A hydraulic unit is provided with: a manifold which forms a hydraulic circuit; a tank which is joined to the manifold; and a hydraulic pump which suctions hydraulic fluid in the tank and supplies the hydraulic fluid to the manifold, wherein the base end portion of a suction strainer is fitted into the hydraulic pump, and the suction strainer has such a shape that the base end portion of the suction strainer is not separated from the hydraulic pump in a state where the leading end portion of the suction strainer is in contact with the tank and an opening through which the hydraulic fluid is introduced from the tank is provided at the leading end portion.

A flow rate controller and a drive device are provided with a cylinder flow passage connected to an air cylinder; a main flow passage for supplying air to and discharging air from the air cylinder; an auxiliary flow passage that has a first throttle valve and through which exhaust air discharged from the air cylinder passes with a smaller flow rate than that of the main flow passage; a switch valve that switches between a first position in which the cylinder flow passage communicates with the main flow passage and a second position in which the cylinder flow passage communicates with the auxiliary flow passage; and a pilot air adjustment part that guides a portion of the exhaust air from the air cylinder as pilot air to the switch valve.

A tilting system for a suspended cab of a work vehicle includes a hydraulic cylinder coupled to a chassis of the work vehicle at a first end and the suspended cab at a second end. Further, the hydraulic cylinder is configured to extend to drive the suspended cab to rotate from a lowered position to a raised position. In addition, the hydraulic cylinder is configured to be substantially horizontal while the suspended cab is in the lowered position.

A control device for a fluid pressure actuator includes a first valve controlling a flow of working oil supplied to or discharged from a hydraulic cylinder, a regulation determining portion determining whether to increase or decrease an energization amount to the first valve on the basis of a position deviation between an actual position and a target position of the hydraulic cylinder, a first proportional gain output portion deciding a command current value to be applied to the first valve on the basis of the position deviation, and an offset current output portion setting an offset current value to be applied to the first valve on the basis of a judgment result of the regulation determining portion. The offset current output portion sets a first current value as the offset current value in a valve closing process, and sets a second current value greater than the first current value as the offset current value in a valve opening process.

A control valve device includes a valve block that switches the flowing direction of a working fluid supplied to and discharged from a boom cylinder and an arm cylinder (actuators). The valve block includes an actuator port connected to the boom cylinder, and a supply port, a discharge port, and a regeneration port communicating with the actuator port. A supply valve is provided between the actuator port and the supply port, and a discharge valve is provided between the actuator port and the discharge port.

A method of controlling a plurality of downhole tools in a wellbore, using first and second codes transmitted by hydraulic line to first address and then actuate the desired tool. A dedicated line is provided for terminating all actuated tools.

A pneumatic manifold with internal and external porting is machined in a specific sequence for pressurized and exhausting air control. Electro-pneumatic valves and or blocking plates are fastened and sealed to the positions of exterior porting. The electro-pneumatic valves complete the pneumatic circuit already machined in the manifold. Electro-pneumatic valves can be added or removed depending on the required functions. Other exterior ports on the manifold allow for but are not limited to connection of a pressure transducer, exterior pilot feeds, individual open/close speed controls, individual secondary slow down speed controls for open and close. The manifold allows the mounting of three electro-pneumatic valves wherein each valve controls a certain specific sequential function. When used with a compatible means of electronic control, the manifold can replace most pneumatic control devices driving a pneumatic actuator for the purpose of moving an access mechanism, such as a garage door.

A hydraulic control device of a forklift truck includes a first hydraulic cylinder, a first instruction member, a second hydraulic cylinder, a second instruction member, a hydraulic pump, an electric motor, a first passage which has a drain passage, a lowering control valve that controls flow of hydraulic oil, a flow rate control valve, and a controller. When a lowering operation of forks and an operation of a hydraulically-operated unit are performed simultaneously, when a required rotation speed of the hydraulic pump that is required for operating the hydraulically-operated unit at an instruction speed based on an operation of the second instruction member is a specified rotation speed or lower, the controller controls an instruction rotation speed of the electric motor so as to operate the hydraulic pump at the required rotation speed to thereby restrict the operation of the hydraulic pump.

In a hydraulic driving system for construction machines, when track motors 3f and 3g are operated and the delivery pressure of a main pump 2 increases to a second value PS2 of the set pressure of a main relief valve 14, the set pressure of a signal pressure relief valve 16 increases from a third value PA1 to a fourth value PA2, which is smaller than the second value PS2 of the set pressure of the main relief valve 14, the difference between the second value PS2 and the fourth value PA2 being smaller than the target LS differential pressure. With such a structure, even if one of actuators reaches the stroke end and the delivery pressure of the hydraulic pump rises to the set pressure of the main relief valve, the other actuators do not stop, and further when the main relief valve is configured to increase the set pressure during operation of a specific actuator, the load pressure of the specific actuator does not increase to the increased set pressure of the main relief valve.

A nose-wheel steering system is provided. The nose-wheel steering system includes a hydraulic motor including a drive shaft configured to rotate about a first axis; and a hydraulic motor start assist mechanism coupled to the hydraulic motor and configured to provide a temporary boost of hydraulic fluid pressure supplied to the hydraulic motor.