A multi-cylinder assembly includes a cylinder assembly defining a bore and a piston-rod assembly slidably disposed in the bore of the cylinder assembly. The piston-rod assembly includes a piston rod, a piston-rod sleeve and a retainer. The piston rod includes a piston head, a first rod extending outwardly from the piston head and a rod extension extending outwardly from the first rod. The piston-rod sleeve is disposed about the rod extension of the piston rod. The piston-rod sleeve includes a head portion and a rod portion. The retainer is engaged to the rod extension. The retainer prohibits axial movement of the piston-rod sleeve.

A hydraulic system and a method comprising a linear actuator 23 for generating discrete sum forces, chambers A-D for generating discrete force components, at least two charging circuits 3,4 configured to maintain predetermined pressure levels of hydraulic fluid, independent control interfaces 9-16 configured to open and close connections of the first and second charging circuits to the chambers, and an electronic control unit 50 for controlling the control interfaces. At least two control interfaces are proportional valves which are used as shut-off valves and are independently switchable to the open and closed positions in a controlled manner. Moreover, non-throttled control and secondary control are implemented in the hydraulic system and the method.

A hydraulic system and a method comprising a linear actuator 23 for generating discrete sum forces, chambers A-D for generating discrete force components, at least two charging circuits 3,4 configured to maintain predetermined pressure levels of hydraulic fluid, independent control interfaces 9-16 configured to open and close connections of the first and second charging circuits to the chambers, and an electronic control unit 50 for controlling the control interfaces. At least two control interfaces are proportional valves which are used as shut-off valves and are independently switchable to the open and closed positions in a controlled manner. Moreover, non-throttled control and secondary control are implemented in the hydraulic system and the method.

Provided is a hydraulic pressure control device and a braking system, which are capable of increasing a degree of freedom in layout of oil passages inside a housing. The hydraulic pressure control device includes a normally-closed type electromagnetic valve and a normally-open type electromagnetic valve. The normally-closed type electromagnetic valve includes a first valve part arranged so as to extend from a surface of the housing to an inside of the housing, and is configured to close an oil passage when a current is not supplied. The normally-open electromagnetic valve includes a second valve part being arranged so as to extend from the surface of the housing to the inside of the housing and having an axial length set to be equal to an axial length of the first valve part, and is configured to open the oil passage when a current is not supplied.

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 concerns a method for estimating an external force acting on an electrohydrostatic actuator, the actuator comprising a ram including a first chamber, a second chamber and a piston located between the first chamber and the second chamber, a pump capable of injecting fluid into the chambers for controlling a movement of the piston, and an electric motor driving the pump, the method comprising steps of: estimating, by means of at least one state observer (21, 22), a dynamic component and a static component of a difference in equivalent fluid pressure between the first chamber and the second chamber from a rotational speed of the electric motor, a position of the piston and a supply current of the electric motor, estimating the external force by means of a post-processing module (23) as a combination of the estimated dynamic component and static component of the difference in fluid pressure.

The invention concerns a method for estimating an external force acting on an electrohydrostatic actuator, the actuator comprising a ram including a first chamber, a second chamber and a piston located between the first chamber and the second chamber, a pump capable of injecting fluid into the chambers for controlling a movement of the piston, and an electric motor driving the pump, the method comprising steps of: estimating, by means of at least one state observer (21, 22), a dynamic component and a static component of a difference in equivalent fluid pressure between the first chamber and the second chamber from a rotational speed of the electric motor, a position of the piston and a supply current of the electric motor, estimating the external force by means of a post-processing module (23) as a combination of the estimated dynamic component and static component of the difference in fluid pressure.

A modular fluid actuator system is provided for generating a relative motion between a first fluid transfer chamber of a first module unit and a piston rod arrangement in an axial direction. The modular fluid actuator system comprises a fluid supply, a valve device coupled to the fluid supply and to the first fluid transfer chamber, a control unit coupled to the valve device for controlling the relative motion between the first fluid transfer chamber and the piston rod arrangement, the first fluid transfer chamber is coupled to a first sleeve portion exhibiting a first expandable hollow space arranged for fluid communication with the valve device via the first fluid transfer chamber.

A modular fluid actuator system is provided for generating a relative motion between a first fluid transfer chamber of a first module unit and a piston rod arrangement in an axial direction. The modular fluid actuator system comprises a fluid supply, a valve device coupled to the fluid supply and to the first fluid transfer chamber, a control unit coupled to the valve device for controlling the relative motion between the first fluid transfer chamber and the piston rod arrangement, the first fluid transfer chamber is coupled to a first sleeve portion exhibiting a first expandable hollow space arranged for fluid communication with the valve device via the first fluid transfer chamber.

A hydraulic actuating device is provided for a positive-locking shifting element of a transmission with a cylinder, in which a piston is arranged in a manner displaceable between a first end position and a second end position. The piston is a stepped piston and, with the cylinder, bounds an additional pressure chamber, which is connected to a first pressure chamber and/or a second pressure chamber through at least one hydraulic line. The volume of the additional pressure chamber decreases during an actuating movement of the piston in the direction of the first end position and increases during an actuating movement of the piston in the direction of the second end position. The degree of locking of the connection between the additional pressure chamber and the first pressure chamber and/or the second pressure chamber increases through the cylinder from a defined actuating path of the piston prior to reaching the first end position up to the first end position.