Lift Valve Spool

TM-5-3805-258-24-1 Loader Scoop Type DED 4x4 Articulated Frame Steer 2 1/2 Cubic Yard Bucket (CCE) Airborne/Airmobile Manual
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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

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