulic oil tank.DUMP Position
When the tilt control lever is moved to the DUMP position, pivot plate (8) causes upper plunger (10) to move downward. As upper plunger (10) moves downward, the force on retainer (12) overcomes spring (14). This allows upper plunger (10) to contact lower plunger (16) .Upper plunger (10) causes lower plunger (16) to move downward. As lower plunger (16) moves downward, retainer (18) is forced to overcome spring (20). Also, metering spring (22) and metering stem (24) move downward.When metering stem (24) moves downward, holes in the metering stem allow oil to flow from port (28), out of port (26) and to the main control valve.When the tilt control