Crop-loading-responsive fluid supply circuit in bale density control system

Claim 1

In a baler of the type wherein a reciprocating plunger progressively forms a bale by incrementally forcing the same through the restricted orifice of a baling chamber as a loader successively inserts new charges of material between the retracted plunger and the bale in timed relationship to reciprocation of the plunger, said orifice being at least partially defined by structure that is shiftable laterally with respect to the path of bale travel through said chamber for the purpose of enlarging or restricting said orifice, said structure having a fluid-pressure device coupled therewith for applying a holding force against movement of the structure in a direction to enlarge the orifice, said loader having control means associated therewith for temporarily deactivating the loader without interrupting reciprocation of the plunger, the improvement comprising: a fluid-pressure circuit connected with said device for pressurizing the same to effect said holding force, said circuit including a fluid pump and a check valve between said pump and said device operable when closed to prevent fluid flow into said device from the pump for further pressurization of the device, said pump being operable during each compaction stroke of the plunger, if the pressure in said circuit on the pump side of said check valve exceeds the pressure in said circuit on the device side of said valve whereby to open said check valve, to add a slug of fluid to said device for further pressurization thereof, said circuit being responsive to pressure therein beyond a certain predetermined level to depressurize said device by an amount which reduces said holding force, said circuit further including a control valve on the pump side of said check valve operable when closed to preclude said addition of a slug of oil to the device by the pump and operable when open to permit said slug addition; and valve operating means responsive to operation of said loader for closing said control valve upon said deactivation of the loader.