A milling machine has a frame, ground engaging tracks that support the frame, a first actuator connecting the frame to a first track of the ground engaging tracks and a second actuator connecting the frame to a second track from the ground engaging tracks. The milling machine has an orientation sensor that determines an orientation of the frame. The milling machine has a controller that operates the first and second actuators to raise or lower the frame. The controller determines the frame orientation using the orientation sensor. The controller also determines a velocity error between actuator velocities of the first and second actuators based on the frame orientation and a target orientation of the frame. The controller determines a control parameter for the second actuator based on the velocity error and operates the second actuator using the determined control parameter.

A hydraulic rotary drive includes a first rotary drive element and at least two annular pistons connected to the first rotary drive element in a rotationally fixed manner and configured to be axially movable on the first rotary drive element between two end positions. Each annular piston has two annular spur serrations directed away from one another. The hydraulic rotary drive includes a second rotary drive element with ring type serrations that are complementary to the spur serrations of the annular pistons. The hydraulic rotary drive includes a control unit that is configured to control supply of hydraulic fluid to the annular pistons to cause a reciprocating movement of the annular pistons on a shaft in accordance with an operating signal. The hydraulic rotary drive includes a sensor arrangement communicatively coupled to the control unit and arranged to detect the positions of the annular pistons along respective sliding paths.

A piston for a fluid-actuated working cylinder, with a piston base unit which is coaxial to a piston longitudinal axis, consisting of a rigid core body which has radial outer peripheral surface and of an annular filling body which is seated in an annular receiving groove. The receiving groove is coaxial to the piston longitudinal axis and in the region of the radial outer peripheral surface is designed with a radially outwardly facing groove opening in the core body. The piston further includes a ring element which consists of plastic. The ring element radially outwardly coaxially encompasses the piston base unit at least in the region of the filling body, being radially supported with a radial inner peripheral surface on the piston base unit, projecting radially beyond the radial outer peripheral surface of the core body and comprising an axially orientated axial support surface radially outside the piston base unit on its two axial face sides. The piston further includes an annular enveloping body which has rubber elastic characteristics.

Locking linear actuators, thrust reversers for aircraft that include the locking linear actuators, and methods of manufacturing the locking linear actuators. The disclosed locking linear actuators include an actuator housing that defines a bore housing an actuator piston and a lock sleeve. A portion of the actuator piston defines a lock aperture, housing a locking tab capable of radial movement. When the actuator is retracted, the locking tab engages with a step in the surface of the bore to lock the linear actuator, a distal portion of the lock sleeve extends into a portion of the actuator piston to prevent the locking tab from disengaging from the step in the surface of the bore.

A fluid pressure cylinder has a sensor attachment tool mounted thereon. A holder holds the position sensor in a rail structure extending in an axial direction of a cylinder tube and is secured by screwing to a rod cover or a head cover in an arm part provided to one end of the holder.

An electro-hydraulic actuator includes: a motor output rotative power; an external gear pump activated by the motor; a hydraulic actuator operated by a pressurized working fluid supplied by the external gear pump; a manifold block in which a flow channel forming a working fluid circuit of the hydraulic actuator is incorporated; a first portion to store the motor; a second portion to store the external gear pump, the hydraulic actuator, and a reservoir; and a coupling portion to couple the first portion and the second portion in a liquid-tight state. The coupling portion includes a communication hole through which the first portion and the second portion communicate, a rotational shaft of the motor and a driving shaft of the external gear pump are joined to each other, and the external gear pump is attached to the coupling portion while being stored in the manifold block.

The invention provides an auto-lock hydraulic hoist cylinder device, comprising: a lock actuator, a lock transmission mechanism and a load-bearing mechanism, wherein the load-bearing mechanism includes load-bearing locking shaft, a load-bearing nut is provided on the load-bearing locking shaft, installed on the upper side of the upper end cover of the main hydraulic hoist, a number of protrusions is provided on the lower end of the load-bearing locking shaft, a locking cover is provided with a through hole for the load-bearing locking shaft to pass through, a groove for matching the protrusions is provided on the side wall of the through hole, a piston rod is fixed on the lower end of the locking cover, the lock actuator is provided on the upper end cover, the lock actuator drives the load-bearing locking shaft through the lock transmission mechanism.

A rotary actuator where a thrust bearing ring is positioned at an inside of a tube assembly accommodating oil, thereby reducing abrasion and damage caused by rolling friction and improving rotary power of an axle load by increasing hydraulic pressure of a piston. The rotary actuator includes the tube assembly, a piston, an axle load assembly, and a thrust bearing ring. The tube assembly is provided with a tube spiral portion where a spiral is formed at an inner circumference surface, and is formed of a first passage where oil flows into and out and a second passage spaced apart from the first passage by a fixed distance.

An extension boom system for heavy equipment having, the extension boom system including a first actuator mounted on a base, and connecting a second stage, a second actuator mounted on the second stage and connecting the second stage to a third stage, a third actuator mounted on the third stage and connecting the third stage to an extendable portion, and a controller configured to control the first actuator, the second actuator, and the third actuator so as to selectively operate in a first operation mode and a second operation mode. In the first operation mode, the first actuator, the second actuator, and the third actuator are operated substantially simultaneously, and wherein in the second operation mode, two of the first actuator, the second actuator, and the third actuator are actuated substantially simultaneously, while another of the first actuator, the second actuator, and the third actuator is not actuated.

A modular actuator assembly which can be used for partial stroke testing of a valve, the assembly having a force module and a tandem piston module. The force module has a primary piston and piston rod interconnected to a shaft which is movably mounted therein. The tandem piston module is connected to the force module and has a tandem piston and piston rod. An indicator plate is connected to the piston rod and is selectively positionable on the tandem piston rod. The tandem piston rod extends into the force module and acts as a pneumatically engaged hard stop for preventing spurious travel of the primary piston and hence spurious valve travel.