An air supply unit for a pneumatic system is provided herein. The unit includes a compressor inlet for receiving compressed air in a supply mode. The unit further includes a consumption outlet for connecting at least one consumption circuit. The unit further includes an air processing unit connected to the compressor inlet for drying and filtering the compressed air and delivering dried compressed air at its outlet. The unit further includes a supply line extending from the outlet to the consumption outlet. The unit further includes a purge tank connected to the supply line. The purge tank is connected to the supply line through a throttle for pressure reduction of the purge air. In order to realize a short filling time, the purge tank is further connected to the supply line by a filling valve. The filling valve is open in the supply mode and blocking in the purge mode.

A hydraulic system in a work machine includes a hydraulic pump to supply pilot hydraulic oil. A work hydraulic actuator is to move a work device of the work machine. A control valve is to control the work hydraulic actuator based on a pilot pressure of the pilot hydraulic oil. A target pilot pressure of the pilot hydraulic oil is input through the work operation device to control, according to the target pilot pressure, the pilot pressure supplied from the hydraulic pump to the control valve. A pilot oil path connects the work operation device and the control valve to supply the pilot pressure to the control valve. A drain oil path is divided from the pilot oil path. A pressure adjustment valve is provided in the drain oil path to adjust the pilot pressure to be less than the target pilot pressure when a condition is satisfied.

A system and method configured to direct the braking energy from a high-pressure port at the motor side of a hydraulic circuit to emergency steering, braking, accumulator(s) charging, and/or various work functions. The system and method are also configured to return hydraulic fluid back to the same high-pressure port when the motor is running as a pump.

A refuse vehicle includes a chassis and a vehicle body. A variable displacement pump is positioned within the vehicle body and is configured to pump hydraulic fluid from a hydraulic fluid reservoir into a high pressure line of a hydraulic circuit. A lifting system on the vehicle includes at least one actuator in fluid communication with the variable displacement pump, which delivers pressurized hydraulic fluid from the hydraulic fluid reservoir to the actuator through the high pressure line to adjust a position of the actuator. A valve is positioned downstream of the variable displacement pump. In a first valve position, the valve restricts flow outward from the high pressure line. In a second valve position, the valve directs fluid from the high pressure line into a lower pressure line to reduce a hydraulic pressure within the high pressure line and adjust an output parameter of the variable displacement pump.

A system and method configured to direct the braking energy from a high-pressure port at the motor side of a hydraulic circuit to emergency steering, braking, accumulator(s) charging, and/or various work functions. The system and method are also configured to return hydraulic fluid back to the same high-pressure port when the motor is running as a pump.

Some of the present systems include a hydraulic power storage system having an accumulator configured to supply pressurized hydraulic fluid to a hydraulically actuated device to actuate the hydraulically actuated device and a drain in fluid communication with the accumulator and including a valve that is actuatable to drain hydraulic fluid from the hydraulic power storage system such that an internal pressure of the accumulator is reduced and a flow restrictor configured to reduce a flow rate of hydraulic fluid through the valve, a hydraulic pump configured to pressurize the accumulator, a pressure sensor configured to capture data indicative of the internal pressure of the accumulator, and a processor configured to actuate the hydraulic pump to increase the internal pressure of the accumulator if the internal pressure of the accumulator, as indicated in data captured by the pressure sensor, falls below a threshold pressure.

This disclosure includes systems and methods for actuating hydraulically-actuated devices.

A shovel includes a hydraulic pump, multiple hydraulic actuators, a center bypass oil passage supplied with hydraulic oil discharged from the hydraulic pump, multiple directional control valves, and a bleed-off valve. The directional control valves are arranged in tandem in the center bypass oil passage and configured to supply the hydraulic actuators with the hydraulic oil from the center bypass oil passage. At least a directional control valve other than the most downstream directional control valve in the center bypass oil passage among the directional control valves opens the center bypass oil passage. The bleed-off valve is connected to part of the center bypass oil passage upstream of at least one of the directional control valves.

A hydraulic drive system of a construction machine includes: an over-center pump connected to a turning motor; a regulator that adjusts tilting angle of the over-center pump; a main pump coupled to over-center pump; and a controller that controls the regulator such that when a turning deceleration operation is performed, the over-center pump's tilting angle decreases in accordance with decrease in a turning operation signal outputted from a turning operation device. The controller: when a pressure accumulation condition satisfied, switches a switching valve to pressure accumulation position to bring an accumulator into communication with a delivery line of the main pump; when a pressure release condition is satisfied, switches the switching valve to a pressure release position to bring accumulator into communication with a suction line of main pump; and when neither the pressure accumulation condition nor pressure release condition is satisfied, switches the switching valve to a neutral position.

A closed loop feedback circle drive system utilized onboard a motor grader includes an operator input device, a blade, and a multi-speed hydraulic motor having a motor output shaft. The motor output shaft is mechanically linked to blade such that motor output shaft rotation drives rotation of the blade about a blade rotation axis. A controller is operably coupled to the operator input device and to the multi-speed hydraulic motor. The controller is configured to: (i) receive blade rotation commands via the operator input device to rotate the blade about the rotation axis in a commanded manner; and (ii) control the multi-speed hydraulic motor to implement the blade rotation commands, while repeatedly adjusting the rotational speed of the motor output shaft to reduce variations in a rotational velocity of the blade due to changes in blade loading conditions occurring during motor grader operation.