The hydraulic cylinder (26) is designed as a double action, ring-shaped compression cylinder.

The attachment unit (100) for five surface machining comprises a ring cylinder member (110) secured to the lower section of the spindle head and a clamp unit (130) directly coupled to a piston inside the cylinder member.

A pneumatic or hydraulic actuator means, preferably an annular cylinder (30), is connected between the sup-port flange (16) of the mould tube (12) and the housing (24) for axially supporting and oscillating the mould tube (12).

The hydraulic cylinder (26) is designed as a double action, ring-shaped compression cylinder.

The apparatus consists of an annular collection chamber and spin chuck.

Each operating rod is connected to the ring gate and an associated actuator.

The annular die (122) is substantially axially aligned with the ram and adapted to allow the ram (114) to pass therethrough.

The invention relates to a sealing ring for a clutch release system having an annular hydraulic working cylinder, said sealing ring being connectable to a piston of the working cylinder.

Said cylinder rod (9) comprises an annular protuberance (33) having a diameter equal to the diameter of the cylindrical wall (26).

The pressure value sensor (DA-R) located on the ring side is connected to the discharge end (38) of the valve unit (30), which can be associated with the ring side (14) of the suspension cylinder (10).

An annular tapered piston (40), providing tightness between the two cylinder chambers, is mounted sliding on the median portion (34) of the cylinder rod between the piston (7) and the annular protuberance (33).

The main cylinder (1) is a double acting cylinder, and the auxiliary cylinder (2) is a single acting cylinder.

The power cylinder (31) comprises an upper cylinder (6) and a lower cylinder (7) located beneath the upper upper cylinder(6).

The main cylinder (1) is a double acting cylinder, and the auxiliary cylinder (2) is a single acting cylinder.

The projections (36, 38) are designed so that a pressurised liquid located in the annulus (40) will substantially flow into the cylinder's working space (18).