Systems and methods for electrohydraulic valve calibration are provided. In one aspect, a calibration circuit includes a calibration conduit isolated from a supply conduit, a first calibration orifice configured to provide fluid communication between the calibration conduit and a fluid source, and a second calibration orifice arranged in series with the first calibration orifice. The second calibration orifice is on a spool of a electrohydraulic control valve and is configured to selectively provide fluid communication between the calibration conduit and a low pressure source. The calibration circuit further includes a pressure sensor configured to measure a pressure in the calibration conduit between the first calibration orifice and the second calibration orifice. The second calibration orifice is isolated from the at least one workport of the electrohydraulic control valve.

A main flow path that introduces high-pressure air to an air cylinder, or discharges exhaust air therefrom, includes a sub flow path provided alongside the main flow path; an exhaust flow rate adjustment unit that suppresses the operation speed of the air cylinder by adjusting the flow rate of the exhaust air flowing through the sub flow path; and a switching valve that is connected between the air cylinder, the main flow path and the sub flow path, and that connects the main flow path and the sub flow path to the air cylinder in a switching manner. The switching valve is constituted by a spool valve.

A hydraulic drive system includes a swing directional control valve 81 and a third boom directional control valve 82 that are connected to a third hydraulic pump 33. Furthermore, the hydraulic drive system includes: a second auxiliary directional control valve 84 that is connected to the third hydraulic pump 33, and is connectable with a second special hydraulic actuator 64 for driving special attachments; and a first selector valve 96 that is connected to the third hydraulic pump 33 upstream of the second auxiliary directional control valve 84, and is connectable with an additional hydraulic pump 97. The first selector valve 96 switches the hydraulic fluid source of the second special hydraulic actuator 64 connected to the second auxiliary directional control valve 84 at least between the third hydraulic pump 33 and the additional hydraulic pump 97. Operability for combined operation of a special attachment can be improved in the hydraulic drive system equipped in advance with an auxiliary directional control valve that is connectable with an additional hydraulic actuator for driving the special attachment.

A hydraulic system includes a hydraulic circuit, a heater, a temperature sensor, and a controller. The hydraulic circuit includes a reservoir configured to store hydraulic fluid, a pump coupled to the reservoir, a driver positioned to drive the pump to pump the hydraulic fluid from the reservoir and throughout the hydraulic circuit, and an actuator positioned to selectively receive the hydraulic fluid from the pump to operate a controllable machine component. The driver is independent of a prime mover of the machine. The heater is positioned to facilitate selectively heating the hydraulic fluid. The temperature sensor is positioned to acquire temperature data indicative of a temperature of the hydraulic fluid. The controller is configured to monitor the temperature of the hydraulic fluid and selectively activate at least one of the heater or the pump to thermally regulate the hydraulic fluid to maintain the hydraulic fluid within a target temperature range.

A method is provided for the simultaneous detection, localization, and quantification of leaks and obstructions in a gas network under pressure or vacuum. The gas network includes: one or more sources of compressed gas or vacuum; one or more consumers or consumer areas of compressed gas or vacuum applications; pipelines or a network of pipelines to transport the compressed gas or vacuum from the sources to the consumers, consumer areas or applications; a plurality of sensors providing one or more physical parameters of the gas at different times and locations within the gas network. The gas network is further provided with controllable or adjustable relief valves, controllable or adjustable throttle valves and possibly one or a plurality of sensors capable of monitoring the status or state of the relief valves and/or throttle valves.

An example valve includes a housing, a sleeve disposed within the housing and having a first end and a second end opposite the first end, and the sleeve includes a plurality of sleeve protrusions at the first end and a plurality of fluid flow channels are formed between adjacent sleeve protrusions, a seal carrier disposed within the sleeve and having a carrier protrusion that extends from the second end of the sleeve and abuts against an interior surface of the housing, and an end cap mounted to the housing such that the plurality of sleeve protrusions abut against the end cap.

A system has a hydraulic circuit configured to control a position of an attachment of the system and a control system configured to perform operations that include receiving an input indicative of a center of gravity of the attachment and controlling a flow rate of fluid directed through the hydraulic circuit based on the center of gravity.

A power drive for a passenger and/or cargo elevator—or any conveyance-using stored high pressure compressed air as a primary source, producing high pressure hydraulic fluid energy to move a servo-controlled hydraulic motor, mechanically connected to the hoisting mechanism of the elevator, is disclosed. The electric power driving the air compressor is not affected by the load of the elevator (e.g. number of passengers). The electric current is consumed to charge a high pressure air tank. The compressor is operated only when the elevator is in in a parked position, thus electric power consumption level is by no means correlated to the operational mode of the elevator motion.

A flow controller that changes the flow rate of air exhausted from an air cylinder in mid-stroke includes a first switching valve displaced from a first position to a second position under the effect of pilot air, and causing one port of the air cylinder to communicate with a first channel at the first position, exhausting air exhausted from the one port of the air cylinder while reducing the flow rate of the air using a first regulating valve at the second position. Since the pilot air is taken into the first switching valve from a second channel in a system different from the system of the first channel, a second regulating valve can be adjusted without being affected by the degree of opening of the first regulating valve.

A hydraulic system in a work machine includes a travel operation device provided in a pilot oil path between a hydraulic pump a travel pump and including an operation member and configured to generate a pilot pressure supplied via the pilot oil path and an additional pilot pressure in accordance with an operation amount of the operation member. The travel pump is to control a flow direction of hydraulic oil supplied to a travel motor based on the pilot pressure and the additional pilot pressure. A pressure selection valve is provided in a first coupling oil path to select a selected pressure from the pilot pressure and the additional pilot pressure to apply the selected pressure to the pilot hydraulic oil in the second coupling oil path. A pressure adjustment valve is provided in a second coupling oil path to control the selected pressure to be an adjusted pilot pressure.