Abstract: The pressure supply unit has a pressure generating aggregate (10), which generates a supply pressure (PL) for the intermittent operation of a power screwdriver (11). So as to allow also a tensioning cylinder unit (33) to be operated alternatively to the power screwdriver (11), which requires higher pressure, a pressure intensifier (30) is provided which is included in a separate module (31) and generates high pressure (PH) from the supply pressure (PL). The reversal of the pressure intensifier (30) for carrying out strokes is achieved by the same stroke switch valve (20) which otherwise performs the reversal of the power screwdriver (11).

Abstract: A method for joining components using tensioning bolts, wherein the pressure is linearly increased over time when the tension bolt is hydraulically tensioned by means of a tensioning device. When a target value (Pmax) is reached, the volume is blocked so that no more hydraulic oil is supplied. The pressure decreases when the components show a setting behaviour during a holding time (tH). Pumping is resumed when a lower threshold value (PI) is reached, resulting in a pressure increase up to the target value (Pmax).

Abstract: A hydraulic aggregate comprises a container, a reservoir for hydraulic oil, and a pump driven by a motor arranged in the reservoir. The motor is a pneumatic motor. An electric control unit for controlling a main valve is mounted on the container. The main valve causes a reversal of the stroke direction of the hydraulic connections. The division into pneumatics and low power electronics leads to an explosion-proof embodiment of low weight and little technical complexity.

Abstract: The invention relates to a hydraulic group comprising a reservoir (28) for oil, in which a multiple piston pump (60) is arranged. The individual pumps (61) are cyclically driven by an eccentric ring (29). In order to ensure a permanent immersion of the individual pumps in the reservoir (28), an auxiliary reservoir (47) providing oil for refilling the reservoir (28) is arranged above the reservoir. The auxiliary reservoir (47) is connected to an additional tank (45) by means of a connection line (48).

Abstract: The pressure supply unit has a pressure generating aggregate (10), which generates a supply pressure (PL) for the intermittent operation of a power screwdriver (11). So as to allow also a tensioning cylinder unit (33) to be operated alternatively to the power screwdriver (11), which requires higher pressure, a pressure intensifier (30) is provided which is included in a separate module (31) and generates high pressure (PH) from the supply pressure (PL). The reversal of the pressure intensifier (30) for carrying out strokes is achieved by the same stroke switch valve (20) which otherwise performs the reversal of the power screwdriver (11).

Abstract: The invention relates to a method for joining components by means of tensioning bolts. According to said method, the pressure is linearly increased over time when the tensioning bolt is hydraulically tensioned by means of a tensioning device. When a target value (Pmax) is reached, the volume is blocked so that no more hydraulic oil is supplied. The pressure decreases when the components show a setting behavior during a holding time (tH). Pumping is resumed when a lower threshold value (Pi) is reached, resulting in a pressure increase up to the target value (Pmax). The invention prevents a setting process of the components from preventing that the projected pretension of the tensioning bolt is reached.

Abstract: The hydraulic aggregate comprises, within a container (10), a reservoir (11) for hydraulic oil. A pump (15) driven by a motor (18) is arranged in the reservoir (11). The motor (18) is a pneumatic motor. An electric control unit (30) for controlling a main valve (23) is mounted on the container (10). The main valve causes a reversal of the stroke direction of the hydraulic connections (13,14). The division into pneumatics and low power electronics leads to an explosion-proof embodiment of low weight and little technical complexity.

Abstract: A power wrench (10) for turning a screw is supplied by a hydraulic unit (25) that contains a positive displacement pump (26) and supplies a defined rate of flow. The pressure in a hydraulic pressure line (28) is measured by a pressure sensor (32) and provided to a control unit (31). The volume flow of the hydraulic unit (25) is determined in amount per unit of time. The piston stroke per unit of time can be determined due to the fact that the filling volume of the hydraulic cylinder is known. The piston acts upon a lever system that turns the moving part. The turning angle per unit of time can be determined due to the fact that the lever length is known. This makes it possible to dispense with an angle measuring device and to determine the turning angle merely by measuring pressure.

Abstract: A power wrench (10) for turning a screw is supplied by a hydraulic unit (25) that contains a positive displacement pump (26) and supplies a defined rate of flow. The pressure in a hydraulic pressure line (28) is measured by a pressure sensor (32) and provided to a control unit (31). The volume flow of the hydraulic unit (25) is determined in amount per unit of time. The piston stroke per unit of time can be determined due to the fact that the filling volume of the hydraulic cylinder is known. The piston acts upon a lever system that turns the moving part. The turning angle per unit of time can be determined due to the fact that the lever length is known. This makes it possible to dispense with an angle measuring device and to determine the turning angle merely by measuring pressure.

Abstract: The invention relates to a hydraulic group comprising a reservoir (28) for oil, in which a multiple piston pump (60) is arranged. The individual pumps (61) are cyclically driven by an eccentric ring (29). In order to ensure a permanent immersion of the individual pumps in the reservoir (28), an auxiliary reservoir (47) providing oil for refilling the reservoir (28) is arranged above the reservoir. The auxiliary reservoir (47) is connected to an additional tank (45) by means of a connection line (48).

Abstract: The power screwdriver comprises a functional part (11) with a housing (14) through which a shaft (17) passes. The shaft (17) is provided with a toothing (18), into which a ratchet lever of the functional part (11) engages. A splined shaft toothing (20) of the shaft (17) has an insertion recess (21) that changes into a cavity (22). The wall of the cavity (22) is provided with a torsion sensor (23) and forms a measuring section (25) that is located in the area of the shaft (17) covered by the housing (14). A torsion measurement is effected in the measuring section (25). Due to the measuring section (25) being located in the area of the shaft covered by the housing (14), the shaft (17) is relatively short whereby it may be used under tight spatial screwing conditions involving a low head height above the screw. The power wrench is additionally provided with an angle measuring device (33) whereby torque and angle of rotation can be simultaneously provided and can be used for controlling and recording.

Abstract: In the method for controlling an intermittent screw process first a torque mode (DMM) is applied in which the torque is continuously measured. Upon attainment of a pre-torque (MF) a rotation angle mode (DWM) is carried out in which the rotation angle is measured. Proceeding from the rotation angle ?=0 (corresponding to the pre-torque (MF)) the rotation angle (?) is counted up during each stroke. In this connection that torque (MHE) is stored which has been reached at the end of the stroke. During the next stroke the angle (?) is continued to be counted only when the torque (MHE) at the stroke end of the previous stroke has been reached again. Upon attainment of a target angle (?z) the screw process is terminated.

Abstract: The power screwdriver comprises a functional part (11) with a housing (14) through which a shaft (17) passes. The shaft (17) is provided with a toothing (18), into which a ratchet lever of the functional part (11) engages. A splined shaft toothing (20) of the shaft (17) has an insertion recess (21) that changes into a cavity (22). The wall of the cavity (22) is provided with a torsion sensor (23) and forms a measuring section (25) that is located in the area of the shaft (17) covered by the housing (14). A torsion measurement is effected in the measuring section (25). Due to the measuring section (25) being located in the area of the shaft covered by the housing (14), the shaft (17) is relatively short whereby it may be used under tight spatial screwing conditions involving a low head height above the screw. The power wrench is additionally provided with an angle measuring device (33) whereby torque and angle of rotation can be simultaneously provided and can be used for controlling and recording.

Abstract: In the method for controlling an intermittent screw process first a torque mode (DMM) is applied in which the torque is continuously measured. Upon attainment of a pre-torque (MF) a rotation angle mode (DWM) is carried out in which the rotation angle is measured. Proceeding from the rotation angle &agr;=0 (corresponding to the pre-torque (MF)) the rotation angle (&agr;) is counted up during each stroke. In this connection that torque (MHE) is stored which has been reached at the end of the stroke. During the next stroke the angle (&agr;) is continued to be counted only when the torque (MHE) at the stroke end of the previous stroke has been reached again. Upon attainment of a target angle (&agr;z) the screw process is terminated.