A good friend just bought a Clark 667 Ranger with grapple that has a hydraulic tank below the fuel tank that is inline with the pincher. We presumed that it is some type of accumulator to hold the logs tight when you have completed pinching the log to keep it from slipping. This was disconnected when he bought it (bypassed) when we tried to reconnect it the pincher (Tong) to the tank it would pinch tight but will not release. if we by pass the accumulator the pincers work fine but will not hold tension on the log, seem to leak off. We can find no information on this tank or it's function or how it works, the tank is inline with the pincher and the control valve with another valve in between the two I can only assume that it is some kind of check valve to hold the pressure on the accumulator and log. Does any of you gentlemen have any expertize in this area or access to illustrations of this setup?? Any help would be appreciated. Thanks
It is probably a nitrogen charged accumulator. Since hydraulic oil is incompressible, an accumulator has to have a spring piston or a gas charge or something to store the energy.
Have a look at that extra valve, any other lines going to it, or places where other lines could connect? Try to put up some pictures if you can, might be a lock valve, or possibly just a restrictor check.