Abstract: A valve device switching between an open position and a close position, the open position allowing passage of oil through a gap between two ports in a spool bore from a small-diameter portion of a spool via a notch formed in a large-diameter portion of the spool, the close position blocking passage of oil through the gap between the two ports by the large-diameter portion, wherein the notch of the large-diameter portion has an inner bottom face at a portion located on a center side of the spool and is open to an outer peripheral space of the small-diameter portion and an outer peripheral surface of the large-diameter portion, and is formed such that an opening width of an opening at the outer peripheral surface is larger than a width of the inner bottom face.

Abstract: A valve device switching between an open position and a close position, the open position allowing passage of oil through a gap between two ports in a spool bore from a small-diameter portion of a spool via a notch formed in a large-diameter portion of the spool, the close position blocking passage of oil through the gap between the two ports by the large-diameter portion, wherein the notch of the large-diameter portion has an inner bottom face at a portion located on a center side of the spool and is open to an outer peripheral space of the small-diameter portion and an outer peripheral surface of the large-diameter portion, and is formed such that an opening width of an opening at the outer peripheral surface is larger than a width of the inner bottom face.

Abstract: A fan drive system for driving an engine cooling fan mounted in a working machine is described. The fan drive system includes a variable displacement pump that supplies oil to an actuator and is also used as a hydraulic pump for the hydraulic motor that drives the cooling fan. A pump displacement of a variable displacement pump can be controlled in accordance with the load of the working machine, and when a load is not generated in the working machine, the pump displacement of the variable displacement pump can be controlled in accordance with a load pressure of a hydraulic motor which drives a cooling fan. Examples of such working machines include a forklift, a skid steer loader (SSL) and a crawler dump.

Abstract: A pressurized hydraulic fluid supply apparatus capable of merging or separating a plurality of hydraulic pump lines according to the driving states of a plurality of actuators. The pressurized hydraulic fluid supply apparatus has a merge/separation valve 40 that merges or separates the hydraulic fluids delivered under pressure by the first hydraulic pump 1 and the second hydraulic pump 11. The merge/separation valve 40 is set to a flow separation state upon driving of the second hydraulic actuator 16 and is preferentially shifted to a flow merging state when the third hydraulic actuator 21 is driven. Hence, even when a manually driven operation valve is used, the merge/separation valve 40 is automatically switched between the flow separation state and the flow merging state according to the operation of the operation valve. This apparatus prevents an unintended flow rate difference between the first and second actuators from being produced upon driving of the third actuator.