Abstract: A method for controlling a screwdriver that has an electromotor, the electromotor having a clear ratio of rotational speed (n) to torque (M) at a defined effective voltage (Ueff soll), involving the following method step: —defining an effective voltage (Ueff soll) for operating the electromotor, —defining a cut-off rotational speed (nab) that corresponds to a pre-defined cut-off torque (Msoll) at the pre-defined effective voltage (Ueff soll), —operating the screwdriver under load with the pre-defined effective voltage (Ueff soll), —during operation of the screwdriver: —determining the rotational speed (n), —shutting down the electromotor when the cut-off rotational speed (nab) is attained.

Abstract: A method for rotating a rotatable part using a hydraulic piston-cylinder drive operated by a hydraulic pressure source and having at least one piston and a ratchet, wherein a torque is applied to the rotatable part during a loading stroke and the piston is moved into a starting position via a return stroke. The loading stroke ends when an end position of the piston is reached and subsequently the return stroke is started, wherein the end position is a position of the piston before the piston abuts against an end stop.

Abstract: A method for controlling a screwdriver that has an electromotor, the electromotor having a clear ratio of rotational speed (n) to torque (M) at a defined effective voltage (Ueff soll), involving the following method step:—defining an effective voltage (Ueff sollfor operating the electromotor,—defining a cut-off rotational speed (nab) that corresponds to a pre-defined cut-off torque (Msoll) at the pre-defined effective voltage (Ueff soll,—operating the screwdriver under load with the pre-defined effective voltage (Ueff soll,—during operation of the screwdriver:—determining the rotational speed (n),—shutting down the electromotor when the cut-off rotational speed (nab) is attained.

Abstract: A method for rotating a rotatable part using a hydraulic piston-cylinder drive operated by a hydraulic pressure source and having at least one piston and a ratchet, wherein a torque is applied to the rotatable part during a loading stroke and the piston is moved into a starting position via a return stroke. The loading stroke ends when an end position of the piston is reached and subsequently the return stroke is started, wherein the end position is a position of the piston before the piston abuts against an end stop.

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.