Illustration 1 | g00718937 |
(1) Port (2) Port (3) Relief valve (4) Bolt (5) O-ring plug (6) Port |
Illustration 2 | g00719213 |
The counterbalance valve (tailgate) is located on the rear of the machine below the tailgate. |
The counterbalance valve (tailgate) is a relief valve. The counterbalance valve is subject to external pilot pressure from the piston side of the ejector cylinder. The counterbalance valve ensures that the tailgate opens only when the ejector cylinder is extending. The counterbalance valve also ensures that the tailgate closes only when the ejector cylinder is retracting.
Ejecting / Tailgate Opening
Oil from the piston sides of the tailgate cylinders flows to port (1). Pilot pressure from the ejector cylinder is transmitted to port (2). Pilot pressure from the piston side of the tailgate cylinders and from the piston side of the ejector cylinder acts on the counterbalance valve. Pressure within the piston side of the ejector cylinder rises when material contacts the tailgate. This opens the counterbalance valve which allows oil to flow from port (1) to port (6). Oil flows from port (6) to the tank and the tailgate opens.
Returning / Tailgate Closing
Pump oil flows to port (6). Flow from port (6) to port (1) is unrestricted. Oil flows from port (1) to the piston side of the tailgate cylinders. The tailgate closes.