For additional information on the hydraulic system, refer to Hydraulic Schematic, KENR6525.
HOLD Position
Note: Detailed oil flow is not shown for the HOLD position. Refer to Illustration 1 for references to components.
When the engine is running, the charge pump (not shown) sends pilot oil to pressure accumulator (19) through line (20). Pilot oil is available to the electrohydraulic pilot solenoids.
The valve spools in the HOLD position block the passages to the rod end and to the head end of the hydraulic cylinders. The oil is trapped and the implements do not move. In the HOLD position, the spring centers the valve spool.
Raise Operation
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| Illustration 1 | g01932113 |
Raise operation (2) Dead electronic lower valve (Lift circuit) (3) Bucket lift control valve (4) Lift cylinders (5) Makeup valve (lift rod end) (6) Line relief valve (lift head end) (7) Bucket tilt control valve (8) Tilt cylinder (9) Line relief valve (tilt rod end) (10) Line relief valve (tilt head end) (18) Anti-drift valve (19) Accumulator (20) Flow from the charge circuit of the right drive pump (22) Margin relief valve (24) Pilot control solenoid (26) Implement pump (27) Hydraulic oil tank | |
When the lift control lever is moved to the RAISE position, the solenoids allow pilot oil to flow to the right end of lift valve spool (3). This causes the valve spool to move to the left.
The movement of lift valve spool (3) causes the load signal pressure to increase. When signal pressure increases the flow at implement pump (26) increases. The oil from implement pump (26) now flows to the head end of lift cylinders (4). The cylinder pistons and rods extend. The lift cylinders cause the bucket to raise. The movement of the cylinder pistons and rods pushes the oil out of the rod end of the lift cylinders. The oil from the rod end flows into the valve bank. Then, the oil travels to hydraulic tank (27) .
When the lift control lever is released, the lever moves back to the HOLD position. The solenoids divert the flow of pilot oil from lift valve spool (3) back to tank (27). This causes lift valve spool (3) to move back into the HOLD position. The pilot oil at the right end of the lift valve spool flows back through the valve bank to hydraulic tank (27). The oil in lift cylinders (4) is blocked by lift valve spool (3). Movement of the cylinder pistons and rods stops. The lift arms and the bucket are held in position until the lift control lever is moved.
Lower Operation
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| Illustration 2 | g01932114 |
Lower Operation (2) Dead electronic lower valve (Lift circuit) (3) Bucket lift control valve (4) Lift cylinders (5) Makeup valve (lift rod end) (6) Line relief valve (lift head end) (7) Bucket tilt control valve (8) Tilt cylinder (9) Line relief valve (tilt rod end) (10) Line relief valve (tilt head end) (18) Anti-drift valve (19) Accumulator (20) Flow from the charge circuit of the right drive pump (22) Margin relief valve (24) Pilot control solenoid (26) Implement pump (27) Hydraulic oil tank | |
When the lift control lever is moved to the LOWER position, the solenoids allow pilot oil to flow to the left end of the lift valve spool. This causes lift valve spool (3) to move to the right.
The movement of lift valve spool (3) causes the load signal pressure to increase. When signal pressure increases the flow at implement pump (26) increases. The oil from implement pump (26) now flows to the rod end of lift cylinders (4). The cylinder pistons and rods retract.
The lift cylinders cause the bucket to lower. The movement of the cylinder pistons and rods pushes the oil out of the head end of the lift cylinders. The oil from the head end then flows into the valve bank. Then, the oil travels to hydraulic tank (27) .
When the lift control lever is released, the lever moves back to the HOLD position. The solenoids divert the flow of pilot oil from lift valve spool (3) back to tank (27). This causes lift valve spool (3) to move back into the HOLD position. The pilot oil at the left end of the lift valve spool flows back through the valve bank to hydraulic tank (27). The oil in lift cylinders (4) is blocked by lift valve spool (3). Movement of the cylinder pistons and rods stops. The lift arms and the bucket are held in position until the lift control lever is moved.
Float Operation
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| Illustration 3 | g01932115 |
Float operation (2) Dead electronic lower valve (Lift circuit) (3) Bucket lift control valve (4) Lift cylinders (5) Makeup valve (lift rod end) (6) Line relief valve (lift head end) (7) Bucket tilt control valve (8) Tilt cylinder (9) Line relief valve (tilt rod end) (10) Line relief valve (tilt head end) (18) Anti-drift valve (19) Accumulator (20) Flow from the charge circuit of the right drive pump (22) Margin relief valve (24) Pilot control solenoid (26) Implement pump (27) Hydraulic oil tank | |
When the lift control lever is moved to the FLOAT detent position, the pilot oil is directed to the left side of lift valve spool (3). Lift valve spool (3) then shifts to the FLOAT position. Both ends of lift cylinders (4) are now open to hydraulic tank (27) and the FLOAT operation can occur. The movement of the bucket is controlled by external forces during the FLOAT operation.
When the lift control lever is moved to the FLOAT position, the machine is commanded to float to the lower kickout. When the lift control lever is moved consecutively into the FLOAT position, the machine is quickly put into the FLOAT position.
During the FLOAT operation, electronic snubbing is used in order to help prevent the lift cylinders from stopping immediately.
Dead Engine Lower
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| Illustration 4 | g01932116 |
Dead Engine Lower (2) Dead electronic lower valve (Lift circuit) (3) Bucket lift control valve (4) Lift cylinders (5) Makeup valve (lift rod end) (6) Line relief valve (lift head end) (7) Bucket tilt control valve (8) Tilt cylinder (9) Line relief valve (tilt rod end) (10) Line relief valve (tilt head end) (18) Anti-drift valve (19) Accumulator (20) Flow from the charge circuit of the right drive pump (22) Margin relief valve (24) Pilot control solenoid (26) Implement pump (27) Hydraulic oil tank | |
The implement circuit may still be operated when the engine is dead. Accumulator (19) stores potential energy while the engine is running by accumulating a quantity of pressurized hydraulic oil. When the engine is dead, the accumulator supplies this oil to the pilot valve.
When the operator moves the lift control lever, oil flows from accumulator (19) to the end of lift valve spool (3). The spool is shifted and the oil that was trapped in the lift cylinders flows back to the hydraulic tank as gravity lowers the attachment to the ground.
When the front of the machine is off of the ground, there is pressure on the rod end of lift cylinders (4). Oil from the accumulator can now be used as pilot oil in order to shift lift valve spool (3) to the RAISE position. The oil that was trapped in the rod end of the lift cylinders flows back to the hydraulic tank as the machine lowers.
Dead Electronic Lower
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| Illustration 5 | g01932117 |
Dead Electronic Lower (2) Dead electronic lower valve (Lift circuit) (3) Bucket lift control valve (4) Lift cylinders (5) Makeup valve (lift rod end) (6) Line relief valve (lift head end) (7) Bucket tilt control valve (8) Tilt cylinder (9) Line relief valve (tilt rod end) (10) Line relief valve (tilt head end) (18) Anti-drift valve (19) Accumulator (20) Flow from the charge circuit of the right drive pump (22) Margin relief valve (24) Pilot control solenoid (26) Implement pump (27) Hydraulic oil tank | |
If the engine is dead and the electronics are dead then the oil pressure that is stored in the accumulator is not usable for lowering lift cylinders (4). If this is the case then dead electronic lower valve (2) needs to be turned on and the oil from lift cylinders (4) flows back to the tank as gravity lowers the attachment.
Note: Dead electronic lower valve (2) is located under the floorplate of the cab on the right front side of the frame.
Dead Accumulator and Dead Engine Lower
If the accumulator has no charge then use the process that is located in "Dead Electronic Lower" in order to lower the attachment.
Note: Dead electronic lower valve (2) is located under the floorplate of the cab on the right front side of the frame.
Backdragging Operation
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| Illustration 6 | g01932119 |
Backdragging Operation (2) Dead electronic lower valve (Lift circuit) (3) Bucket lift control valve (4) Lift cylinders (5) Makeup valve (lift rod end) (6) Line relief valve (lift head end) (7) Bucket tilt control valve (8) Tilt cylinder (9) Line relief valve (tilt rod end) (10) Line relief valve (tilt head end) (18) Anti-drift valve (19) Accumulator (20) Flow from the charge circuit of the right drive pump (22) Margin relief valve (24) Pilot control solenoid (26) Implement pump (27) Hydraulic oil tank | |
The machine can perform a backdragging operation. The control levers must be returned to the HOLD position. During the backdragging operation, tilt cylinder (8) is held in the DUMP position and lift cylinders (4) are held in the LOWER position.
Dual setting relief valve (9) is used during backdragging operations in order to increase the maximum allowable pressure in the rod end of the tilt cylinder during backdragging operations.
The bucket is held in one position in order to drag the ground. the pressure in the rod end of lift cylinder (4) is used to increase the setting of dual setting relief valve (9). The bucket will stay in position until the ground causes enough force to overcome the setting of dual setting relief valve (9) .
When the relief valve setting is exceeded, oil from the tilt circuit is directed to the tank. The bucket moves in order to protect the components of the implement circuit.
Raise and Dump Operation
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| Illustration 7 | g01932121 |
Raise and Dump Operation (2) Dead electronic lower valve (Lift circuit) (3) Bucket lift control valve (4) Lift cylinders (5) Makeup valve (lift rod end) (6) Line relief valve (lift head end) (7) Bucket tilt control valve (8) Tilt cylinder (9) Line relief valve (tilt rod end) (10) Line relief valve (tilt head end) (18) Anti-drift valve (19) Accumulator (20) Flow from the charge circuit of the right drive pump (22) Margin relief valve (24) Pilot control solenoid (26) Implement pump (27) Hydraulic oil tank | |
When the implement control levers are simultaneously moved to the DUMP position and to the RAISE position, pilot oil is directed to the left side of tilt valve spool (7) and to the right side of lift valve spool (3). Tilt valve spool (7) shifts to the right and lift valve spool (3) shifts to the left.
Oil from implement pump (26) flows into the inlet passage. The oil is directed through the valve bank. Tilt cylinder (8) retracts and the bucket dumps. Lift cylinders (4) extend and the bucket raises.