Tilt 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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H Y D R A U L I C S Y S T E M TM 5-3805-258-24-1 S Y S T E M S O P E R A T I O N LIFT AND TILT CONTROL Tilt Valve Spool VALVE LIFT AND TILT CONTROL VALVE (Lift Valve Spool in HOLD and Tilt Valve Spool in TILT BACK) 1. Chamber for pilot oil. 6. Passage to head end of 10. Inlet paaaage for 2. Springs. tilt cylinder. implement oil. 3. Spring. 7. Paasage. 11. Tilt valve apool. 4. Make-up valve for rod 8. Spring. 12. Chamber for pilot end of tilt cylinder. 9. Load check valve for tilt 13. Passage. 5. Paasage to rod end of circuit. tilt cylinder. Oil from the implement pump section goes TILT BACK Operation 14. Passage. 15. Outlet paasage to hydraulic tank. oil. 16. Lift valve spool. through inlet passage (10) to tilt valve spool (11). On machines with an attachment (three spool) control valve, the pump flow goes to the attachment valve spool before it goes to the lift and tilt valve spools. The tilt valve spool is a spring-centered, open center, pilot operated spool with three positions: TILT BACK, HOLD and DUMP. Springs (2) keep the spool in HOLD position when there is no pilot pres- sure oil in chambers (1) and (12). Movement of the spool is controlled by pilot pressure oil from the lift and tilt pilot valve in chambers (1) and (12). When the tilt control lever is moved to TILT BACK position, pilot oil is sent to chamber (1) and tilt valve spool (11) moves to the right. Implement oil is sent from inlet passage (10) to load check valve (9). The load check valve prevents reverse oil flow which can cause cylinder drift or load loss. Load check valve (9) does not open until the oil pressure becomes greater than the force of spring (8) and the head end pressure of the tilt cylinder. The oil opens the load check valve, goes through passage (7) and out pas- sage (6) to the head end of the tilt cylinder. This When tilt valve spool (11) is in HOLD position, causes the bucket to tilt back. implement oil goes from inlet passage (10), through passage (14) and outlet passage (15) to the hydraulic Oil from the rod end of the tilt cylinder comes tank. The position of the spool holds (blocks) the oil through passage (5), around tilt valve spool (11), in both ends of the tilt cylinder and keeps the cylinder through passage (13), around lift valve spool (16) from movement. and through outlet passage (15) to the hydraulic 3-103

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