Abstract: An electropneumatic control module for an electronically controllable pneumatic brake system for a vehicle combination with a tractor vehicle and a trailer vehicle includes a pneumatic reservoir input, which is connectable to a compressed-air reservoir, a trailer control unit, which has a trailer control valve unit with one or more electropneumatic valves, a trailer brake pressure port and a trailer supply pressure port, an immobilizing brake unit, which has a spring-type actuator port for a spring-type actuator for a tractor vehicle and an immobilizing brake valve unit with one or more electropneumatic valves, and an electronic control unit for controlling the trailer control valve unit and the immobilizing brake valve unit. The trailer control unit has a first relay valve, which has a relay valve working input connected to the reservoir input, a relay valve output connected to the trailer brake pressure port, and a relay valve ventilation output.

Abstract: A manual override assembly for a hydraulic power source operates to override an actuator of a hydraulic power source. The assembly includes a lever arm and connecting rods. The lever arm pivotally moves relative to a valve body of the hydraulic power source. The lever arm is connected to valve spools via the connecting rods, respectively. Each spool has a bore with an off-set opening for inserting one end of the connecting rod.

Abstract: A system including a programmable motion device and an end effector for grasping objects to be moved by the programmable motion device is disclosed. The system includes a vacuum source that provides a high flow vacuum such that an object may be grasped at an end effector opening while permitting a substantial flow of air through the opening, and a dead-head limitation system for limiting any effects of dead-heading on the vacuum source in the event that a flow of air to the vacuum source is interrupted.

Abstract: A hydraulic control unit comprises a housing, an accumulator, a gear pump assembly, and a motor. The housing comprises an accumulator compartment, a gear pump compartment, and a flow path section connecting the gear pump compartment and the accumulator compartment, the flow path section comprising at least a supply path and a pressurizing path. The accumulator in the accumulator compartment comprises a movable piston dividing the accumulator compartment into a high pressure reservoir and a low pressure reservoir. A gear pump assembly is in the gear pump compartment. The gear pump assembly is configured to draw return fluid from the low pressure reservoir via the supply path and to pump pressurized fluid through the pressurizing path to accumulate in the high pressure reservoir. A motor assembly is connected to the gear pump compartment of the housing and is configured to power the gear pump assembly.

Abstract: A hydraulic device for a work vehicle includes a device body, a plug, and a filler insert. The device body includes a wall structure between surfaces defining internal passages including an access passage having a first diameter extending from an access opening in the device body to a hydraulic fluid passage extending through the wall structure from an entry opening in a first surface to an exit opening in a second surface to deliver hydraulic fluid through the wall structure. A plug is mounted to the device body to close the access opening. A filler insert is proximate the plug and has a shank having a circular cross-section of a second diameter that is less than the first diameter so as to be decoupled from the inner wall surface of the access passage. An annular space around the shank in the access passage allows the hydraulic fluid to encircle at least a part of the shank of the filler insert.

Abstract: The present invention relates to a fluid control device and a connector for the same. The connector includes a first unit and a second unit to form a connector in a particular shape. Thus, the connector and an adjacent connector can be stacked upon each other to allow simple disassembling. The present invention also provides a fluid control device including the connector.

Abstract: A process control device has an electropneumatic control unit which is used for activating a pneumatic actuating drive. The control unit has a fastening module by means of which it is fastened to a drive housing of the actuating drive. The control unit includes an interface plate which is separate from the fastening module, is mounted on a top side of the fastening module and is fluidically connected, through the fastening module, to the actuating drive. The control unit includes an electrically actuatable control valve device which is fixed to the fastening module by being mounted on the interface plate fixed to the fastening module. In this way, a process control device can be produced in an easily and variably configurable manner.

Abstract: A control valve of a multi-supercharger system is provided. The control valve includes a first spool rotatably fitted in a valve body and a second spool fitted in the valve body to be coaxially rotatable together with the first spool. A disk member is installed in the valve body to partition a first chamber, in which the first spool is disposed, and a second chamber, in which the second spool is disposed, from each other. A portion of the disk member includes a communication sector, through which the first chamber and the second chamber communicate with each other. A first inlet and a first outlet are disposed in the valve body and a second inlet and a second outlet are disposed in the valve body. A first valve aperture is formed in the first spool for allowing the first spool to communicate with the communication sector.

Abstract: An excavator includes a lower travelling body; an upper turning body mounted on the lower travelling body; an engine installed in the upper turning body; a hydraulic pump connected to the engine; a hydraulic actuator driven by hydraulic oil discharged by the hydraulic pump to move a work element; a first control valve configured to control a flow rate of the hydraulic oil flowing from the hydraulic pump to the hydraulic actuator; a second control valve configured to control a flow rate of the hydraulic oil flowing from the hydraulic actuator to a hydraulic oil tank; and a control device configured to control opening and closing of the second control valve.

Abstract: A valve has a valve housing with a lid, bottom, and an intermediate housing portion between the lid bottom. The valve housing encloses a valve chamber, a flow chamber, and an actuation chamber, with at least one valve opening leading from the flow chamber to the actuation chamber. Inside the actuation chamber at least one axially movable actuator movable between a closing position to close the valve opening and an opening position to release the valve opening, one wire- or band-shaped SMA element made of a shape memory alloy to activate the actuator in the opening direction, one return element to move the actuator in closing direction, and one printed circuit board. The SMA element is attached to the actuator at a middle section and is electrically connected at its ends to the printed circuit board to be supplied with an electrical current.

Abstract: A valve has a valve housing with a lid, bottom, and an intermediate housing portion between the lid and bottom. The valve housing encloses a valve chamber with at least one valve opening and at least one axially movable actuator movable between a closing position to close the valve opening and an opening position to release the valve opening, one wire- or band-shaped SMA element made of a shape memory alloy to activate the actuator in the opening direction, one return element to move the actuator in the closing direction, and one printed circuit board. The SMA element is attached to the actuator at a middle section and is electrically connected at its ends to the printed circuit board to be supplied with an electrical current. A valve arrangement includes several of such valves.

Abstract: The present invention relates to a fluid control device and a connector for the same. The connector includes a first unit and a second unit to form a connector in a particular shape. Thus, the connector and an adjacent connector can be stacked upon each other to allow simple disassembling. The present invention also provides a fluid control device including the connector.

Abstract: An apparatus that regulates the size and intensity of a torch flame by controlling the release of oxygen and a fuel, such as propane. The apparatus releases oxygen and fuel by pivoting a flame control plate that opens and closes mini ball valves using a mini ball connecting bracket. The further forward the plate is pivoted, the more open the valves become increasing the size and intensity of the torch flame. Slotted holes at different angles on the mini ball valve connecting bracket cause the apparatus to release oxygen first resulting in a quiet flame ignition and to release oxygen last to blow out the last flow of fuel, resulting in a safe operation.

Abstract: Shock absorbers (33) are attached to a press apparatus (10). The press apparatus (10) has a lower die unit (11) and an upper die unit (21) that is movable in vertical directions; the lower die unit and the upper die unit are capable of cooperating with each other to perform press-forming on a blank (W). The upper die unit (21) has an upper forming die (22) that serves as a forming die to perform press-forming on the blank (W) and upper blank holders (25) that partially serve as blank holders. The shock absorbers (33) are respectively disposed between the upper forming die (22) and the upper blank holders (25), and when the upper die unit (21) is moved upward away from the lower die unit (11) to open the upper and lower forming dies after press-forming is performed on the blank (W), impact applied to the upper blank holders (25) by the upper forming die (22) are respectively absorbed by the shock absorbers (33).

Abstract: In a load sensing hydraulic control circuit, a pressure compensator elaborates both a load sensing pressure signal to control a pump unit and a pressure compensated power flow for actuators, the power flow being either split or alternatively directed to at least a first and a second actuator control valves so that a differential pressure across the first and second control valves is controlled by the pressure compensator. In one embodiment, the circuit is onboard a construction vehicle to power actuators such is travel left, travel right, swing, boom, arm, bucket and the like.

Abstract: A single fill valve for a cryogenic liquid storage vessel. The valve includes a central opening configured to receive a cryogenic liquid and distal and bottom openings configured to direct cryogenic liquid into the cryogenic liquid storage vessel. The valve further includes a plunger and a pin configured to move the plunger and block at least the distal and bottom openings of the single use valve.

Abstract: A safety head is disclosed. More particularly, a safety head comprising a circular flange portion and at least one protrusion is disclosed, wherein the at least one protrusion has a face exhibiting a blended radius of curvature. The circular flange portion may be thicker than the at least one protrusion. A safety head assembly is also disclosed, wherein the safety head assembly comprises an inlet safety head and an outlet safety head. Additionally, a safety head assembly is disclosed wherein the inlet safety head comprises a peripheral protrusion, the outlet safety head comprises a peripheral protrusion, and a clamp ring is configured to engage with the peripheral protrusions.

Abstract: An apparatus and method are provided for use in studying a patient's bowel which combines recording and analysis of physiologic parameters and patient sensory perception. A pain input detector, a pain transducer, and a processor are provided. A gas pressure transducer and flow meter may also be provided. Output data may be generated to reflect perceived patient pain, volume of gas delivered to the patient's bowel, and bowel pressure. An indication of perceived patient pain is processed by the processor to generate data that may used to validate a scan of a patient or may be used as a diagnostic tool.

Abstract: A valve subassembly includes a main spool having a continuously adjustable main orifice and a control spool having adjustable first and second orifices. The control spool has first and second end positions and is acted upon by a first spring toward the first end position. A fluid flow path starts from a pump and runs to an actuator via the first orifice, first control point, second orifice, second control point, main orifice, and third control point. Pressure at the first control point acts on the control spool toward the second end position and pressure at the third control point acts toward the first end position. The second orifice is closed between the first end position and an intermediate position, and opens from the intermediate position to the second end position. The second orifice opening decreases from the intermediate position to the second end position from a nonzero value to zero.

Abstract: Embodiments of the invention provide a valve-control assembly for a vehicle seat that includes a pneumatic control valve configured to control at least one seat adjustment function. A control switch is configured to operate the pneumatic control valve, and a cover structure is arranged to one or more of at least partly cover the pneumatic control valve or at least partly surround the control switch. The control switch includes a first tab, and the cover structure includes a second tab. The first tab is configured to engage the second tab, when the control switch is actuated by a predetermined amount, to secure the control switch against movement and thereby secure the pneumatic control valve in an open configuration.

Abstract: A valve assembly includes a valve body having at least a first bore and a second bore, a flow passage connecting the first bore to the second bore, a plurality of ports opening to each bore respectively, the first bore being upstream of the second bore. First and second spools are disposed in the first and second bores, respectively, for controlling the flow of fluid to and from the respective ports. A check valve is disposed in the flow passage and configured to prevent fluid flow from the second spool towards the first spool through the flow passage while allowing fluid flow from one of the ports in the first bore towards the second spool through the flow passage.

Abstract: A shovel may has a first pump that discharges a first hydraulic oil, a second pump that discharges a second hydraulic oil, a pump/motor that discharges a third hydraulic oil, an arm cylinder that at least the first hydraulic oil can flow into, and a boom cylinder that at least the second hydraulic oil can flow into. When the arm cylinder and the boom cylinder operate simultaneously, the arm cylinder is actuated by the first hydraulic oil or the third hydraulic oil, and the boom cylinder is actuated by the second hydraulic oil.

Abstract: A multi-control hydraulic circuit supplies receivers with hydraulic fluid delivered by a pump with an output controlled by the pressure of a control line depending on a load pressure of the receivers, and delivers the hydraulic fluid at a regulated pressure. The hydraulic circuit consists of hydraulic modules each associated with a receiver having a distributor which regulates the variable output supplying the receiver via a pressure compensator connected at its inlet to the outlet of the variable choke of the distributor, and at its outlet. The plunger manages the connection between its inlet and its outlet. The pressure compensator has a fluid link equipped with a choke and connects the outlet to the control line, irrespective of the position of the plunger.

Abstract: Disclosed is a configurable dynamic valve. In various embodiments the valve operates to control a pneumatic leveling system for vehicles and provide the capability for an operator to select an elevated or lowered ride height, to block air flow in and out of the leveling air bags, or to dump air from the air bags controlling the ride height. In various embodiments, the valve utilizes rotary disks which contain actuate apertures, wherein the disks form seals between ports which connect various inlet and outlet chambers such that the pneumatically selected operative disk apertures and ports provide air flow in or out of leveling air bags dynamically at a selected ride height during varying load and road conditions. In various embodiments, the modular design of the valve components allows for an easily configurable valve which may be customized to a particular application with a minimum of effort and manufacturing cost.

Abstract: A servo actuator (1) comprises an actuator housing (4); an actuator member (2) located within the actuator housing (4) and at least one spool (8) located in a cavity (6) formed within the actuator housing (4). The housing (4) also comprises a first set of internal ports including an inlet port (P), an outlet port (T) and a pair of control ports (SI, S2), the inlet port (P) being arranged for connection to a first pressurised supply and a second set of internal ports comprising an inlet port (P?), an outlet port (T?) and a pair of control ports (SI?, S2?), the inlet port (P?) being arranged for connection to a second pressurised supply. In use, movement of the spool (8) alters the flow path of fluid through the first and second set of internal ports to control the movement of the actuator member (2).

Abstract: A manual override assembly for a hydraulic power source operates to override an actuator of a hydraulic power source. The assembly includes a lever arm and connecting rods. The lever arm pivotally moves relative to a valve body of the hydraulic power source. The lever arm is connected to valve spools via the connecting rods, respectively. Each spool has a bore with an off-set opening for inserting one end of the connecting rod.

Abstract: A device for height adjustment of an operating table, including a lifting carriage which is movable relative to a chassis of the operating table, including a primary guide having a first longitudinal axis about which the lifting carriage is rotatable, including a secondary guide having a second longitudinal axis, and including a guide means which is connected to the chassis of the operating table and which has a contact area in which the guide means contacts the secondary guide in a contact area of the secondary guide.

Abstract: Hydraulic section (1) for use in a hydraulic distributor (10), comprising: a valve body (2); a main spool (3); pressure compensator (5) housed in a first hole in the valve body (2); a piston (11) housed in the first hole; an intermediate chamber (16) in fluid communication with the feed line (Pal), the intermediate chamber (16) extending at least partially in the first hole and being delimited by the rod (12) of the piston (11); two limiters (6, 7) and a drainage channel (18) pertaining to the intermediate chamber (16) for altering the pressure thereof and close the compensator (5).

Abstract: Disclosed is a flow control valve for a construction equipment for controlling the amount of oil supplied to a hydraulic actuator from a hydraulic pump.

Abstract: Disclosed is a configurable dynamic valve. In various embodiments the valve operates to control a pneumatic leveling system for vehicles and provide the capability for an operator to select an elevated or lowered ride height, to block air flow in and out of the leveling air bags, or to dump air from the air bags controlling the ride height. In various embodiments, the valve utilizes rotary disks which contain actuate apertures, wherein the disks form seals between ports which connect various inlet and outlet chambers such that the pneumatically selected operative disk apertures and ports provide air flow in or out of leveling air bags dynamically at a selected ride height during varying load and road conditions. In various embodiments, the modular design of the valve components allows for an easily configurable valve which may be customized to a particular application with a minimum of effort and manufacturing cost.

Abstract: A flow passage unit of a switching valve includes an energy-saving valve mechanism provided in a second flow passage of a flow passage body. The energy-saving valve mechanism has a movable body including a piston section and a valve member, and an elastic member that biases the movable body elastically. At a time that compressed air is supplied to the second flow passage, when a force that acts on the piston section based on the pressure of a first flow passage becomes smaller than a biasing force of the elastic member, due to the biasing force of the elastic member, the movable body is moved to a valve-closed position for blocking the second flow passage.

Abstract: A 6-way valve (20) comprises two similar 3-way sub-valves (20a, 20b) being mechanically coupled with each other, such that both sub-valves (20a, 20b) are always in the same position, whereby each sub-valve (20a, 20b) has three different valve ports (33, 34, 35) and a valve member (22?) with an internal connecting channel (29), which valve member (22?) can moved between first and second end positions via an intermediate position such that in said first end position the first (33) and third (35) valve ports are connected with each other by means of said connecting channel (29), in said second end position the second (34) and third (35) valve ports are connected with each other by means of said connecting channel (29), and in said intermediate position said connecting channel (29) is disconnected from said first and second valve ports (33, 34).

Abstract: A method for providing swerve assistance for a motor vehicle, in which a threatening or imminent collision of the motor vehicle is detected, the driver is notified to steer the vehicle onto a collision-avoiding swerve trajectory, it is detected whether the driver heeds the warning and initiates a swerve maneuver, and if the driver initiates a swerve maneuver, a driver-independent implementation of a steering or braking intervention assisting in the steering onto the swerve trajectory takes place.

Abstract: An air suspension system, comprising a manifold, defining a first and second port, each port defining a receiving region at the second end, wherein the first and second ports are arranged in a common plane, a channel intersecting the first and second port, a cavity intersecting each port, and a pressure sensor port, positioned between the first and second port, defining a sensor insertion axis normal to the common plane, the pressure sensor port separated from the first port, the second port, and the channel by a thickness; a first and second solenoid valve, each solenoid valve arranged within the cavity and coaxially arranged with the first and second ports, each solenoid valve comprising a connector; a pressure sensor arranged within the pressure sensor port, the pressure sensor comprising a connector; and an electronics module arranged parallel the common plane, the electronics module configured to electrically couple to the connectors.

Abstract: A hydraulic system is provided, the hydraulic system including a hydraulic load defining a first chamber and a second chamber. Additionally, the hydraulic system includes a pressure source, a fluid storage vessel, a load sense line, and a spool valve. The spool valve fluidly connects the fluid storage vessel to one of the first or second chambers and fluidly connects the pressure source to the other of the first or second chambers. A bypass line is also provided defining a flow path between the hydraulic load and the fluid storage vessel that bypasses the spool valve. Fluid flow may encounter less resistance through the bypass line, such that the hydraulic system may run more efficiently and with a reduced risk for cavitation in the hydraulic load.

Abstract: A system for supplying fuel to an engine of a ship. The system includes a high pressure pump pressurizing a liquefied natural gas (LNG) and supplying the pressurized LNG to the engine, a hydraulic motor driving the high pressure pump and a chamber carrying the high pressure pump and the hydraulic motor. The chamber is substantially free of electric sparks.

Abstract: A system for supplying fuel to an engine of a ship. The system includes a high pressure pump pressurizing a liquefied natural gas (LNG) and supplying the pressurized LNG to the engine, a hydraulic motor driving the high pressure pump and a chamber carrying the high pressure pump and the hydraulic motor. The chamber is substantially free of electric sparks.

Abstract: Systems and methods for cutting piles wherein, for example, a pile cutting device is attached to the end of an articulated arm of an excavator, the pile cutting device having a set of grasping arms that hold the pile and a set of saw blades that are linearly advanced to cut the pile in a single stroke. The saw blades are offset so that the cutting paths of the blades overlap. The saw blades may be positioned at the ends of telescoping arms that are coupled to a linearly movable frame. A single hydraulic unit moves the frame along a central rail. The frame is coupled to one or more cables and pulleys so that the travel of the telescopic arms is twice that of the frame.

Abstract: A directional poppet valve (10) has valve pistons (16-22) arranged in a valve housing (12) for controlling a plurality of fluid connections (A, B, P, T). The positions of each valve pistons (16-22) in the valve housing (12) can be changed by at least one actuating device. The fluid connections (A, B, P, T) are connected to one another or separated from one another alternately depending on the position of the valve pistons (16-22). The valve pistons (16-22) are arranged inline along at least one axis (R), consecutively and/or at least such as to partially interengage, in the valve housing (12).

Abstract: A valve for a hydraulic system is provided including a work port channel, a load sense channel, and a tank channel. Additionally, a body cavity extends between the work port channel and the tank channel, and a spool is movably positioned in the body cavity. The body cavity defines an inner surface and the spool defines an outer surface. The inner surface of the body cavity and the outer surface of the spool together define a interface between the body cavity and the spool that extends outwardly from a longitudinal axis, such that an increased pressure differential between the work port channel and a load sense channel increases a sealing force, allowing for a more responsive valve in the hydraulic system with less leakage.

Abstract: A valve includes a pressure limiting flow spool disposed in a valve body. The spool is movable in a first direction from a first position to a second position and in the first direction from the second position to the third position. The valve includes an inlet and a first outlet. The first position is a closed position preventing flow from the inlet to the first outlet, the second position is a maximum flow position having a maximum flow capacity from the inlet to the first outlet, and the third position is a pilot flow position having a reduced flow capacity from the inlet to the first outlet smaller than the maximum flow capacity.

Abstract: A system for supplying fuel to an engine of a ship. The system includes a high pressure pump pressurizing a liquefied natural gas (LNG) and supplying the pressurized LNG to the engine, a hydraulic motor driving the high pressure pump and a chamber carrying the high pressure pump and the hydraulic motor. The chamber is substantially free of electric sparks.

Abstract: A working valve section for a sectional fluid control valve comprising a valve section housing having a substantially planar surface for being attached to an adjacent valve section housing; a main control spool bore (43) extending into the housing substantially parallel to the planar surface; a compensator spool bore (46) extending into the housing substantially parallel to the planar surface, the compensator spool bore being spaced from the main control spool bore; a first relief slot (49a) extending across the planar surface substantially coextensive with the main control spool bore; and a second relief slot (49b) extending across the planar surface substantially coextensive with the compensator spool bore.

Abstract: Disclosed herein are an apparatus and a method for supplying a fuel to an engine of a ship. The apparatus for supplying a fuel to an engine of a ship includes: a high pressure pump pressurizing a liquefied natural gas (LNG) and supplying the pressurized LNG to the engine; a hydraulic motor driving the high pressure pump; and a lubricating pump supplying lubricating oil to the high pressure pump.

Abstract: A rotary valve that includes a rotor and a casing which rotatably accommodates the rotor. The casing includes an inflow side opening through which a fluid flows in from the outside to the rotor accommodating space and two outflow side openings through which the fluid flows out from the rotor accommodating space to the outside, at a position opposite to an outer circumferential surface of the rotor. The rotor is formed in a cylindrical shape having an internal space. An end surface of the rotor is provided with an end surface side opening which communicates with the internal space. The outer circumferential surface of the rotor is provided with a rotor outer circumferential opening and a rotor outer circumferential blocking surface which are configured to open and close the outflow side openings of the casing.

Abstract: A computer-guided system for orienting an insert during a surgical procedure, the computer-guided system comprising: a surgical table for supporting a patient, the surgical table being capable of movement about three axes; a table inertial measurement unit for measuring movement of the surgical table; a patient inertial measurement unit for measuring movement of the patient; an insert inertial measurement unit for measuring movement of the insert; and computational means for determining the relative positioning of the patient and the insert based upon movement of the surgical table, movement of the patient, and movement of the insert.

Abstract: Cooking appliance having an external control panel equipped with one or more regulating valves, where the rotary regulator organ is equipped with various peripheral openings for supplying a flow Q. For the supply of one or another type of gas, NG or LPG, either the control knob or a bezel disk in the external panel are interchangeable on the appliance, being chosen between two different available units, one and the other permitting two different angular position limits A2, A3 of the regulator organ or the supply of a constant flow Qmin through one or another opening with calibrated sections, respectively for NG or LP gas. An appendix in the control knob guided in a slide groove on the control panel of the appliance, or a tongue on the bezel disk stopping the rotation of the control knob, determines the travel limit A2 for the supply of Qmin of NG.

Abstract: The invention relates to engineering hydraulics, in particular to hydraulic drives with closed working fluid circulation. The hydraulic drive contains a hydraulic accumulator connected with a drive motor. The hydraulic pump is connected through pressure and drainage pipelines to a hydraulic distributor connected through pressure-drainage pipelines to a double-acting hydraulic motor with piston and rods. Between the pressure and drainage pipelines is connected a check valve. The hydraulic flow distributor, is made crane-type, three-position, six-way, consisting of a cylindrical body closed on one side with a cover, the other side with a pressure washer, on the shaft is mounted a control lever. In the cylindrical body and the shaft are made in two levels create alternately pressure and drainage flow passages. The hydraulic drive has a wide range of manufacturing and operating capabilities, large capacity and speed, positional accuracy of the actuators, compactness, low weight and high reliability.

Abstract: A central valve for a pivot motor actuator, the central valve including a housing tube including a first operating connection, a supply connection, a second operating connection and a tank drain connection; a piston enveloped by the housing tube and moveable relative to the housing tube, wherein the first operating connection is connected with the supply connection and the second operating connection is connected with the tank drain connection in a first position of the piston, wherein the piston is positioned in a center position in a second position, and wherein the second operating connection is connected with the supply connection and the first operating connection is connected with the tank drain connection in a third position of the piston, wherein the piston includes at least one first check valve on its outside.

Abstract: Provided is a belt-type continuously variable transmission which may prevent a servo spool from sliding even when a movable sieve slides due to reduced pressure in a hydraulic cylinder. A hydraulic servo mechanism comprises a servo spool and a feedback spool, and contiguous members coming into contact with the feedback spool (84) between a hydraulic cylinder and the feedback spool The present invention also comprises a spool position maintaining unit that makes it possible for the contiguous members to slide in relation to a movable side cylinder case when pressure in the hydraulic cylinder is lower than a predetermined value.