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| Illustration 1 | g00640669 |
Schematic for the Main Hydraulic System (1) Main control valve (tilt and auxiliary) (2) Tilt cylinders. (3) Auxiliary cylinders (third function) (4) Ball valve (attachment coupler) (5) Attachment coupler cylinder (6) Auxiliary cylinders (fourth function) (7) Main control valve (lift and auxiliary) (8) Lift cylinders (9) Shuttle valve (ride control) (10) Line relief valve for the head end of the tilt cylinders (11) Line relief valve for the rod end of the tilt cylinders (12) Line relief valve for the rod end of the auxiliary cylinders (13) Main relief valve (14) Line relief valve for the head end of the auxiliary cylinders (15) Auxiliary valve spool (fourth function) (16) Line relief valve for the head end of the auxiliary cylinders (17) Lift valve spool (18) Ride control diverter valve (19) Check valve (20) Line relief valve for the rod end of the auxiliary cylinders (21) Check valve (22) Tilt valve spool (23) Auxiliary valve spool (third function) (24) Check valve (25) Check valve (26) Ride control relief valve (27) Pilot valve (oil manifold) (28) Ball valve (hydraulic lever lock) (29) Diverter valves (30) Pilot control valve (31) Implement pump (32) Pilot/brake pump (33) Hydraulic oil tank (34) Main relief valve (AA) Pressure tap for main implement pressure to the main control valve (lift and auxiliary) (BB) Pressure tap for implement pilot pressure (CC) Pressure tap for main implement pressure (A) Signal pressure line for the steering system (B) Steering supply | |
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| Illustration 2 | g00487800 |
Front View of Machine (1) Main control valve (tilt and auxiliary). (7) Main control valve (lift and auxiliary). | |
The main hydraulic system is made up of the following components: two main control valves (1) and (7), auxiliary cylinders (3) and (6), tilt cylinders (2), lift cylinders (8), ball valve (4), attachment coupler cylinder (5), implement pump (31), hydraulic oil tank (33) and main relief valve (13).
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| Illustration 3 | g00487928 |
Top View of Main Control Valve (Tilt and Auxiliary) (1) Main control valve (tilt and third auxiliary). (10) Line relief valve for the rod end of the tilt cylinders. (11) Line relief valve for the head end of the tilt cylinders. (13) Main relief valve. (14) Line relief valve for the head end of the auxiliary cylinders. (20) Line relief valve for the rod end of the auxiliary cylinders. | |
Main control valve (1) controls the high pressure oil to tilt cylinders (2), and auxiliary cylinders (3) and (6). Main control valve (1) also controls the high pressure oil to attachment coupler cylinder (5).
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| Illustration 4 | g00483440 |
Top View of the Flow Control and Relief Valve Group (12) Line relief valve for the rod end of the auxiliary cylinders. (15) Auxiliary valve spool (fourth function). (16) Line relief valve for the head end of the auxiliary cylinders. (17) Lift valve spool. (18) Ride control diverter valve. (27) Pilot valve (oil manifold). (BB) Pressure tap for pilot pressure. | |
Main control valve (7) controls the high pressure oil to lift cylinders (8) and auxiliary cylinders (6) .
Implement pump (31) supplies the high pressure oil that operates auxiliary cylinders (3) and (6), attachment coupler cylinder (5), tilt cylinders (2), and lift cylinders (8). Oil flows from the implement pump to main control valves (1) and (7) .
Main relief valve (13) controls the pressure in the main hydraulic system. Main relief valve (13) opens when the oil pressure from implement pump (31) rises above the relief pressure setting.
Pilot pressure oil flows from pilot/brake pump (32) to pilot valve (27). Pilot oil from pilot valve (27) flows to pilot control valve (30). Pilot control valve (30) causes valve spools (15), (17), and (22) to move when the control levers are moved.
Tilt valve spool (22) has three positions: TILT BACK position, HOLD position and DUMP position. When tilt valve spool (22) moves to the TILT BACK position, high pressure oil flows through the tilt valve spool to the rod end of the tilt cylinders. Oil from the head end of the tilt cylinders flows through the tilt valve spool. This oil is used with supply oil that is going to the rod end of the tilt cylinder.
In the HOLD position, all of the oil flow returns to the hydraulic oil tank. When the tilt valve spool moves to the DUMP position, high pressure oil flows through the tilt valve spool to the head end of the tilt cylinders. Oil from the rod end of the tilt cylinders flows through the tilt valve spool back to the hydraulic oil tank.
Lift valve spool (17) has three positions: RAISE position, HOLD position and LOWER position. In the RAISE position, high pressure oil flows to the head end of the lift cylinders. In the HOLD position, all of the oil flow returns to the hydraulic oil tank. In the LOWER position, high pressure oil flows to the rod end of the lift cylinders.
When the lift control lever in the cab is placed in the FLOAT position the lift valve spool remains in the LOWER position. A float valve in pilot control valve (27) opens in order to allow the bucket to rest on the ground.
In the LOWER position, high pressure oil flows to the rod end of the lift cylinders. In the HOLD position, all of the oil flow returns to the hydraulic oil tank. In the RAISE position, high pressure oil flows to the head end of the lift cylinders.
Auxiliary valve spool (23) has three positions: LOCK position, HOLD position and UNLOCK position. When auxiliary valve spool (23) moves to the LOCK position, high pressure oil flows through the auxiliary valve spool to the head end of attachment coupler cylinder (5). Oil from the rod end of the attachment coupler cylinder flows through the auxiliary valve spool back to the hydraulic oil tank.
In the HOLD position, all of the oil flow returns to the hydraulic oil tank. When auxiliary valve spool (23) moves to the UNLOCK position, high pressure oil flows through the auxiliary valve spool to the rod end of the attachment coupler cylinder. Oil from the head end of the coupler cylinder flows through the auxiliary valve spool back to the hydraulic oil tank.
Auxiliary cylinders (3) also use auxiliary valve spool (23). When auxiliary valve spool (23) moves to the LOCK position, high pressure oil flows through the auxiliary valve spool to the rod end of auxiliary cylinders (3). Oil from the head end of the auxiliary cylinders flows through the auxiliary valve spool back to the hydraulic oil tank.
In the HOLD position, all of the oil flow returns to the hydraulic oil tank. When auxiliary valve spool (23) moves to the UNLOCK position, high pressure oil flows through the auxiliary valve spool to the head end of the auxiliary cylinders. Oil from the rod end of the auxiliary cylinders flows through the auxiliary valve spool back to the hydraulic oil tank.
You can close ball valve (4) in order to isolate attachment coupler cylinder (5) .
Auxiliary cylinders (6) can be used if you push the fourth function switch to the ON position. Diverter valve (29) routes the pilot oil to auxiliary valve spool (15) which controls auxiliary cylinders (6). The tilt lever is used to control auxiliary cylinders (6).
The auxiliary circuits, the tilt circuit, and the lift circuit have check valves that are located inside the main control valve. Check valves (19), (21), (24) and (25) prevent reverse oil flow through the main control valve. Reverse flow through the main control valve could cause cylinder drift.