A back-pressure control valve includes: a switching valve configured to open and close the connecting passage; and an emergency operation valve provided in the branch passage, the emergency operation valve being configured to open and close the branch passage by being operated manually. The emergency operation valve has a valve main body and a valve body. The valve body includes: the main body portion having the screw portion threaded into the valve main body; and the seat portion formed on the tip end of the main body portion, the seat portion being configured to open and close the branch passage by being seated on and separated from the valve seat provided in the accommodating hole.

Fast-acting and low-inertia actuators useable in various applications where a high force must be applied very quickly are disclosed. Power tools with detection systems configured to detect a dangerous condition between a person and a cutting tool are disclosed. In power tools, for example in a woodworking machine, a fast-acting and low-inertial actuator as disclosed herein can be used to retract a blade upon detection of a dangerous condition by a detection system. The actuator includes a charge of pressurized fluid and one or more electromagnets to selectively retain or release the pressurized fluid.

An exemplary valve bank and/or modular control valve having a valve body, a valve member movable in a fluid flow of the valve body to control flow of fluid, and an onboard electronic controller that is operably mounted to the valve bank or valve body. The onboard controller is operably connected to at least one actuator of the valve, which is configured to control movement of the valve member in response to commands from the onboard controller. The onboard controller may provide diagnostics, feedback and/or control of the control valve, such as via inputs from one or more sensors that may be included in the valve. The modular control valve may be used with conventional non-intelligent valve banks to thereby impart smart diagnostics and/or feedback into the valve bank in a plug-and-play manner. A communications interface may be provided in the control valve to interface and communicate with an upper-level PLC controller.

A valve arrangement has two main valves which are each preloaded by a spring device into a first switching position, and which can each be switched into a second switching position by means of an assigned pilot valve. The pilot medium required for switching is provided with a pilot pressure at a pilot connection of each pilot valve. The main valves are each equipped with a working valve section each of which are fluidically connected to one another. In addition, each main valve contains a monitoring valve section. The monitoring valve sections are designed to provide the venting of at least one pilot connection when the two main valves are in different switching positions. This allows a fluid-actuated actuator to be controlled in accordance with high safety standards.

Regeneration control is exercised and energy saving is realized even when an abnormality occurs to pressure sensors for hydraulic actuators. A work machine includes: a hydraulic pump (41b) that supplies a hydraulic fluid to a second hydraulic actuator (34); a regeneration circuit (47) that regenerates a return hydraulic fluid from a first hydraulic actuator (32) between the second hydraulic actuator (41b) and the hydraulic pump (41b); a discharge circuit (46) that discharges the return hydraulic fluid from the first hydraulic actuator (32) to a tank; a regeneration amount regulation device (45) that regulates a proportion of a flow rate of the return hydraulic fluid flowing to the regeneration circuit (47) and a flow rate of the return hydraulic fluid flowing to the discharge circuit (46); a controller (100) that controls the regeneration amount regulation device (45); a first operation amount sensor (53a) that detects an operation amount of the first operation device (51); and a first hydraulic actuator speed computing unit (111) that computes a speed of the first hydraulic actuator (32). The controller (111) controls the regeneration amount regulation device on the basis of the operation amount detected by the first operation amount sensor (53a) and the speed computed by the first hydraulic actuator speed computing unit (111).

A method includes receiving pump cycle location data associated with a fluid power system. The fluid power system includes a plurality of pumps (including at least a first pump, a second pump, and a third pump). Based on the pump cycle location data having a first value, the method includes activating the first pump as a primary pump. Based on the pump cycle having a second value, the method includes activating the second pump as the primary pump. The method also includes activating the third pump as a secondary pump when the fluid power system is in a multiple-pump operating mode.

A method for preventing control-induced oscillations in a valve with a pneumatic actuator and position control with an integrating component, including the following steps: Checking whether oscillations of the valve member occur by counting the zero crossings or extreme values of the control difference. If oscillations were detected, it is checked whether they result from oscillations of the set point. If not, the dead zone is increased and/or the gain parameter is decreased. If no oscillations were detected, it is checked whether wear in the drive has exceeded a predetermined measure. If so, the dead zone is decreased and/or the gain parameter is increased. In this way, oscillations caused by the I-component of the control can be detected and stopped. Further changes to the parameters are only made when friction is expected to have decreased due to wear.

A method includes receiving pump cycle location data associated with a fluid power system. The fluid power system includes a plurality of pumps (including at least a first pump, a second pump, and a third pump). Based on the pump cycle location data having a first value, the method includes activating the first pump as a primary pump. Based on the pump cycle having a second value, the method includes activating the second pump as the primary pump. The method also includes activating the third pump as a secondary pump when the fluid power system is in a multiple-pump operating mode.

This invention includes a hydraulic pump (9), a working implement (107) having a lift cylinder (13) driven by a hydraulic fluid supplied from the hydraulic pump (9), an operating device (104) for operating the working implement (107), a traveling motor (7) for driving wheels, and a main controller (100). When the lift cylinder (13) fails to operate despite an extending instruction being imparted to the lift cylinder (13) via the operating device (104), the main controller (100) reduces a limit value for an increase rate of a torque required in the traveling motor (7) to a value smaller than that applied when the lift cylinder (13) operates. With this configuration, occurrence of wheel slip during lifting of an object to be carried can be reduced.

Disclosed are a novel rotation control system and method for an excavator. The novel rotation control system comprises a controller, an electrical control handle, an instrument, a rotating motor, a rotating valve trim, a main pump, a first electromagnetic valve, a second electromagnetic valve, a first pilot pressure sensor, a second pilot pressure sensor, an overflow valve and a one-way valve, and further comprises a rotation sensor used for detecting whether an excavator is rotating, a regulator used for controlling the displacement of the main pump, and a temperature sensor used for monitoring the temperature of hydraulic oil in real time.