Abstract: A hydraulic valve assembly for use with a fluid motor has a control device, e.g., a valve spool, mounted for movement between a neutral position for motor disabling and an output position for motor operation. The improvement comprises a locking surface on the device and a lock member engaging the surface when the device is in the neutral position. Such lock member prevents movement of the device to the output position. The valve assembly may have two control devices, each having a locking surface. The lock member engages (or disengages from) such surfaces simultaneously. Means for manual and remote shifting of the locking member are also disclosed. The new assembly is particularly useful in mobile machines having hydraulically-operated equipment, e.g., a loader bucket, which is raised above ground.

Abstract: A hydraulic system suited for use with a backhoe apparatus and which is configured to automatically direct a priority flow of actuating fluid from an actuating fluid source to hydraulic motors used to swing the backhoe apparatus into a desired swing position independently of other backhoe operations and the corresponding loads thereof. The hydraulic system of the present invention includes a priority valve which is connected to the fluid source and has priority and secondary hydraulic circuitry extending therefrom. The priority valve is positioned under the influence of fluid pressure differentials applied against it. In response to operator desires to swing the backhoe apparatus from one position to another, the priority valve automatically directs a dedicated flow of actuating fluid through the priority circuit to the swing motors used to swing the backhoe apparatus into the desired swing position.