Abstract: The present invention relates to a device for controlling two fluid-controlled drive members, one of which is double-acting, wherein a communication conduit connects the supply conduits of said double-acting drive member, a non-return valve being disposed in said communication conduit and allowing the passage of the fluid solely from the small chamber towards the large chamber of said double-acting drive member, while another conduit is adapted to connect the large chamber of the double-acting drive member to the chamber of the second drive member. The result of the invention is the elimination of lift of a hydraulic loading shovel when digging.

Abstract: An earth moving machine having a boom, a dipperstick, and a bucket all mounted for pivotal movement one with respect to the other, a double acting cylinder for each of the boom, the dipperstick, and the bucket, respectively, for controlling the pivotal movement of the bucket, for raising and lowering the boom, and for extended and retracting the dipperstick.

Abstract: The invention relates to a hydraulic loader comprising a boom, a balance beam and a bucket for loading material, boom jacks and balance beam jacks being coupled between the frame and the boom and between the boom and the balance beam. A secondary jack is also coupled between the frame and the boom and comprises an active chamber, while a first conduit connects this active chamber to the extension chamber of the balance beam jack and a first cut-off valve is disposed in this first conduit, establishing, in its first position, communication of the two sections of the first conduit which are connected thereto, isolating, on the contrary, in its second position, these two sections. One application of the invention is the production of a powerful and efficient loader.

Abstract: A control system for stopping a hydraulic motor in a predetermined position comprises a valve connected in parallel across the motor, the valve having a closed position and an open position in which flow is via a throttle orifice. When the motor is being driven normally the valve is closed. When the main control regulator for the motor is moved to stop the motor, the valve is automatically opened to allow limited fluid flow through the motor during a slowing down phase. A detector senses when the motor is a predetermined distance from its desired stopping position, and moves the valve to its closed position. Overload valves are provided to prevent overpressures.

Abstract: A fluid supply circuit for supplying three motors includes means for sequentially connecting two of the motors to the supply conduit of the third motor as the pressure in the supply conduit rises through first and second threshold levels. The circuit includes a manual override for suppressing the automatic sequential action. The circuit is applied to the control of the booms and bucket of a hydraulic excavator, and provides for semi-automatic digging.