Abstract: The invention pertains to a machine tool for processing workpieces with tools, wherein the machine tool has a spindle housing that contains a spindle shaft and accommodates at least one tool as well as a drive device that causes a rotational movement of the spindle shaft. The machine tool is characterized by the fact that the drive device (3) contains a hydraulically operated displacement machine or swash plate device.

Abstract: The invention deals with a magnetically actuatable valve, in particular a hydraulic valve, with a piston guided inside of a body for establishing at least one flow-through connection, with the piston being effectively connected with two electromagnets with electric junctions and disposed on both sides of the basic body, and with the electric connection of the electromagnets being established by a sole central junction plug which is electrically connected and mechanically fixed with contact pins disposed on the electromagnets.

Abstract: A system comprising a secondary mover such as an hydraulic pump driven by a prime mover such as a motor powered, in use, by an alternating current (AC) electrical supply, whereby the operation of the secondary mover is affected by any frequency variation in a substantially constant voltage AC supply. The system further comprises adjustment means in use powered by the same AC supply as the prime mover, having inherently substantially the same operating characteristics as the prime mover, being coupled to the secondary mover and operable to adjust the operating range thereof in accordance with variations in the frequency of the AC supply.

Abstract: Control method and apparatus for a moveable control member with n>3 observed states. The apparatus incorporates a sliding mode control system operable to maintain the state point of the moveable member on a predetermined non-linear hyperplane having n-1 dimensions. The hyperplane is such that, if the state point is maintained thereon, the maximum rate of change of the highest order observed state does not exceed that of which the control apparatus is capable. The sliding mode control system include sa digital processor operable to reference n-1 low order observed states to the predetermined hyperplane to establish a desired value of the highest order observed state. The control system compares such desired value with the observed highest order state, and implements the control action necessary to maintain the state point on the predetermined hyperplane.

Abstract: Control method and apparatus for a moveable control member with n observed states, the apparatus incorporating a sliding mode control system, operable to maintain the state point of the moveable member on a predetermined hyperplane having n-1 dimensions, and comprising digital processor means operable to reference, at a first frequency, n-1 low order observed states to the predetermined hyperplane to establish a desired value of the highest order observed state, the control system further comprising comparator means operable to compare, at a second frequency, said desired value with the observed highest order state, the first frequency being less than the second frequency, and means responsive to the comparator means and operable to implement the control action necessary to maintain the state point on the predetermined hyperplane.

Abstract: Radial piston machine as a fluid pump or fluid motor comprising an inner valving trunnion, an outer cam ring and at least a cylinder block arranged therebetween and having reciprocating pistons, which tilt when the cylinder block rotates. The pistons have spherical heads and crowned piston rings along the biggest diameter or equator in order to create each an oblique sealing plane when the respective piston is tilted. Pressure in each chamber limited by said oblique sealing plane will give rise to a direct transformation of torque and fluid pressure. The valving trunnion has enlarged sealing fields to get a precompression of the fluid between high and low pressure fluid areas in order to avoid excitation of noise. The machine design can be for constant or variable displacement. In case of variable displacement, the sinusoidal curve of piston travel is adjusted for a variable preceeding angle (.epsilon.) by adding a constant eccentricity (c) so that the angle of the separation (.tau.

Abstract: The circuit provides digital control of current in an inductive load. A switching circuit generates a square wave PWM voltage drive to the load, and the current is sensed by sensor. This current is fed back as signal, which is compared with two zone boundary signals. The switching state is changed between ON and OFF accordingly.The boundary signals are generated by adding and subtracting (by adder/subtractor) a half-zone-width signal (stored as digital data) in a zone width store with the signal. The zone position may be moved slightly up and down, under control of a counter driven by the ON/OFF signal, to produce dither. The zone width may be selected in dependence on the input signal to reduce ripple at low signal, and to adjust the frequency. The switching circuitry may have multiple power supplies, and/or means for changing the connection of the load to the power supply to modify the rate of change of current and the direction of current in the load.

Abstract: A lockable adjustment mechanism (1) for an adjustable component (2), the adjustment mechanism (1) comprising a first rotatable body portion (3) adapted in use to receive and be attached to a threaded elongated adjustment member (4) of the adjustable component (2), a second non-rotatable body portion (5) attachable to the adjustable component (2) and through which the threaded adjustment member in use passes, means (7, 9) for retaining a selected relative position between the first and second body portions, a third body portion (13) rotatably mounted on the first body portion (3) and lock means (17) operable to lock the third body portion (13) to the first body portion (3), rotation of the third body (13) effecting rotation of the first body portion (3) when locked thereto and thus effecting longitudinal movement of the adjustment member (4) of the adjustable component (2), the third body portion (13) being freely rotatable when not locked to the frist body portion (3) so as not to have any effect on the setti

Abstract: A rotary, variable-displacement hydraulic pump (1) in use driven by a prime mover (4), the pump (1) comprising control means (5) for varying the displacement of the pump and means (17) responsive to a signal related to the rotational speed of the pump and operable to override the control means so as, in use, to prevent stalling of the prime mover (4) within a predetermined operational range of the prime mover.

Abstract: The invention provides a spool for a spool valve, the spool (1) comprising at least one annular land (2) having at least one notch (3) therein which is part conical (4). The invention also provides a method of producing such a spool.

Abstract: An hydraulic latch device comprises a housing having an inlet (14) for hydraulic fluid, an outlet (17) for hydraulic fluid, and first and second spool means (63,67; 62) slidably mounted in the housing and operable to control the flow of hydraulic fluid from the inlet to the outlet, each of the first and second spool means having resilient means (68;69) associated therewith and being operable to bias the spool means in one direction of sliding movement, the resilient means being arranged such that that associated with the first spool means determines the inlet pressure which places the device in a latched mode in which a first relationship is established between the inlet and outlet, and the resilient means associated with the second spool means determines the inlet pressure at which the device is placed in the unlatched mode in which mode a second relationship is established between the inlet and the outlet, with the latch pressure being higher than the unlatched pressure, and means provided to assist in main

Abstract: A gear pump or motor comprises a pair of rotary gears which are in external meshing engagement with each other. A thrust plate is pressed against the side faces of the gears by means of a plurality of pressure areas which are produced by means of a sealing and compensating unit. The unit is urged piston-like by virtue of fluid pressure chambers against the back of the thrust plate to engage it against the gears. Depending on the direction of rotation of the gears of the machine the pressure areas define the general configuration of a 3 or a .epsilon..

Abstract: A flow sensor comprises a body (4) formed with a through bore (5), at least one fluid inlet (6, 7) and one fluid outlet (7,6) for permitting ingress and egress of fluid to and from the sensor, and a spool (8) slidably mounted within the bore and having at least one shaped end (38) past which fluid flows from the inlet to the outlet, characterized in that the spool (8) also has resilient means (26) mounted internally thereof and acting against and between two spaced abutments (27, 28) which are connected to the interior of the spool in such a way that they move with the spool in one direction of movement thereof and slide relative to the spool in the opposite direction of movement thereof, the spool being arranged to close the outlet in the null position of the spool when no fluid takes place, and being movable against the action of the resilient means when fluid flow is present, to open the outlet, the extent of movement being representative of the rate of flow of the fluid and being sensed by sensor means (3

Abstract: A pilot valve for a two-stage hydraulic device, the pilot wave comprising a spool slidably mounted in a housing for movement in opposite directions from a normal null position in order to deliver fluid under pressure from an inlet port through one or other of two service ports to a second stage of the device to actuate the latter in one direction or an opposite direction from a normal null position, and an electrically-actuated spool control device, associated with one end of the spool. The pilot valve spool is movable beyond its normal operating range to an offset zero flow position in the event of a failure of a control device. A spring is disposed at one end of the pilot valve spool and is operable, in the event of failure of a control device, to move the spool to a predetermined position. A stop for the spring prevents further movement of the spool beyond the predetermined position.

Abstract: A steering power-assistance pump of vane type includes a combined flow control and pressure relief valve. When the steering valve of the steering arrangement shuts off the flow of oil, the output of the pump is converted into heat within the pump which accordingly suffers a substantial rise in temperature. The rotor of the pump and the cam ring with which the rotor vanes co-operate are combined with a pressure plate and a wear plate on respective sides of the rotor to form a unit which is displaceable in the axial direction of the pump against the force of a compressible sealing means for sealing off inlet ducts relative to a pressure chamber behind the pressure plate. The unit is thus displaced against the force of the compressible sealing means, as a result of thermally induced deformation of the housing portions of the pump. The wear and pressure plates have coatings of bearing metal on their surfaces which co-operate with the rotor, to provide better anti-friction properties.

Abstract: A pilot valve for a two-stage hydraulic device, the pilot valve comprising a spool slidably mounted in a housing for movement in opposite directions from a normal null position in order to deliver fluid under pressure from an inlet port through one or other of two service ports to a second stage of the device to actuate the latter in one direction or an opposite direction from a normal null position, and an electrically-actuated spool control device, associated with one end of the spool. The pilot valve spool is movable beyond its normal operating range to an offset zero flow position in the event of a failure of a control device. A spring is disposed at one end of the pilot valve spool and is operable, in the event of failure of a control device, to move the spool to a predetermined position. A stop for the spring prevents further movement of the spool beyond the predetermined position.

Abstract: A hydraulic pump with a falling characteristic curve in respect of the output flow relative to the pump speed. A flow control valve (40) has a spool (41) with a hollow (50) extension portion (49), and an annular chamber (52) with two control edges (53, 56) which co-operate with the valve output duct (38) and a relief duct (19) to form restrictor means which are in opposition to each other. The valve output duct (38) and the relief duct (19) are disposed substantially radially with respect to the spool.

Abstract: A hydraulic rotary vane pump comprises a flow control valve with a venturi throat disposed upstream thereof whereby the entire delivery flow from the pump passes through the venturi throat. The flow control valve is operable to control the amount of fluid flowing to the delivery outlet of the unit, under the influence of the pressure drop at a restrictor throttle in the form of a bore extending from the throat transversely with respect to the axis thereof. The angle between the axis of the venturi throat and the axis of the bore is between 90.degree. and 150.degree. depending on the degree to which the characteristic of the outlet flow produced is intended to drop off.

Abstract: A main pump (rotary vane pump 1) and a secondary pump (radial piston pump 2) are driven by way of a common shaft (3), a cam ring (30) being used to drive the secondary pump. The cam ring is coupled to the shaft (3) by way of a shear pin (33). If the auxiliary pump locks, the shear pin fractures and the cam ring (30) can rotate relative to the shaft (3). In that case, the fracture portions of the shear pin (33) are driven into their respective bores (34, 35), thereby avoiding excessive friction and overheating. Therefore, the main pump can continue to operate in spite of the failure of the auxiliary pump.

Abstract: The invention involves a new structure for a distributor for a hydraulic fluid utilization means, such as a single-acting jack, controlled by the distributor in any position. The distributor includes a spool-type valve and a hollow piston valve which is piloted by a needle valve. The needle valve and spool-type valve are both mechanically connected to a single mechanical lever.