Abstract:
The invention concerns a method of producing concave, self-contained bearing surfaces, which are at least part of universal ball joints extending over the ball equator, by machining depressions pre-formed in workpieces by means of a tool having a cutting edge rotating about a rotational axis of said tool, the trajectory having a diameter which is equal to the length of a chord extending to the lowest point of the bearing surface. The cutting movement is composed of the rotary movement of the tool cutting edge and a rotating relative movement between the workpiece and tool about a vertical axis through the centre point of the ball. The feed movement is a relative movement of the tool to the workpiece along the axis of rotation of the tool inclined at the same angle of inclination relative to the vertical axis as the chord to the ball equator. In order to decrease production times and increase the dimensional accuracy of the bearing surface, the invention proposes that the chord (S) originates from the ball equator (A) and the depressed areas on both sides of the ball equator (A) be machined with two separate feed movements. The invention further concerns a bearing surface as a product of this method.
Abstract:
The invention concerns a twin pump assembly comprising two hydraulic pumps (1, 2) with mutually coaxial drive shafts (5, 6) which are interconnected in force-locking manner by means of a coupling part (23). The coupling part (23) is integrated in a connection part (26) which surrounds the coupling part at least partially and contains the intake ducts (19, 20) for the intake of the pressure medium to be delivered by the hydraulic pump (1, 2). According to the invention, the connection part (26) comprises an inlet pressure chamber (33) into which the intake ducts (19, 20) open. The coupling part (33) further comprises peripheral blade elements (30, 31) which rotate in the inlet pressure chamber (33) in order to feed the pressure medium into the intake ducts (19, 20) at an initial pressure. In a development according to the invention, the connection part (26) can be in two sections and comprise adjacent a main body (27) a cover-like closure part (29) which is dimensioned such that the coupling part (23) with its blade elements (30, 31) can be introduced into the main body (27) of the connection part (26) through the opening (34) which can be closed by the closure part (29).
Abstract:
The invention pertains to a hydrostatic drive such as a vehicle drive. It comprises a drive motor (1), a hydrostatic gear unit (2) with a hydraulic pump (3) coupled to the drive motor (1), and a hydraulic motor (4) coupled to an output-side drive shaft (11). A direct through-drive shaft (16) is provided for direct drive of the output-side drive shaft (11); the direct through-drive shaft can be detachably coupled to the drive shaft (11) via a separating clutch (17). The separating clutch (17) is fitted with two rev. counter sensors (18, 19) for the purpose of synchronising the drive motor-side speed (n1) with the drive shaft-side speed (n2). Synchronisation is achieved by applying load to or releasing load from the drive motor (1) in a controlled manner with the aid of the hydrostatic gear unit (2).
Abstract:
The invention concerns an output and moment regulation device for an adjustable hydraulic pump (1) with a hydraulic servo setter for the continuous adjustment of the delivery rate. Adjustment of the delivery rate is dependent on the delivery pressure of the hydraulic pump (1) in a delivery pressure line (10) and an actuating pressure in a control line (12), and the setter is provided with a spring (4) which forces a pump regulating member (3) in the direction of maximum delivery rate and with at least one piston (6) which acts on the pump regulating member (3) in the direction of delivery rate reduction. The piston face can be subjected via a hydraulically operated control valve (8) to the feed pressure, or is connected to a discharge (19), the control valve (8) is actuated by actuating pressure in the control line (12), and a moment valve (17) is provided whose closure force is set by a metering spring arrangement (18) connected to the pump regulating member (3) and pre-stressed in accordance with the delivery pressure setting; and the moment valve (17) connects the control line (12) to the discharge (19) in accordance with the control pressure in the control line (12) and the pre-stress in the metering spring arrangement (18); and the control line (12) which branches off from the operating pressure line (15) of the pump is provided with an adjustable choke device (13) for adjusting the control pressure acting on the control valve (8) and moment valve (17), specifically, on the closure members thereof.
Abstract:
The invention concerns a power- and moment-regulating system for at least two adjustable hydraulic pumps (10, 11), said system comprising for each hydraulic pump (10, 11) a hydraulic servo control apparatus (22, 23) for continuously adjusting the delivery. To that end, the delivery of each hydraulic pump (10, 11) is determined as a function of the delivery pressure of the respective hydraulic pump (10, 11) in a delivery pressure line (16, 17) associated with the hydraulic pump (10, 11) and the control pressures in control lines (20, 21) provided for each hydraulic pump (10, 11). Each servo control apparatus (22, 23) is provided with a moment valve (42, 43) having a valve piston (62) which can move in a valve sleeve (61) and forms a valve seat with the latter and whose closure force is determined by a measuring spring arrangement (46, 47) which is connected to the pump actuator (37, 38) and is pretensioned as a function of the set delivery. To that end, each moment valve (42; 43) connects the control line (20, 21) of the associated hydraulic pump (10; 11) to an outlet (41) as a function of the control pressure in this control line (20; 21) and the control pressure in the control line (21; 20), that is the control pressures in the control lines of the other hydraulic pump(s) (11; 10) in each case, under the pretension of the measuring spring arrangement (46; 47). According to the claimed development, for a given hydraulic pump (10; 11), the control pressure in the control line (21; 20) or the control pressures in the control lines of the other hydraulic pump(s) (11; 10) in each case act both on the valve piston (62) and on the valve sleeve (61) of the moment valve (42; 43) associated with the given hydraulic pump (10; 11).
Abstract:
The present invention pertains to a dual-function hydraulic valve (1), i.e. a control valve and a pressure reduction or limitation valve at the same time. The inventive combined hydraulic valve (1) encompasses a valve casing (2) with a first central pressure connection (P), a second central pressure connection (Br) and a movable flow check piston (7) in the valve casing (2). The flow check piston (7) presents a pressure surface (16) enabling it (P), when the first central connection is put under supply pressure (Pp), to move from its basic position against an opposing force proportional to said supply pressure (pp). It also presents a first control ridge (40) and a second control ridge (41). The first control ridge (40) is used to link the first central pressure connection (P) to the second central pressure connection (Br), starting from a first set minimum displacement of the flow check piston (7) which corresponds to a lower threshold value (p1) of the supply pressure (pp). The second control ridge (41) is used to break the linkage of the first (P) central pressure connection with both the second central pressure connection (Br) and the pressure surface (16), starting from a set maximum displacement (7) which corresponds to a higher threshold value (p2) of the supply pressure (pp).
Abstract:
The invention concerns a hydraulic control system (1), in particular for controlling the rotary mechanism of a digger. A hydraulic engine (5) is driven in a hydraulic drive circuit by means of a hydraulic pump (2), the hydraulic pump (2) and hydraulic engine (5) being connected by means of a first and a second working line (3, 4). The hydraulic control system (1) comprises an adjusting device (28) which, as a function of the differential pressure between two control lines (20, 21), displaces an adjusting piston (28a) which is disposed between two adjusting pressure chambers (26, 27) and acts on the displacement volume of the hydraulic pump (2). According to the invention, a separate brake valve (24, 25) is provided in each connection between each of the two adjusting pressure chambers (26, 27) and the pressure fluid tank (10).
Abstract:
A device is disclosed for regulating the output of at least one variable displacement pump (1) driven by a motor (6) and forcing a medium into a working line. This is done by altering the displaced volume of the pump by means of an adjusting device (7) to which an adjusting pressure (20) can be applied and which is biased in the direction of maximum displaced volume. The proposed device has a control valve (18) allocated to the adjusting device (7). The control valve can be subjected to a counter-pressure corresponding to the operating pressure in the operating line, the control valve (18) responding when the control pressure exceeds the counter-pressure, and the adjusting device (7) is acted on by the adjusting pressure to effect a reduction in the displaced volume of the variable displacement pump (1) in such a way that the product of operating pressure and displacement volume is constant. A device (25) is provided to determine the position of the adjusting device (7) and send a position signal proportional to that position to an electronic control unit (40). Also provided is a pressure limiting valve (42) by which the maximum counter-pressure in the control valve (18) can be set. The electronic control unit (40) controls the pressure limiting valve (42) in accordance with the position signal from the position sensor (25). Also disclosed is a method of controlling the output of a variable displacement pump (1) driven by a motor (6) and forcing a medium into an operating line.
Abstract:
The invention concerns an axial piston machine (1) which comprises a cylinder block (2) having cylinder bores (3, 4) in which pistons (5, 6) are movably guided, said pistons (5, 6) being supported on an inclined or wobble plate (25) in order to perform a lifting movement. The axial piston machine (1) further comprises a pivot device (31) for varying the inclination of the inclined or wobble plate (25) by pivoting about a pivot axis (27). The development according to the invention is provided with a damping element (41) which comprises a damping piston (40) which acts on the inclined or wobble plate (25) and is movably disposed in a damping cylinder (42) which is connected to a pressure fluid reservoir (48) via a throttle element (47) and a non-return valve (44) disposed parallel thereto. The non-return valve (44) enables pressure fluid to flow in an unthrottled manner from the pressure fluid reservoir (48) into the damping cylinder (42) and prevents the pressure fluid from flowing out of the damping cylinder (42) in an unthrottled manner by bypassing the throttle element (47). In this way, a damped pivot movement of the inclined or wobble plate (25) is brought about.
Abstract:
Described is a piston for a hydrostatic axial-piston machine, the surface (12) of the piston body (15) having, at the front end (Y) where it joins the end face (11) of the piston and/or at the rear end (X) near the piston head, a chamfer (16; 18; 19; 21) with a continuously changing radius of curvature.