Abstract: A refrigeration system having a compressor, a condenser and an evaporator between the condenser and the compressor. A controllable valve unit at the input side of the evaporator has degrees of opening for controlling fluid flow through said evaporator. A control unit controls the degrees of opening of the valve unit. Sensors connected to the control unit and opposite ends of the evaporator detect superheat temperatures between the input and output sides of the evaporator. The control unit is operable to control the degrees of valve opening in accordance with the superheat temperatures (1) at a first greater desired opening and closing displacement rate between desired predetermined minimum and maximum values of a first range of superheat temperature values and (2) at a second opening and closing rate lesser than the first displacement rate for a second range of superheat temperature values lower than the first range of values.

Abstract: A pressure control valve of the type having pump, tank and load-sensing connections used in conjunction with one or more proportional type valves. In this type of system a load-sensing signal is tapped off from the output side of the proportional valves and conveyed to the load-sensing connection of the pressure control valve. A pressure control valve of the type herein has load-sensing and pressure chambers at opposite ends thereof with a slide valve therebetween which is spring biased towards the pressure chamber and controls the internal flow from the pump connection to the tank connection. The slide valve has an auxiliary change-over type valve which selectively connects the pressure chamber to the pump and load-sensing connections in response to a pressure differential between the pump and load-sensing connections to achieve a pressure balance between the load-sensing chamber and the pressure chamber.

Abstract: A pressure sensor unit having a pressure chamber formed in a housing by a plate member having a diaphragm region. The plate is fastened to the housing via an adhesive which is disposed in a joint between an inner housing surface and an intermediate support member which limits the movement of the adhesive in a direction transverse to the pressure direction.

Abstract: A hydraulic circuit for a backhoe loader having two double-acting cylinders for the arm and bucket of the loader and respective directional valves for the cylinders. There are heavy demands on the oil pump of the system when the two cylinders are moved simultaneously from one extreme position to another which requires substantially two whole cylinder volumes of oil. The cylinders are arranged in parallel relative to the pump. A first source of pressure medium displaced from one cylinder is used to perform work in the other cylinder and the other cylinder is also supplied with a second source of pressure medium directly from a pump. The line section through which the first source of pressure medium is supplied is shunted to a tank by valving apparatus upon a predetermined pressure being reached to freely accommodate the simultaneous movements of the cylinders.

Abstract: An electromagnetic valve assembly having upper and lower modules. A standardized lower module can be joined with one of several upper modules having a different axial length for varying the magnetic field strength of a coil arrangement in the upper module without changing the length or position of an armature tube in the lower module.

Abstract: The handwheel of a vehicle is connected to a handwheel shaft which in turn is connected through a load torque isolating device (overrunning clutch) that acts in either of the two directions of rotation and is connected to a steering shaft that controls a hydraulic arrangement. The hydraulic arrangement controls a steering motor that in turn controls the direction of turning of the vehicle. A second motor is drivingly connected to the overrunning clutch to rotate the steering shaft when the second motor is operated but when the steering is controlled by the handwheel, movement of the second motor is prevented. The second motor is operable from a location remote from the vehicle. The overrunning clutch includes a hub connected to the steering shaft and is movable by the handwheel shaft, the hub being wedgable against the clutch housing for being driven by the second motor by two jamming rollers that each acts in one direction of rotation and can be released by rotating the handwheel shaft.

Abstract: An electromagnetic valve assembly having a valve unit with a valve seat and a coil arrangement. An armature is slidably disposed in the bore of the coil arrangement. A yoke unit surrounding the coil arrangement is in two parts having cooperating longitudinally extending edges forming two axially extending air gaps on diametrically opposite sides of the yoke unit. End flange portions of the two parts of the yoke unit are cut to form articulated tabs which facilitate the forming of the flange end portions.

Abstract: A hydraulic steering system having apparatus for compensating for steering angle error. On displacement of a steering handwheel, the steering handwheel angle, the steering motor angle and the steering handwheel speed are ascertained. The fluid flow between a steering control device and a steering motor is changed via auxiliary flow paths in dependence on the steering angle error. At every steering handwheel speed and every steering angle error, the change of the fluid flow is effected in dependence on the steering handwheel speed and the steering angle error. A multiplier multiplies the outputs of a difference-generating means and a differentiator together, the output of the multiplier being connected by way of a proportional element to a valve control device connected to pass signals to a valve arrangement which controls the auxiliary flow paths.

Abstract: An electromagnetic valve assembly having a valve unit with a valve seat and a coil arrangement. An armature is slidably disposed in the bore of the coil arrangement and has one end cooperable with a core head to form an air gap and at the other end a closure device cooperable with the valve seat. The closure device has a ring shaped mounting part attached to the armature and a closure element in the form of a radially inwardly extending tongue-like part which is resiliently connected to the mounting part and is cooperable with the valve seat to maximize the operating effects of the coil arrangement.

Abstract: The control arrangement may be used for vehicles or in other steering systems and includes a steering motor that is adjusted as a function of hand operated steering mechanism, the steering mechanism controlling a directional section and a metering motor section. The directional section is fluidly connected between the steering motor and both of a tank and the metering motor section. A pump is connected between a tank and the metering motor section. The one sides of electromagnetic plus and negative valves are fluidly connected between the fluid connection of the metering motor section and the directional section while the opposite sides are respectively connected to the connection of the pump and the metering motor section and the connection of the directional section to the tank. A processing device for controlling the valves is provided for sensing the steering angle error. The control arrangement provides a simple structural arrangement to compensate for leakage.

Abstract: The valve has a valve seat disposed in the fluid flow path between the inlet and outlet and a closure member adjustable relative to the valve seat by an actuating device. A valve actuating shaft which is connected to the closure member includes an adjustment element for selectively varying the effective length of the shaft. Further, a stop member is provided in the valve housing for adjustment in the direction of movement of the closure member to block the closing movement of the closure member toward the valve seat to prevent the closure member engaging the valve seat. This ensures that there is a permanently open flow path with an adjustable throttle resistance by which a minimum flow is maintained.

Abstract: Apparatus for controlling the movement of hydraulically movable work equipment that is arranged at the end of a length-adjustable and pivotable arm, along a substantially rectilinear path of movement, the work equipment being moved with the assistance of hydraulic drive units that act on the arm in dependence on input control signals that determine the path of movement. Even in the case of non-ideal control loops for the control of the drive units, it is intended that the work equipment be moved along a desired path. For that purpose, starting from an actual position of the work equipment, a sequence of desired positions in the path of movement is ascertained and the work equipment is moved from an actual position to the next desired position, the movement into the next position not being initiated until the work equipment is located in a predetermined tolerance band about the preceding position.

Abstract: The steering system of a motor vehicle includes a steering motor having the application of pressurized fluid applied thereto by a main loop and in the event of a fault in the main loop by an auxiliary loop with the main loop isolated from the auxiliary loop. The motor includes a first and a second chamber. A first change over valve is fluidly connected to the first chamber of the motor while a second change over valve is fluidly connected to the second chamber. During normal operation the steering wheel is connected through a change over device to the main loop but in the event of a main loop fault, connected through said device to the auxiliary loop. Each loop includes a pump fluidly connected to a steering unit which is fluidly connected by one motor line connected to the first change over valve and a second motor line fluidly connected to the second change over valve.

Abstract: The procedure for monitoring leakage of incompressible fluid includes introducing a predetermined volume of testing fluid into a conduit system at a pressure about the same as that at the source of the pressurized fluid during a testing period when no fluid is being withdrawn from the conduit system and flow from the fluid source is blocked and measuring the time required for the predetermined volume to flow into the conduit system. The apparatus includes a cylinder connected in parallel with the main valve between the source and the conduit system, a movable wall in the cylinder to divide it into two chambers and a spring in the chamber for urging the wall from the conduit system side chamber together with control apparatus for sensing the volume of the last mentioned chamber decreasing to a preselected volume. The control apparatus also includes mechanism for opening and closing the main valve and monitors large and/or small leakage occurrences.

Abstract: The steering system of a motor vehicle includes a two chamber steering motor having the application of pressurized fluid applied thereto through change over valves in one position by the way of a by pass valve and alternately in a second position by the way of a steering unit. The change over valves are operated from their first position to their second position upon activation of the steering unit which results in control valve moving from a position applying pressurized fluid from a pump to the by pass valve to a position applying pressurized fluid from the pump to the steering unit.

Abstract: Method and apparatus for controlling a prior art refrigeration system of the type having an evaporator, a variable capacity compressor arrangement, and switching apparatus between a control unit and the compressor arrangement. The compressor arrangement thereof has adding and subtracting inputs which translate input signals to respectively increase or decrease step by step the effective capacity of the compressor arrangement. The switching apparatus thereof has adding and subtracting inputs and outputs and a reset output which is made effective after each increase or decrease of the effective capacity of the compressor arrangement. The method and apparatus herein involves processing a data signal which is indicative of the temperature status of the evaporator.

Abstract: A gear wheel assembly of the type having an externally toothed gear wheel and an internally toothed ring wheel with the gear wheel having one less tooth than the ring wheel and the wheels having eccentrically spaced axes with said gear wheel being rotatable about the gear wheel axis which in turn is orbitable about the ring wheel axis. Each tooth of the gear wheel has a flank on each side of the tip thereof with each said flank having a shallow recess formed thereon. Each such recess has three successive curved sections with each such recess starting and ending with the same tangent as the respective adjacent part of the associated flank. With this gear construction an automatic braking action is generated in the absence of hydraulic pressure.

Abstract: The apparatus includes a laminated core that has frontal end faces and slots with a winding extending in the slots. An electrical insulating end plate is provided adjacent at each frontal end face and adjacent to the winding heads of the winding. At least one of the end plates has a connecting box with a plurality of clamps for the ends of the windings and the terminal of a motor protection device.

Abstract: The coil arrangement of an electromagnetic valve has a stationary core that is provided with a stop face for having one end of an armature abut thereagainst. The stop face and the one end of the armature is located in a damping chamber, the other end of the armature mounting a closure member for abutting against a valve seat to block fluid flow therethrough. Between the armature and the guide member there is a throttle path that fluidly connects the damping chamber with the valve seat chamber. The electromagnetic valve is especially suitable for conveying contaminated media.

Abstract: In a hydraulic power steering control unit of the type having an inner steering wheel operated control member which has limited relative rotation movement with respect to outer control member which controls a conventional steering motor, passages are provided in these members to control the pressures therebetween to prevent jamming thereof.