Disclosed is a piston-cylinder assembly of a hydraulic press, which includes a basic cylinder and a first and second piston. A ring cylinder is formed above the basic cylinder as a continuation of the cylinder structure. The first piston is located inside the basic cylinder in the bottom part of the basic cylinder and the second piston is located above the first piston in the top part of the cylinder structure. The piston-cylinder assembly has a first hydraulic fluid space below the first piston and a second hydraulic fluid space below the second piston and the piston-cylinder assembly includes a unified hydraulic fluid channel in flow connection to the first hydraulic fluid space in order to provide a pressure effect in the first piston and to the second hydraulic fluid space in order to provide a pressure effect in the second piston.

Disclosed and claimed is a double-acting cylinder comprising a cylinder housing, a first floating piston, a second floating piston and a central piston which is movable to three stationary positions along an actuation direction of the cylinder. A movement of the floating pistons in the cylinder bore is delimited by end stop arrangements. A movement of the central piston in the cylinder bore is delimited by the first and the second floating piston. Each floating piston comprises a first section and a second section. A circumferential length of the floating pistons is greater in the first section than in the second section. In the first sections a first seal is arranged for a sealing engagement with an inner wall of the cylinder bore. In the second sections a second seal is arranged for a sealing engagement with the inner wall of the cylinder bore or an inner wall of the central piston.

A pneumatic actuator and control valve assembly has a housing with a control cavity for a control valve and an actuator cavity for an actuator piston and rod assembly. The control cavity and actuator cavity both have an elongated shape and are substantially parallel to each other. The control cavity has a supply port and first and second control valve outlet ports and at least one vent port with the control valve being movable through the control cavity for controlling communication between the supply port and the first and second outlet ports. The actuator cavity has first and second ports at the retracted and extended ends for shuttling the piston and within the actuator cavity between a retracted and extended end position. The housing has a first inlet and second inlet for passage of pressurized fluid to and from the housing.

Actuators and devices are provided for imparting a rotary movement and comprising in a longitudinal direction first and second hydraulic cylinders, characterised in that the first driver is a linear hydraulic cylinder comprising a first piston, and that the second driver is a linear hydraulic cylinder comprising a second piston, and in that the devices include a member for converting linear motion into rotary motion in order to convert a translation movement of the second piston into a rotary movement.

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.

An actuator device includes two drive units for an actuator output element. The first drive unit has a first piston chamber and a first piston displaceable therein and also first hydraulic means for displacing the piston. The second drive unit has a second piston chamber and a second piston displaceable therein and also second hydraulic or pneumatic means for displacing the piston. The second piston is joined to the actuator output element for conjoint movement therewith and can be coupled to the first piston for thrust, so that the second piston is displaceable in an outward direction by the first piston. The first drive unit is configured for a larger thrust force than the second drive unit, while the second drive unit is designed for a greater stroke speed than the first drive unit.

A hydraulic actuator having a body defining a chamber, a piston rod including an annular groove and a piston head slidably housed within the chamber, the piston head having a number of segments each of which has a base portion mounted within the annular groove.

A sanitary valve system (10) comprising an actuator arrangement (20) in an actuator housing (32) comprising a first piston chamber (30I) with a first piston (32I) separating the first piston chamber in a first upper cavity (34IU) and a first lower cavity (34IL) and having a first piston shaft (36I) configured to operate outside of the actuator housing. The valve system is configured to operate in multiple states. The operation of each state and transitions amongst states including identical states are controlled by regulating the liquid pressure or flow in each respective first and second upper and lower cavities. The regulation of liquid may be via a common distribution plate arrangement (90). The distribution arrangement may be with least one common distribution plate (92) with a set of canals (94) configured to connect at least one set of upper and lower regulation lines (82IU, 82IL,82IIU, 82IIL) with the respective first and second upper and communication lines (50IU, 50IL, 50IIU, 50I IL). A sanitary valve kit and a method of retrofitting an existing valve arrangement are also disclosed.

The invention relates to hydraulic cylinder devices and can be used in vehicle transmissions. A three-position pneumatic or hydraulic cylinder consists of a housing having end caps, two pistons, a rod, and supply channels for a working fluid, each piston being configured for limited movement along the rod as a result of a central protuberance, which separates the pistons, and peripheral protuberances on the rod, and being configured for limited movement inside the housing. The central protuberance is configured in the form of a bushing, and an annular protuberance is configured on the inside surface of the housing. Said bushing and said protuberance form a hermetic moveable coupling of the shaft/opening type. Separate channels are provided for supplying working fluid to the chambers formed by each piston and the corresponding end of the housing, and a shared channel is provided for supplying working fluid to the chambers formed by each piston and the central protuberance and bushing; or, separate channels are provided for supplying working fluid to the chambers formed by each piston and the central protuberance and bushing, and a shared channel is provided for supplying working fluid to the chambers formed by each piston and the corresponding end of the housing.

A pneumatic actuator and control valve assembly has a housing with a control cavity for a control valve and an actuator cavity for an actuator piston and rod assembly. The control cavity and actuator cavity both have an elongated shape and are substantially parallel to each other. The control cavity has a supply port and first and second control valve outlet ports and at least one vent port with the control valve being movable through the control cavity for controlling communication between the supply port and the first and second outlet ports. The actuator cavity has first and second ports at the retracted and extended ends for shuttling the piston and within the actuator cavity between a retracted and extended end position. The housing has a first inlet and second inlet for passage of pressurized fluid to and from the housing.