A cooling flow circuit is provided and includes a main line having first and second sections ported to piston extend and return sides of the gas turbine engine actuator, respectively, an orifice disposed along the main line between the first and second sections, a bypass line and a bypass valve. The bypass line is fluidly coupled to the first and second sections at opposite ends thereof, respectively. The bypass valve is disposed along the bypass line between the opposite ends thereof. The bypass valve has a variable flow area which is responsive to a pressure differential between the first and second sections.

A cooling flow circuit is provided and includes a main line having first and second sections ported to piston extend and return sides of the gas turbine engine actuator, respectively, an orifice disposed along the main line between the first and second sections, a bypass line and a bypass valve. The bypass line is fluidly coupled to the first and second sections at opposite ends thereof, respectively. The bypass valve is disposed along the bypass line between the opposite ends thereof. The bypass valve has a variable flow area which is responsive to a pressure differential between the first and second sections.

An actuating drive for a control valve contains a working cylinder which has a piston and a piston rod and forms an actuator for the control valve. The piston bounds a first pressure space and a second pressure space to displace the piston counter to the force of a spring by applying pressure to the first pressure space via a working medium. A working medium circuit is connected to the working cylinder at first and second pressure connections to introduce and evacuate the working medium into/from the first and second pressure spaces. The working medium circuit has a working medium pump connected to convey the working fluid, at a pressure side, to the first pressure connection, and at a suction side, to the second pressure connection. The first pressure space is permanently connected, so as to convey working fluid, to the second pressure space via a bypass line.

A hydraulic system (e.g., of an aircraft or other vehicle) includes a pump, a pressure line coupled to the pump and configured to distribute pressurized hydraulic fluid, and a return line configured to return hydraulic fluid to a reservoir. The hydraulic system also includes an auxiliary leakage valve coupled to the pressure line, to the return line, and to an actuator. The auxiliary leakage valve is configured to receive a control signal and, based on the control signal, selectively open a restricted fluid path. The restricted fluid path couples the pressure line to the return line to allow a restricted amount of the hydraulic fluid to flow from the pressure line to the return line.

A system and method include a hydraulic system onboard an aircraft, a first temperature sensor, a second temperature sensor, and a controller. The first temperature sensor measures a first temperature of hydraulic fluid upstream of an inlet of a pump of the hydraulic system. The second temperature sensor measures a second temperature of the hydraulic fluid within a cooling flow stream downstream of an outlet of the pump. The controller determines a value of a temperature rise of the hydraulic fluid across the pump as a difference between the first temperature and the second temperature, and obtains an expected range for the temperature rise across the pump based on a speed of the pump. In response to the value of the temperature rise being outside of the expected range, the controller generates a maintenance message for communication off-board the aircraft, indicating the pump is degraded.

An apparatus and method of cooling an engine exhaust generated by an engine of a work machine having a hydraulically operated implement. The work machine includes an emission control system and a cooling system having an oil cooling system configured to cool an oil of a hydraulic system and an engine cooling system configured to cool an engine coolant circulating through the engine. An exhaust pipe, coupled to the emission control system and configured to direct engine exhaust, includes an outlet disposed in a space located between an oil cooler of the oil cooling system and a radiator of the engine cooling system. An air displacement device is configured to draw air into and away from the oil cooler and the radiator and to draw the exhaust from the exhaust pipe. Exhaust from the exhaust pipe is drawn past the oil cooler and the radiator to cool the exhaust.

An apparatus and method of cooling an engine exhaust generated by an engine of a work machine having a hydraulically operated implement. The work machine includes an emission control system and a cooling system having an oil cooling system configured to cool an oil of a hydraulic system and an engine cooling system configured to cool an engine coolant circulating through the engine. An exhaust pipe, coupled to the emission control system and configured to direct engine exhaust, includes an outlet disposed in a space located between an oil cooler of the oil cooling system and a radiator of the engine cooling system. An air displacement device is configured to draw air into and away from the oil cooler and the radiator and to draw the exhaust from the exhaust pipe. Exhaust from the exhaust pipe is drawn past the oil cooler and the radiator to cool the exhaust.

A hydraulic system of a work machine includes a first oil path which is connected to a hydraulic pump and though which hydraulic oil is to flow from the hydraulic pump. An operation valve is connected to the first oil path. An operation lever is to control the operation valve to control pressure of the hydraulic oil in accordance with an operation of the operation member. A hydraulic instrument is to be actuated by the hydraulic oil output from the operation valve. A second oil path connects the operation valve and the hydraulic instrument. The hydraulic oil in the second oil path is discharged through a discharge oil path. An actuation valve is provided in the discharge oil path. An actuation valve controller is to control the actuation valve to be opened and closed according to a temperature of hydraulic oil detected by a first sensor.

An apparatus and method of cooling an engine exhaust generated by an engine of a work machine having a hydraulically operated implement. The work machine includes an emission control system and a cooling system having an oil cooling system configured to cool an oil of a hydraulic system and an engine cooling system configured to cool an engine coolant circulating through the engine. An exhaust pipe, coupled to the emission control system and configured to direct engine exhaust, includes an outlet disposed in a space located between an oil cooler of the oil cooling system and a radiator of the engine cooling system. An air displacement device is configured to draw air into and away from the oil cooler and the radiator and to draw the exhaust from the exhaust pipe. Exhaust from the exhaust pipe is drawn past the oil cooler and the radiator to cool the exhaust.

To provide a construction machine including a novel preheating unit that can efficiently preheat entire circulation channel where fluid flows, and a preheating method of the construction machine. A bypass channel is arranged in a circulation channel through which the fluid is circulated, this bypass channel is provided with the preheating unit that is formed of a heater and a bypass pump. According to such configuration, even in a state circulation of the fluid may stop in the circulation channel, the fluid can be heated while the fluid is circulated through the bypass channel, and therefore the entire circulation channel can be efficiently preheated. Moreover, since retrofitting to the existing circulation channel is possible, sound versatility can be exerted.