The invention relates to an actuator (1) for an automated or automatic transmission, having a cylinder housing (3), a piston unit (2), and a piston rod (13), wherein the piston unit (2) is coupled to the piston rod (13) and is arranged movably in the cylinder housing (3) along an axial longitudinal axis (4), wherein the piston unit (2) separates from each other two pressure chambers (8, 9) of variable volume in the cylinder housing (3), by means of which pressure chambers the piston unit (2) can be loaded with compressed air on both sides, wherein the two pressure chambers (8, 9) are connected to a valve unit (14) which is able to switch the pressurization or purging of each of the two pressure chambers (8, 9), and wherein an end stop damping device for damping at least one end stop of the piston unit (2) is arranged in the actuator (1). In order to improve the end stop damping device, a pneumatically and a mechanically operating damping stage are provided.

The invention relates to an actuator (1) for an automated or automatic transmission, having a cylinder housing (3), a piston unit (2), and a piston rod (13), wherein the piston unit (2) is coupled to the piston rod (13) and is arranged movably in the cylinder housing (3) along an axial longitudinal axis (4), wherein the piston unit (2) separates from each other two pressure chambers (8, 9) of variable volume in the cylinder housing (3), by means of which pressure chambers the piston unit (2) can be loaded with compressed air on both sides, wherein the two pressure chambers (8, 9) are connected to a valve unit (14) which is able to switch the pressurization or purging of each of the two pressure chambers (8, 9), and wherein an end stop damping device for damping at least one end stop of the piston unit (2) is arranged in the actuator (1). In order to improve the end stop damping device, a pneumatically and a mechanically operating damping stage are provided.

Methods and devices for controlling a mechanical joining or forming process, in particular friction drilling in thin-walled materials, apply several reverse pulses acting on a process parameter to bring the course of an actual curve of the parameter more into line with the course of a predetermined nominal curve of the process parameter. The number and length of the reverse pulses and the length of the intervals between the pulses are determined as a function of at least one immediately detectable variable associated with the process parameter.

An actuator (1) for an automated or automatic transmission has a cylinder housing (3), a piston unit (2), and a piston rod (13). The piston unit (2) is coupled to the piston rod (13) and is arranged movably in the cylinder housing (3) along a longitudinal axis (4). The piston unit (2) separates two pressure chambers (8, 9) of variable volume in the cylinder housing (3). The pressure chambers are configured to load the piston unit (2) with compressed air on both sides. The two pressure chambers (8, 9) are connected to a valve unit (14) for switching between pressurization and purging of each of the two pressure chambers (8, 9). An end stop clamping device for damping at least one end stop of the piston unit (2) is arranged in the actuator (1). A pneumatically and a mechanically operating damping stage are provided improve the end stop damping device.

An actuator (1) for an automated or automatic transmission has a cylinder housing (3), a piston unit (2), and a piston rod (13). The piston unit (2) is coupled to the piston rod (13) and is arranged movably in the cylinder housing (3) along a longitudinal axis (4). The piston unit (2) separates two pressure chambers (8, 9) of variable volume in the cylinder housing (3). The pressure chambers are configured to load the piston unit (2) with compressed air on both sides. The two pressure chambers (8, 9) are connected to a valve unit (14) for switching between pressurization and purging of each of the two pressure chambers (8, 9). An end stop clamping device for damping at least one end stop of the piston unit (2) is arranged in the actuator (1). A pneumatically and a mechanically operating damping stage are provided improve the end stop damping device.

This hydraulic drive device for a work vehicle includes a main pump (1) of a variable displacement type or a fixed displacement type discharging pressure oil, a main flow passage (F1) for supplying pressure oil of the main pump to an actuator, a sub-pump (5) of a fixed displacement type discharging pressure oil, a sub-flow passage (F2) for making pressure oil of the sub-pump merge with the main flow passage and supplying the pressure oil to the actuator (2), a merging directional valve (6A) for connecting or cutting off the main flow passage and the sub-flow passage, a controller (30) for controlling operation of the merging directional valve, and a relief valve (7A) arranged in the sub-flow passage, in which the relief valve has a pressure override characteristic having a tendency that the relief pressure increases from a cracking pressure to a set pressure as a relief flow rate increases.

In some applications, a piston of a hydraulic actuator may move at high speeds, and large undesired forces may be generated if the piston reaches an end-stop of the hydraulic actuator at a high speed. The undesired forces may, for example, cause mechanical damage in the hydraulic actuator. A controller may receive information indicative of the piston reaching a first position at a first threshold distance from the end-stop, and, in response, may modify a signal to a valve assembly controlling flow of hydraulic fluid to and from the hydraulic actuator. Further, the controller may receive information indicative of the piston reaching a second position at a second threshold distance closer to the end-stop of the hydraulic actuator, and, in response, the controller may further modify the signal to the valve assembly so as to apply a force on the piston in a away from the end-stop.

In some applications, a piston of a hydraulic actuator may move at high speeds, and large undesired forces may be generated if the piston reaches an end-stop of the hydraulic actuator at a high speed. The undesired forces may, for example, cause mechanical damage in the hydraulic actuator. A controller may receive information indicative of the piston reaching a first position at a first threshold distance from the end-stop, and, in response, may modify a signal to a valve assembly controlling flow of hydraulic fluid to and from the hydraulic actuator. Further, the controller may receive information indicative of the piston reaching a second position at a second threshold distance closer to the end-stop of the hydraulic actuator, and, in response, the controller may further modify the signal to the valve assembly so as to apply a force on the piston in a away from the end-stop.

A slewing-type work machine includes a slewing state determination section which determines whether or not slewing motion of an upper slewing body is in a deceleration state, and a capacity control section which controls a motor capacity. The capacity control section sets the motor capacity to a capacity set for a combined operation during a performance of the combined operation in which an operation for slewing the upper slewing body and an operation for actuating an attachment are performed simultaneously, while setting the motor capacity to a preset default capacity even during the performance of the combined operation when the slewing state determination section determines that the slewing motion of the upper slewing body is in the deceleration state.

A forklift includes forks, cylinders for causing the forks to perform an ascending/descending operation in accordance with the flow rate of hydraulic oil, a first valve for controlling the flow rate of the hydraulic oil in accordance with an energizing current, a second valve 6 for regulating the flow rate of the hydraulic oil in accordance with cylinder pressure, and a control portion that calculates the flow rate to be regulated by the second valve, on the basis of cylinder pressure detected by a pressure sensor, calculates a current command value for the energizing current, with the flow rate to be controlled by the first valve being set equal to the regulated flow rate, and changes the energizing current in two stages, with the current command value as the upper limit of the energizing current, thereby decelerating the forks in two stages when stopping the ascending/descending operation.