Abstract: A piston-in-piston hydraulic unit is disclosed that utilises an elastic volume to store and release energy with each stroke by varying the hydraulic fluid volumes in and out of the hydraulic unit.

Abstract: A linear hydraulic actuator comprises a hollow main piston axially moveable in an elongate cylinder under the influence of hydraulic pressure, the main piston defining a bore within which a seal member is provided, the seal member forming a sliding seal with the bore of the main piston.

Abstract: A device for controlling a pneumatic cylinder device, being of a double cylinder construction comprising an outer cylinder and an inner cylinder sealably fitted in the outer cylinder to slide along the outer cylinder. In the inner cylinder, a piston with a valve at one side thereof or valves at both sides thereof is slidably disposed. To control the valve or valves, an adjusting rod is provided which is slidably and rotatably disposed in the piston and its piston rod and adjusted by an operating lever. Alternatively, the double cylinder construction comprises a pair of cylinders disposed axially in parallel to each other. In the cylinders, pistons are disposed, one of which has a valve at one side thereof or valves at both sides thereof. The cylinders are communicated with each other by a communication construction having a communication adjusting groove and an adjusting lever for adjusting the communication area of communication adjusting groove.

Abstract: The invention relates to a feeding device for a tool slide of a machine tool of a simple, compact and economical construction comprising an electro-hydraulic linear amplifier easily accommodated in the constructional space of a hydraulically operated tool slide. The valve housing is inserted into the piston rod on the side of the piston remote from the control valve means thereby allowing for a plurality of tool slides to be arranged in a very compact space. The valve means forms a cartridge which can be simply inserted into the cylinder chamber formed by the cylinder housing. The arrangement of the control valve means in the cylinder housing and the rigid connection between the motor and the piston result in compact design and in shorter conduits for the hydraulic fluid between the control valve means and the cylinder chambers thereby leading to a high rigidity of the feeding device.