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| Illustration 1 | g00470936 |
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| Illustration 2 | g00466721 |
(1) Main control valve (2) Port (drain) (3) Ball valve (4) Pipe (5) Pump oil line for attachment (6) Line for front pump oil supply (7) Port (attachment control valve) (8) Pump oil line for attachment (9) Tee (10) Relief valve (two places) (11) Port (attachment control valve) (12) Check valve (A) CLOSED position (B) OPEN position | |
One Pump Flow and Two Pump Flow
Two Pump Flow
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| Illustration 3 | g00466722 |
(3) Ball valve (12) Check valve (A) CLOSED position (B) OPEN position | |
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| Illustration 4 | g00466723 |
Check valve (12) Check valve (13) Outlet (14) Spring (15) Valve (16) Inlet | |
Front pump oil is supplied to tee (9) which is attached to the main pump. With ball valve (3) in the OPEN position (B) , the pump oil flows to check valve (12) .
Valve (15) shifts to the left when the load increases for the attachment. When the load increases, the pressure decreases and the check valve opens. This allows pump oil to flow through check valve (12) to the attachment control valve. The attachment circuit now operates with front pump oil and rear pump oil.
Valve (15) shifts to the right when the load decreases for the attachment. When the load decreases, the pressure increases and the check valve closes. The attachment operates with only front pump oil.
One Pump Flow
When one pump flow is required, ball valve (3) is in the CLOSED position (A) . In this position, the flow of rear pump oil to check valve (12) is blocked. The attachment gets pump oil only from the front pump.
Single Action and Double Action
Single Action Hydraulic Attachment
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| Illustration 5 | g00466717 |
(17) Boom (18) Check and relief valve (19) Line (line to port (22) ) (20) Line (line to port (24) ) | |
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| Illustration 6 | g00466747 |
Check and relief valve (18) Check and relief valve (21) Relief valve (22) Port (23) Check valve (24) Port | |
When the control pedal is depressed, pump oil flows from port (11) of the attachment control valve to pipe (4) . The pump oil flows to the attachment from the pipe through line (5) . Supply oil that flows to the attachment goes through line (5) . Check valve (18) is placed in the circuit in order to prevent pressure buildup.
Relief valve (21) senses the oil pressure in port (22) . Relief valve (21) is set to open at 17700 ± 500 kPa (2567 ± 72 psi). The relief valve controls the operating pressure of attachments.
Note: The pressure setting must be reset to the proper specification for the attachment that is being used.
When the relief valve opens, oil flows to the top of check valve (23) . When the oil pressure is greater than the oil pressure in port (24) and the force of the spring, the check valve opens. The oil then goes to the drain.
Relief valve (21) is set lower than line relief valves (10) on the attachment control valve. Line relief valves (10) do not affect the attachment.
The return oil from the attachment flows through line (8) to the hydraulic tank through the attachment control valve.
Double Action Hydraulic Attachment
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| Illustration 7 | g00466718 |
(17) Boom (25) Ball valve (selector valve for single action and double action) (26) Line (line to port (31) ) (27) Line (line to ball valve) (28) Line (line to port (32) ) (29) Line (line to attachment) | |
When the ball valves are set to the DOUBLE ACTION position (C) , pump oil can flow in two directions to the attachment.
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| Illustration 8 | g00537646 |
Ball valve (25) Ball valve (C) DOUBLE ACTION position (D) SINGLE ACTION position | |
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| Illustration 9 | g00466719 |
(25) Ball valve (selector valve for single action and double action) (27) Line (line to ball valve) (29) Line (line to attachment) (30) Relief valve (31) Port (32) Port | |
When pump oil flows from port (11) of the attachment control valve, the oil goes to pipe (4) . The pump oil then flows through line (5) to the attachment. With ball valve (25) in the DOUBLE ACTION position (C) , pump oil is directed around ball valve (25) to the attachment. When the control pedal is depressed in one direction, pump oil is provided to one side of the attachment. When the control pedal is depressed in the other direction, supply oil is provided to the other side of the attachment. This is the double action of the attachment. Relief valve (30) provides pressure relief to either side of the attachment.
With ball valve (25) in the SINGLE ACTION position (D) , single action is obtained.
The two line relief valves (10) prevent pressure buildup in the circuit for double action. The relief valves are set to 36260 kPa (5259 psi) at the factory. The pressure setting must be reset to the proper specification for the attachment that is being used.