Abstract: A pressure compensation unit includes: a control valve controlling hydraulic fluid supply and discharge to and from an actuator, the control valve including a pump port, a pair of relay and supply/discharge ports, and a tank port; a pressure compensation valve connected to the relay ports by an upstream and downstream-side relay lines, the pressure compensation valve moving in accordance with a pressure difference between upstream-side relay line and signal pressure; a load pressure detection line branching from the downstream-side relay line; a relief line connected to the downstream-side relay line and having a relief valve; and a switching valve leading: a maximum load pressure to the pressure compensation valve as the signal pressure when the hydraulic fluid does not flow through the relief line; and a pump pressure to the pressure compensation valve as the signal pressure when the hydraulic fluid flows through the relief line.

Abstract: A pressure compensation unit includes: a control valve controlling hydraulic fluid supply and discharge to and from an actuator, the control valve including a pump port, a pair of relay and supply/discharge ports, and a tank port; a pressure compensation valve connected to the relay ports by an upstream and downstream-side relay lines, the pressure compensation valve moving in accordance with a pressure difference between upstream-side relay line and signal pressure; a load pressure detection line branching from the downstream-side relay line; a relief line connected to the downstream-side relay line and having a relief valve; and a switching valve leading: a maximum load pressure to the pressure compensation valve as the signal pressure when the hydraulic fluid does not flow through the relief line; and a pump pressure to the pressure compensation valve as the signal pressure when the hydraulic fluid flows through the relief line.

Abstract: A stack valve 1 includes an ascending dividing valve 14 which is provide on an ascending junction path 23 and controls the flow rate of a pressure fluid supplied to a head-side chamber 4a of a bucket cylinder 4, an ascending branched path 24 which is branched from the ascending junction path 23 and connected to an unloading path 21, and an ascending cancellation switching valve 19 which is provided on the ascending branched path 24 to close or open the ascending branched path 24. The ascending dividing valve 14 and the ascending cancellation switching valve 19 are provide in the same dividing section 83.

Abstract: A stack valve 1 includes an ascending dividing valve 14 which is provide on an ascending junction path 23 and controls the flow rate of a pressure fluid supplied to a head-side chamber 4a of a bucket cylinder 4, an ascending branched path 24 which is branched from the ascending junction path 23 and connected to an unloading path 21, and an ascending cancellation switching valve 19 which is provided on the ascending branched path 24 to close or open the ascending branched path 24. The ascending dividing valve 14 and the ascending cancellation switching valve 19 are provide in the same dividing section 83.

Abstract: An arm direction changeover valve (11) is provided in an arm block (20). A first pilot check valve (18) is provided in a first block (21). A second pilot check valve (19) is provided in a second block (22). The three blocks, i.e., the arm block (20), the first block (21), and the second block (22) are arranged side by side. The first block (21) and the second block (22) are arranged to be contiguous to each other. Accordingly, an increase in size can be prevented even if a float mechanism and a multi-direction changeover valve are formed integrally with each other.

Abstract: An arm direction changeover valve (11) is provided in an arm block (20). A first pilot check valve (18) is provided in a first block (21). A second pilot check valve (19) is provided in a second block (22). The three blocks, i.e., the arm block (20), the first block (21), and the second block (22) are arranged side by side. The first block (21) and the second block (22) are arranged to be contiguous to each other. Accordingly, an increase in size can be prevented even if a float mechanism and a multi-direction changeover valve are formed integrally with each other.

Abstract: A bellows-form boot for universal joint which is formed integrally of a le-diameter cylindrical portion and a small-diameter cylindrical portion at both ends, the former being adapted to be fitted to a joint case housing therein the universal joint and the latter to a driving shaft, a central annular bellows portion having ridge portions whose diameters are tapered down toward the small-diameter portion, and a bracing boss portion extending between the large-diameter portion and the bellows portion. The boss portion has a wall thickness of 2 to 3 times the average wall thickness of the bellows portion and is profiled so that the inner face thereof may abuttingly contact with the edge face of the joint case and the outer face thereof is flush with the outer face of the bellows portion in the mutual joining area.

Abstract: A dust boot for a universal joint covering two joint elements having largely curved corner portions in the outer peripheral surface thereof near their joint portion, comprises a resilient annular covering portion for covering the joint portion of the universal joint and two annular end portions which are integrally formed with the covering portion in axially both ends thereof. The annular end portions are mounted on the two joint elements near their joint portion. Since the area of an open end of the dust boot mounted on the joint element having largely curved corner portions is made smaller than the cross sectional area of the outer peripheral surface of the joint element, specifically only the curvature of the open end of the dust boot corresponding to the largely curved corner portions of the joint element is made smaller than that of the corner portions of the joint element, the dust boot can be closely mounted on the joint element with excellent sealing effect.

Abstract: A tripod type constant velocity universal joint for interconnecting two shafts to permit transmission of a driving force in a vehicle such as a motor car. In said tripod type constant velocity universal joint, a trunnion portion of the tripod shafts is urged against and supported by a tulip portion of a second shaft by a tripod spring, the spherical head of a mushroom-shaped member provided in the mounting hole of said trunnion portion is kept in contact with a recess in said tulip portion by the biasing force of a compression spring, and further, said mushroom-shaped member or said trunnion portion of the tripod shafts is formed to provide a spherically curved surface or a conical surface incorporating a straight line, in which the distance from the center of the joint is increased as a point on the external configuration leaves the center toward the outer periphery.