DUMP Position With Engine Off

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 DUMP Position LIFT AND TILT PILOT VALVE (Dump Stem In DUMP Position) 11. Tank passage. 20. Pump (supply) passage. 21. Pas- sage to tilt valve spool. 22. Passage to tilt valve spool. 24. Actuator. 25. Tilt control shaft. 26. Plunger (dump). 27. Plunger (tilt back). 28. Retainer. 29. Retainer. 30. Meter- ing spring. 31. Metering spring. 32. Centering spring. 33. Centering spring. 34. Tilt back stem. 35. Dump stem. 36. Holes. 37. Holes. When the tilt control lever is moved to DUMP position, shaft (25) and actuator (24) turn in a coun- terclockwise direction (as shown). The movement of the plunger and stem in the pilot valve is the same as in LOWER position. Dump stem (35) moves down and oil from pump passage (20) goes through holes (37). The oil goes out passage (21) to one end of the tilt valve spool. The tilt valve spool moves into DUMP position. The oil from the chamber at the opposite end of the tilt valve spool comes back through passage (22). This oil goes through holes (36) of tilt back stem (34) into tank passage (11). DUMP Position With Engine Off When the lift arms are raised, the bucket can be dumped with the engine off. The oil supply comes from the head end of the lift cylinders into pump passage (20). When the tilt control lever is moved to DUMP position, the bucket will dump. The operation of dump stem (35) is the same as in DUMP position when the engine is running. The weight of the bucket causes it to dump. NOTE: See LOWER Position With Engine Off. ATTACHMENT (THIRD) PILOT VALVE This pilot valve is for the operation of an addi- tional or third circuit to control an attachment. (log fork, side dump or multi-purpose bucket, etc.). This pilot valve is also controlled manually by the operator. It gets oil from the lift and tilt pilot valve and sends it to the attachment valve spool of the attachment (three spool) control valve. The attach- ment valve spool sends oil to the attachment cylinder or cylinders. There are two valve stems (of the pres- sure metering type) in the attachment pilot valve. Both stems are used for each operation. Open or raise stem (14) is the same shape and operates the same as the raise stem of the lift and tilt pilot valve. Close or lower stem (15) is longer than open or raise stem (14), but it operates the same way. HOLD Position When the attachment control lever is in HOLD position, plungers (2) and (3) are in the same posi- tion. The plungers do not push up against actuator (1) in the hold position. Pressure oil from the pilot pump section goes through pump passage (13) and is stopped by the position of stems (14) and (15). Holes (11) and (12) are open to tank passage (6). Spring (9) pushes up on retainer (4) and plunger (2). Spring (8) holds close or lower stem (15) down against retainer (4). Spring (10) pushes up on re- tainer (5) and plunger (3). Spring (7) holds open or raise stem (14) down against retainer (5). There are spacers between the retainers and plungers that are used to change the force of springs (7) and (8). 3-99

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