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| Illustration 1 | g06227883 |
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Typical example (1) Port (2) Port (3) Tailgate counterbalance valve (4) Port (5) Check valve | |
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| Illustration 2 | g06270248 |
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View of the tailgate counterbalance valve (1) | |
The tailgate counterbalance valve (1) is a relief valve. The counterbalance valve ensures that the tailgate opens only when the hoist control valve is moved to the EJECT position.
Eject/Tailgate Lower
When the hoist control is in the EJECT position, oil is directed from the ejector sequence valve to port (1) of counterbalance valve (3). When, the oil in port (1) reaches a preset pressure counterbalance valve (3) opens. Oil flows from the rod end of the tailgate cylinder through port (2) to port (4) and returns to the brake cooling circuit. The tailgate cylinders extend and the tailgate lowers.
Retract/Tailgate Raise
When the hoist control is in the RETRACT position, oil is directed from the ejector sequence valve to port (4) of counterbalance valve (3). Oil flows from port (4) through check valve (5) to port (2) of counterbalance valve (3). Oil from port (2) flows to the rod end of the tailgate cylinders. When, the tailgate cylinders are fully retracted check valve (5) closes. This, prevents the reverse flow of oil through counterbalance valve (3) to hold the tailgate closed.