Abstract: A hydraulic elevator may comprise a bidirectional pump that controls up and down motion of an elevator car. A VVVF drive may cause the bidirectional pump to provide working fluid in a controlled manner to a hydraulic jack that supports the elevator car. A control valve may be disposed between the bidirectional pump and the hydraulic jack so that the control valve can be closed when the elevator car needs to be held in place. To avoid pressure waves that propagate when the control valve is opened with disparate pressures on the pump and jack sides of the control valve, the bidirectional pump may adjust the pressure on the pump side of the closed control valve to the pressure on the jack side of the control valve before the control valve is opened.

Abstract: A hermetic compressor driving device, which drives a hermetic compressor provided with an HPS (High Pressure Switch) therein, includes parameter detection units (a voltage detection unit, an overcurrent detection unit, and a position and open-phase detection unit) that detect an overcurrent, a bus voltage, and an open phase, which are generated during the opening operation of the HPS within the hermetic compressor; a temperature detection unit that detects the temperature of the hermetic compressor; and a control unit to which data acquired by the parameter detection units and the temperature detection unit is input. When detecting an abnormality on the basis of the data and upon determining the abnormality as a resumable abnormality, the control unit outputs a drive signal; and, upon determining the abnormality as being not a resumable abnormality, outputs an abnormality signal so as to stop the driving of the hermetic compressor.

Abstract: The present invention relates to a control device for pressure control in a hydraulic system, especially of an elevator-system, the control device is adapted to control an output variable of an inverter supplying a hydraulic pump of the hydraulic system with electric energy, the output variable is adapted to adjust the speed of the hydraulic pump in order to at least partly compensate for a leakage of operating fluid in the hydraulic pump. Further, the invention relates to an elevator-system comprising a hydraulic pump, an inverter, and a control device which controls a supply of the hydraulic pump with electric energy from the inverter.

Abstract: The invention relates to hydraulic system for an double stacker truck comprising a pump for providing hydraulic fluid to the hydraulic system and a first hydraulic lifting cylinder for moving a first load carriage and a second hydraulic lifting cylinder for moving a second load carriage of the truck, the hydraulic lifting system is characterized in a flow divider for dividing the flow of hydraulic fluid between the first and the second hydraulic cylinder and a first directional valve which is arranged open in a first direction for leading hydraulic fluid to the first lifting cylinder or to open in a second direction for leading hydraulic fluid to the second hydraulic cylinder. The invention also relates to a double stacker truck comprising a hydraulic system for moving the load carriages of the truck.

Abstract: The hydraulic elevator system has several configurations, each incorporating the hydraulic motor and pump at the lower end of the hydraulic ram and cylinder assembly. A first embodiment utilizes a wet pump and motor assembly at the lower end of the cylinder, with the volume between the cylinder and casing providing a hydraulic reservoir. A second embodiment provides a dry pump and motor installed at the lower end of the cylinder below the surrounding casing and hydraulic reservoir. A third embodiment attaches the pump and motor to the lower end of the hydraulic ram, with the pump and motor traveling up and down with the ram during operation. Further systems facilitating the installation and removal of the hydraulic cylinder and attached components for maintenance are also provided.

Abstract: A method for modernizing a hydraulic elevator including an elevator car guided by car guide rails for moving in an essentially vertical direction in the elevator hoistway, a hydraulic system including a lifting cylinder having a cylinder part essentially vertically supported on the base of the elevator hoistway and a piston rod moving in relation to the cylinder part and a hydraulic powerpack and a control center. The hydraulic system of the hydraulic elevator is modernized to include a function for preventing unintended starting at a floor, in such a way that the hydraulic powerpack is retained and an electrically-operating valve that is monitored with a control and that acts on the flow of hydraulic fluid of the lifting cylinder is added to the hydraulic system. The control controls a valve to prevent movement of the piston rod of the lifting cylinder downwards and/or upwards, if predetermined criteria are fulfilled.

Abstract: Methods and systems for a multi-capacity vehicle lift system are provided. The system includes a lift assembly having a plurality of lift capacities and a load platform coupled to the lift assembly. The load platform includes a plurality of lift starting positions, each of the plurality of lift starting positions corresponding to a respective one of the plurality of lift capacities.

Abstract: A load weight measuring device for a multi-stage mast forklift truck has a mast assembly, an oil passage, a flow regulator valve, a pressure sensor, a detecting device, a memory, a selector, and a calculator. The mast assembly has a lift bracket for receiving a load weight, a multi-stage mast unit having masts, and a multi-stage lift cylinder unit having lift cylinders each having an oil chamber for raising the lift bracket along the masts. Hydraulic oil flows in the oil passage. The pressure sensor detects a pressure of hydraulic oil and outputs a pressure signal. The detecting device detects a state which stage of the lift cylinder raises the lift bracket and outputs a detection signal. The memory stores predetermined parameters from which the selector selects the parameter based on the detection signal. The calculator calculates the load weight based on the selected parameter and the pressure signal.

Abstract: An escape and rescue device used in a multistory building during a terrorist threat or a fire to: a) evacuate a person or persons attached to an expandable disc support with an attachment that is lowered from an upper level of a building through a vertical tube, by using a lesser pressure at the top of the tube and a higher pressure at the bottom of the tube, using a door at the top or a door at the bottom to maintain pressure or by artificial air pressure, thereby permitting the fast evacuation of many people in a short time, b) it can be used by firemen in training in its use and benefits, c) also at amusement parks, where there would be a ride that would teach the users about its reliability and safety, and d) to transport firemen in a fast way from the ground to the upper floors without interfering with the evacuation in process at the congested stairways of the building.

Abstract: An energy recovering system in a hydraulic lift device of a battery operated industrial truck. With the system, working oil can be supplied to other hydraulic actuators while energy recovering operation is performed by the hydraulic lift device, occurrence of pressure pulsation in the working oil can be prevented, and energy recovering efficiency is increased. The hydraulic lift device comprises a lift cylinder (1) for lifting a fork F, an electric motor (4) rotated by power supply from a battery (5), a hydraulic pump (3) for supplying pressurized oil to the lift cylinder (1), a control valve (14) disposed in a pressurized oil supply path (23), and a controller (17).

Abstract: An energy recovering system of a hydraulic lift device for a battery operated industrial truck. With the system, working oil can be supplied to other hydraulic actuators while energy recovering operation is performed by the hydraulic lift device, and energy recovering efficiency is increased. A hydraulic motor (6) is disposed in a fluid path for recovering pressurized working fluid from a lift cylinder (1) via a control valve (10) to a working fluid reservoir tank (8) so that the hydraulic motor (6) is driven by the pressurized working fluid returning from the lift cylinder (1). The hydraulic motor (6) is connected to an electric motor (4) for driving a hydraulic pump (3), which supplies pressurized fluid to the lift cylinder (1), by means of a one-way clutch (7) which performs torque transmission only from the hydraulic motor (6) to the electric motor (4).

Abstract: A flow control valve includes a pressure compensating valve and a first switching valve. The pressure compensating valve is configured to enlarge an opening area of a variable orifice between a load pressure line and a compensating pressure line when a pressure of working fluid of the compensating pressure line is smaller than a first set pressure, and narrow the opening area of the variable orifice when the pressure of the working fluid of the compensating pressure line is larger than the first set pressure. The first switching valve is configured to switch between a meter-out operation and a neutral operation by an external operation, wherein the working fluid of the compensating pressure line is drained in the meter-out operation, the working fluid of the compensating pressure line is not drained in the neutral operation. The load pressure line guides the working fluid to be supplied to an actuator.

Abstract: An industrial vehicle including a lifting device, a hydraulic system having two or more pump motors that provide hydraulic flow to the lifting device, a load-handling device, and a second hydraulic system fluidly coupled to the main hydraulic system. The hydraulic system diverts the hydraulic flow from one of the pump motors to the second hydraulic system when an actuation of the load handling device is detected.

Abstract: Methods and systems for a multi-capacity vehicle lift system are provided. The system includes a lift assembly having a plurality of lift capacities and a load platform coupled to the lift assembly. The load platform includes a plurality of lift starting positions, each of the plurality of lift starting positions corresponding to a respective one of the plurality of lift capacities.

Abstract: In a goods presentation arrangement with a base part (15) that can be placed on the ground by means of legs (14) and features a lifting device (16) with a lifting bottom (33) that can be raised with the aid of lifting means and carries the goods and also features a control device (40) that is assigned to the lifting device (16) and serves for controlling the lifting means, the control device (40) forms part of an exchangeable plug-in module (31) that can be inserted into a receptacle shaft (30) on the base part (15) and is arranged above the legs (14).

Abstract: An elevating device based on fluid control includes a pump and a cylinder that are connected to each other by a flow path, wherein the cylinder and a reservoir are connected to each other by a flow path via a fixed flow valve that allows fluid to flow at a predetermined flow rate. When a lowering operation of a table section is carried out, a pump-valve control unit brings a flow rate of discharge of the fluid by the pump and a flow rate of the fluid returned to the reservoir through the fixed flow valve into equilibrium and thereafter sets the flow rate of discharge of the fluid by the pump smaller than the predetermined flow rate thereby to reduce the amount of the fluid held in the cylinder.

Abstract: The invention relates to a lifting ram for lifting platforms, in particular for underfloor lifting platforms, comprising an inner tubular body (4) and an outer body (3) which is at least partially tubular and which at least partially surrounds the inner tubular body (4), wherein the outer tubular body (3) and the inner tubular body (4) are connected to one another at least in a force-fitting manner via connecting elements (5a, 5b). The lifting ram is an extruded element at least in some sections.

Abstract: An energy recovering system in a hydraulic lift device of a battery operated industrial truck. With the system, working oil can be supplied to other hydraulic actuators while energy recovering operation is performed by the hydraulic lift device, occurrence of pressure pulsation in the working oil can be prevented, and energy recovering efficiency is increased. The hydraulic lift device comprises a lift cylinder (1) for lifting a fork F, an electric motor (4) rotated by power supply from a battery (5), a hydraulic pump (3) for supplying pressurized oil to the lift cylinder (1), a control valve (14) disposed in a pressurized oil supply path (23), and a controller (17).

Abstract: A hydraulic platform lift, having hydraulic pump means and first and second hydraulic cylinders each having a piston member therein, each operatively coupled to a respective side edge of a platform to permit raising and lowering of the platform. A positive displacement valve is further provided, with the hydraulic platform lift and comprises a pair of juxtaposed cylinder members, each containing a longitudinally-movable piston, such pistons operatively coupled to each other so that movement of one piston causes an equal movement of the other. The positive displacement valve is adapted, when the pump means provides pressurized hydraulic fluid via a respective aperture to a first side of each of the pistons, to cause the pistons to be displaced an equal distance causing an equal egress of hydraulic fluid from the cylinder members via a respective aperture.

Abstract: A multistage mast assembly for use on a lift truck and method of operation for staging first and second mast sections of the multistage mast assembly. Each mast section has a retracted position and an extended position. The apparatus includes a mast staging hydraulic circuit which diverts hydraulic fluid from the second mast section actuator to the first mast section actuator using a multi-position valve having an open position and a restricted flow position. In the restricted flow position, hydraulic pressure in a hydraulic line supplying the second mast section increases to divert hydraulic fluid to the first mast section actuator before the second mast section reaches its extended position.

Abstract: A hydraulic elevator with a pressure accumulator includes a pump fir conveying hydraulic oil between the pressure accumulator and a hydraulic drive, such that the direction of rotation of the pump can be changed. An electrically controlled cylinder line stop valve is installed on one side of the pump, and an electrically controlled accumulator line stop valve is installed on the other side of the pump. Both valves are ON-OFF valves. To prevent sudden disruptive pressure changes when the valves are opened before the start of travel of the car, the pressure in the section of the line between the pump and the cylinder line stop valve and in the section of the line between the pump and the accumulator line stop valve can be varied such that, when the car is at a standstill, the pressure differences are largely eliminated before the valves are opened.

Abstract: The invention relates to a hydraulic lift comprising a pressure accumulator (17). Hydraulic fluid can be transported between the pressure accumulator (17) and a hydraulic drive (2) by means of a pump (13), the rotational direction of the pump (13) being variable. According to the invention, there is no valve between the pressure accumulator (17) and the pump (13), and means are provided for preventing the pressure accumulator (17) from being discharged when the lift is at a standstill. In terms of said means, either a screw pump is used as a pump (13), or an electrically controllable leakage stop valve (31) is arranged in a leakage line (30) extending from a leakage port of the pump (13) to the tank (21), said stop valve being closed when the lift is at a standstill. The invention enables a hydraulic lift to be operated in an energy-saving and convenient manner, using a simple hydraulic circuit, and prevents the pressure accumulator (17) from being discharged when the lift is at a standstill.

Abstract: A pump is situated between the hydraulic drive and the accumulator, this pump being driven by a motor and conveying hydraulic oil from the hydraulic drive to the accumulator and vice versa without the presence of control valves which influence the flow of hydraulic oil, such as proportionally pilot-operated valves. Since the pump is subjected to the pressure Pz in the cylinder line and the pressure Ps in the accumulator line, the motor of the pump only has to work against the differential pressure and in certain operating states, can even function as a generator and release electrical energy through a power output device controlling it. The speed of the car is controlled through the control of the motor alone by a control and regulation device, through the power output device.

Abstract: Vehicle lifting device comprising a number of columns, guides on each column for guiding a carriage for substantially vertical displacement along the column, which carriage bears vehicle supports. Lifting supports engage on the columns and the carriage. The lifting supports are connected to a motor, and a synchronization system for causing the carriages of all columns to run synchronously. The lifting supports of each column are provided with their own motor.

Abstract: A system for detecting liquid in an inground lift has a tube with an open end disposed within the internal cavity defined by the containment housing of the inground lift. The tube is in fluid communication with a source of pressurized gas. A pressure sensor generates a signal if the pressure within the air line exceeds a predetermined level, which occurs if the end is blocked by liquid. A control system is configured to respond to the signal.

Abstract: A control valve unit for a hydraulic elevator includes two control valves wherein the flow of hydraulic oil from a tank to a lifting cylinder driving an elevator cabin and/or from the lifting cylinder to the tank can be controlled. In case of an upward movement of the elevator cabin, hydraulic oil is conveyed by a pump driven by an electromotor from the tank through the control valve unit to the lifting cylinder. In the case of a downward movement of the elevator cabin, the hydraulic oil flows through the control valve unit to the tank without the pump working. The control of the upward movement and the downward movement of the elevator cabin is achieved by one single pilotable control valve, respectively, that are provided to act as a check valve as well as a proportional valve.

Abstract: The invention relates to a hydraulic lift comprising a pressure accumulator (17). Hydraulic fluid can be transported between the pressure accumulator (17) and a hydraulic drive (2) by means of a pump (13), the rotational direction of the pump (13) being variable. According to the invention, there is no valve between the pressure accumulator (17) and the pump (13), and means are provided for preventing the pressure accumulator (17) from being discharged when the lift is at a standstill. In terms of said means, either a screw pump is used as a pump (13), or an electrically controllable leakage stop valve (31) is arranged in a leakage line (30) extending from a leakage port of the pump (13) to the tank (21), said stop valve being closed when the lift is at a standstill. The invention enables a hydraulic lift to be operated in an energy-saving and convenient manner, using a simple hydraulic circuit, and prevents the pressure accumulator (17) from being discharged when the lift is at a standstill.

Abstract: A hydraulic power unit for use in conjunction with an elevator construction having an elevator car operably connected to a pair of hydraulic rams comprises a chassis having a floor and a sidewall forming a hydraulic fluid sump region. The hydraulic rams are mounted to the floor in the sump region. A hydraulic fluid reservoir is supported by the chassis, which also supports a pump/motor unit for the rams. Leveling feet mounted to the chassis allow the power unit to accommodate a variety of conditions in the hoistway pit.

Abstract: An elevator includes a special propelling fluid dynamic device which uses as a plunger the duly balanced car counterweight. The car conveys people and things upwards and downwards within a vertical conduit or hoistway supported by a cable extending to an upper pulley. When changing the direction, a counterweight is extended to balance the car. The pulley is supported from the hoistway walls and is kept in a freely-rotating condition while the balanced counterweight is a hollow piston-counterweight, accommodated in the cylinder vertically disposed in the hoistway itself and adjacent to the car. Both are integral with the propelling fluid dynamic device that produces the upward and downward movements of the car, which is completed with a circuit having a fluid flow conduit and a driving pump coupled to the valve mechanism.

Abstract: A hydraulic power unit for use in conjunction with an elevator construction having an elevator car operably connected to a pair of hydraulic rams comprises a chassis having a floor and a sidewall forming a hydraulic fluid sump region. The hydraulic rams are mounted to the floor in the sump region. A hydraulic fluid reservoir is supported by the chassis, which also supports a pump/motor unit for the rams. Leveling feet mounted to the chassis allow the power unit to accommodate a variety of conditions in the hoistway pit.

Abstract: A goods hoist having an elevator cage with controlled access arranged to move between a lower station and an upper station by a fluid pressure operated ram associated with a hoist mechanism located at the lower station and supported adjacent the upper station; the controlled access prevents access unless the cage is located at a predetermined location via safety interlocks.

Abstract: A forklift truck includes two driven front wheels, a lifting device, and at least one elevatable component. A flexible hydraulic line is wound up on a drum of the forklift truck. The hydraulic line connects the elevatable component with a non-elevatable component of the forklift truck. The drum is preferably located at least partly between the front wheels of the forklift truck. The front wheels are each driven by respective wheel motors.

Abstract: A pallet positioner includes a support frame that consists of a main upright structure with a pair of spaced, parallel outriggers extending horizontally at ground level. The distal ends of the outriggers are connected by a flat, low-profile ramp. The upright structure includes a pair of vertical guide masts rigidly mounted on a horizontal base bracing the proximal ends of the outriggers. A cantilevered carrier with a rotatable platform is mounted laterally for vertical motion along the vertical guide masts. A pneumatic bellows and an air reservoir in the base are adapted to raise and provide self-leveling to the platform. Two hydraulic cylinders provide dampening and a stabilizing effect. The flow of hydraulic fluid in the cylinders is used to control the motion of the carrier. A braking system under the platform prevents its rotation at ground level.

Abstract: A method for controlling a hydraulic elevator whose car can be displaced by a hydraulic drive mechanism by hydraulic oil fed through a cylinder line or evacuated from said hydraulic drive mechanism by a pump that cooperates with a first control valve unit and a second control valve unit, wherein the flow the hydraulic oil is controlled by a measuring device and operation of the elevator can be controlled and regulated by a control apparatus. The load of the elevator car is determined by a load pressure sensor detecting pressure PZ in the cylinder line and is controlled preferably in a constant manner by changing the control of the second control valve unit in such a way that movement of the elevator car can be controlled in a very precise manner. When the elevator car is descending, the dropping pressure PZ in the cylinder line is regulated by changing the first control valve unit in such a way that the descending movement of the elevator-cabin can also be controlled in a very precise manner.

Abstract: A hydraulic elevator with a pressure accumulator acting as a counterweight, includes a first pump for conveying hydraulic oil through a pump line, at least one valve unit, and a cylinder line to and from a hydraulic drive for a car, a second pump for conveying hydraulic oil by way of a solenoid valve from and to the pressure accumulator, which hydraulic oil can be supplied to and withdrawn from a tank. The two pumps are connected rigidly to each other and can be driven by an electric motor, the speed of which can be regulated. A single valve unit is installed between the first pump and the hydraulic drive, the valve unit being a relay-controllable valve and a first nonreturn valve connected in parallel to the relay-controllable valve. A control/automatic regulation unit is provided, and in order to control the speed of the car, acts on a power regulating unit for the electric motor, on the solenoid valve, and also, during descents, on the relay-controllable valve.

Abstract: A vertically oriented hydraulic power unit for an elevator drive includes an outer tank for drive fluid and an inner tank for fluid used to submerge and cool a motor, the fluids being exchangeable to maintain temperature in the inner tank at or below a specified maximum temperature. Oil returning from an elevator piston is fed into the inner tank to keep the inner tank sufficiently cool.

Abstract: A hydraulic platform lift for use with a truck or trailer, having hydraulic pump means and first and second hydraulic cylinders each having a piston member therein, each operatively coupled to a respective side edge of a platform to permit raising and lowering of the platform. A positive displacement valve is provided, alone and in combination with the hydraulic platform lift, which permits powered raising and lowering of the platform, and comprises a pair of juxtaposed cylinder members, each containing a longitudinally-movable piston, such pistons operatively coupled to each other so that movement of one piston causes an equal movement of the other, each cylinder member having a pair of opposite ends, one end of which having an aperture to permit ingress of hydraulic fluid from the pump means and another aperture at an opposite end to permit egress of hydraulic fluid from a corresponding cylinder member to one of the hydraulic cylinders.

Abstract: The invention pertains to a control valve unit (28) for an hydraulic elevator. It contains two control valves (5, 15) with which the flow of hydraulic oil from a tank to a lifting cylinder driving an elevator cabin and/or from said lifting cylinder to said tank can be controlled. In case of upward movement of said elevator cabin hydraulic oil is conveyed by means of a pump driven by an electromotor, from said tank through said control valve unit (28) to said lifting cylinder, whereas in case of downward movement of said elevator cabin said hydraulic oil flows through said control valve unit (28) to the tank without the pump working. In accordance with the present invention for control of the upward movement and the downward movement of said elevator cabin in said control valve unit (28) one single pilotable control valve (5, 15) respectively is provided for, each of which acts as check valve as well as as proportional valve.

Abstract: A pallet positioner includes a support frame that consists of a main upright structure with a pair of spaced, parallel outriggers extending horizontally at ground level. The distal ends of the outriggers are connected by a low-profile ramp. The upright structure includes a pair of vertical guide masts rigidly mounted on a horizontal base bracing the proximal ends of the outriggers. A pneumatically and hydraulically controlled, or electrically and hydraulically controlled, cantilevered carrier with a rotatable platform is mounted for vertical motion along the vertical guide masts. When the carrier travels downward, the carrier stops automatically at a level above the outriggers and must be manually restarted. A braking system under the platform prevents rotation thereof at ground level.

Abstract: A hydraulic elevator system of an inverter control method directly controlling a flow amount of a pressed oil discharged from a hydraulic pump by a speed control of a motor driving the hydraulic pump, which can improve energy efficiency and stability. The hydraulic elevator system includes a reverse check valve connected between a hydraulic cylinder operated by the pressed oil to lift/lower an elevator car and a hydraulic pump driven to discharge the pressed oil, opened to pass the pressed oil by the pressure of the discharged pressed oil in a driving of the hydraulic pump, and closed to prevent the pressed oil from being reversed by using a pilot pressed oil of the hydraulic cylinder as a power source in a stopping of the hydraulic pump; and a pilot hydraulic cylinder operated by the pilot pressed oil from the hydraulic cylinder in order to apply an additional close force to the reverse check valve in the lifting/lowering or emergency stopping of the elevator car.

Abstract: The hydraulic or pneumatic drive for lifting and lowering loads, in particular for lifts, has a working cylinder (11) forming a pressure chamber (14) connected to a pressure fluid source (39) and subjected to a pressure fluid. It also has a lifting piston (1) tightly guided in the working cylinder and a guide rod (15) arranged in the working cylinder. The guide rod (15) projects into the interior of the lifting piston (1) which tightly encloses the guide rod (15). The end (4) of the lifting piston (1) which projects into the pressure chamber (14) forms an annular face (5) which is subjected to pressure fluid. The interior of the lifting piston (1) forms an additional pressure chamber (7) subjected to pressure fluid and which is connected to its own pressure fluid source (40).

Abstract: A hydraulic elevator system having a configuration without a machineroom is disclosed. The hydraulic elevator system includes a valve assembly that is separated and remotely located from the pump and fluid tank. This arrangement permits the valve assembly and an electronic controller to be located in a cabinet outside of the hoistway, and the other hydraulic components, such as a tank and pump, to be located in the hoistway.

Abstract: Apparatus for use in lifting a vehicle from a substantially flat surface. The apparatus includes a pair of levers, each having a first lever and a second lever pivotally joined together cris-crossing one another and operable in a scissor-like motion between a collapsed position and a lifted position. A lifting platform is operatively coupled to the levers for supporting a vehicle thereon. A lifting mechanism is operably coupled to the levers for operating them between the collapsed position and the lifted position and thereby raising and lowering the lifting platform. An extendable, one-way incrementally lockable safety strut is pivotally connected to the first lever at a point along its upper portion and the other end of the safety strut is pivotally connected to the second lever at a point along its lower portion.

Abstract: A lift control valve is switched based on the manipulation of a lift lever, so that a lift cylinder extends or retracts to move a fork, supported on a mast, to move up or down. A check valve, which is actuated with a pilot pressure, is placed between the lift control valve and the lift cylinder. A pilot pipe led out from a pipe directly coupled to an oil tank is connected to a port of the check valve. A tilt control valve is switched based on the manipulation of a tilt lever, so that a tilt cylinder extends or retracts to tilt the mast. An electromagnetic valve is disposed between the tilt cylinder and the tilt control valve. When values necessary to drive the fork are detected, a controller control the electromagnetic valve based on those values.

Abstract: A hydraulic device for a forklift is disclosed. The forklift includes a tilting mast and a fork supported by the mast so that the fork is lifted and lowered. A tilt cylinder operates to tilt the mast by means of oil supplied by a tilt valve. A restricting valve is arranged in an oil passage connecting the tilt cylinder with the tilt valve. When the mast is tilted with the fork carrying an object and located higher than a predetermined reference position, the restricting valve closes the oil passage so that the angle of the tilting mast is limited. A check valve is arranged between the tilt cylinder and the restricting valve. The check valve blocks oil flow from the tilt cylinder to the restricting valve so that the position of the mast is maintained. This prevents unintentional movement of the mast.

Abstract: A pneumatically operated elevator has a pair of elongated vertical tubular cylindrical shafts and horizontally extending cross-over shafts extending between the vertical shafts adjacent their upper and lower ends to provide a substantially closed system. A cab is disposed within one of the vertical shafts, and a fan in at least one of the cross-over shafts moves air between the ends of the shafts to produce a pressure differential above and below the cab to cause the cab to move upwardly and downwardly in the one shaft. At least one vent is provided to admit air into at least one of the shafts to compensate for leakage from the shafts.

Abstract: A hydraulic elevator includes a car supported by at least one jack, and a fluid line for venting hydraulic fluid from the jack for lowering the car. An overspeed valve, disposed in the fluid line, comprises a housing having an inlet chamber and an outlet chamber. A piston is mounted on a stem disposed inside of the housing so as to be axially moveable, relative to the stem and housing, between an open position, allowing fluid communication between the inlet chamber and the outlet chamber, and a closed position, in which the piston at least essentially blocks fluid communication between said inlet and outlet chambers. A pressure chamber is formed behind the rearward end of the piston, and a conduit, preferably formed in the piston, allows fluid from the inlet chamber to flow into the pressure chamber. A spring, together with the pressure downstream of the valve, urge the piston towards its open position, whereas fluid in the pressure chamber urge the piston towards its closed position.

Abstract: A drive control system for an hydraulic elevator that reduces the time delay between the starting of an hydraulic pump in the system, and the first upward movement of the elevator.

Abstract: A hydraulic elevator includes a car engaged with a first hydraulic ram, a counterweight engaged with a second hydraulic ram, and a pump to transfer hydraulic fluid between the hydraulic rams. The counterweight hydraulically balances the car without the requirement of a roped connection between the car and counterweight. A fluid flow system controls the transfer of hydraulic fluid between the hydraulic rams. As a result, there is no tank or reservoir for hydraulic fluid.

Abstract: A hydraulic elevator up direction control system is provided that has a circulating valve connected between the supply and the return of a source that normally supplies pressure to the cylinder of an elevator. The circulating valve is controlled by a computer regulated stepless variable solenoid valve that influences the pilot fluid pressure in the operating chamber of the circulation valve to control the size of the opening of the circulating valve and thereby the volume of fluid passing through the circulating valve. This affects inversely the volume of fluid passing through a fluid flow measuring valve, to the cylinder, to provide selectably variable up speeds of travel facilitating a fast, smooth, accurate ride of the elevator car as it approaches a stopping point relative to an upper floor of a building. Such operation is substantially independent of the system pressure and fluid viscosity. A selectably variable speed down direction control system operates on largely the same principle.