Abstract: An hydraulic steering device for a crawler-mounted vehicle, in which a couple of pressure-regulating steering valves controls the rotation direction and speed of two respective rolling trains of the vehicle, is described. Each of the valves is provided with an end chamber having a piston sliding therein in response to a control pressure depending on the pilot pressure regulated by the other steering valve, and each piston is designed to shift respective shouldering means for respective contrast springs of respective shuttles provided on the valves in such a manner that both the rolling trains are stopped whenever both of the valves are activated simultaneously.

Abstract: A linkage system for a loader vehicle of the type comprising a pair of parallel lift arms having a first upper end pivotally connected to upper end portions of a vertical bracket member secured to the frame of the vehicle and a second lower end pivoted to an associated lower back portion of a bucket, a pair of bellcrank levers, the central portions of which are pivotally connected to corresponding upper end portions of the lift arms, a pair of connecting links having one or a first end pivotally connected to a lower end of the bellcrank levers and its other end pivotally connected to associated intermediate portions of the bracket members secured to the frame and a pair of bucket cylinders for control of rotation of the bucket about its lower end portion, having a head end pivotally connected to a corresponding upper end of the bellcrank levers and a rod end pivotally connected to an associated upper back end portion of the bucket.

Abstract: A manually-operable hydraulic control device of the hydraulic pressure liquid directional control type, with hydraulic position-retention, particularly for regulating the flow of pressurized fluid supplied to the power jack of a component or implement of an earth moving machine, comprises a pair of valves and a control lever having a central neutral position and two respective extreme operative positions for controlling the said valves. The device is provided with hydraulic means for retaining the control lever in at least one of the said extreme operative positions.