An hydraulically actuated clutch release, in particular for automobile clutches, comprising a housing having a cylindrical portion and a flange in which a port for the intake of a pressure medium is incorporated, a cylindrical sleeve, an annular piston having a flange and slidably arranged between the cylindrical sleeve and the cylindrical portion of the housing, thereby forming a pressure medium-admitting chamber, a clutch release bearing having a non-rotating bearing ring, an outer cylindrical sleeve, and a compression ring. The outer cylindrical sleeve comprises two portions of different inner diameter and a bead connecting the portions. One portion fixedly contacts the non-rotating bearing ring and the end face of the annular piston flange, and the other portion covers a portion of the outer sliding surface of the annular piston. The compression spring is arranged between the bead of the outer cylindrical sleeve and the flange of the housing.

BACKGROUND OF THE INVENTION 
The invention relates to an hydraulically activated clutch release, 
especially for automobile clutches, which comprises a cylindrical housing 
and an annular piston arranged on a cylindrical sleeve, the piston being 
connected to the clutch release bearing. 
A clutch release of the above-described type is disclosed, for example, in 
DE-GM No. 7044281. This known device has relatively complicated components 
which can become separated during travel. 
SUMMARY OF THE INVENTION 
The present invention is therefore directed to the solution of the problem 
of creating an hydraulically actuated clutch release comprised of simply 
fabricated parts which are held together by suitable means. 
In accordance with the invention, this problem is solved by providing an 
hydraulically actuated clutch release of the aforementioned type wherein 
the annular piston has a flange which abuts the end face of the 
non-rotating bearing ring facing away from the clutch. The annular piston 
is connected to the non-rotating bearing ring by means of a sleeve having 
a portion for receiving the non-rotating bearing ring and the flange 
connected to the annular piston, as well as a portion for covering the 
sliding surface of the annular piston. 
In accordance with further features of the invention, the sleeve is 
provided with a bead, which is engaged by a compression spring arranged on 
the outer surface of the sleeve and of the cylindrical housing. One end of 
the compression spring abuts an axially bent partially cutout portion of 
the bead so that the annular piston and non-rotating bearing ring of the 
clutch release bearing are secured against relative rotation. 
In addition, the rim of the sleeve portion surrounding the cylindrical 
housing can be bent radially inward in a suitable conventional manner, so 
that it engages a slotted spring ring inserted in an annular groove of the 
cylindrical housing when the annular piston is in its most axially 
extended position. In this way the annular piston, the clutch release 
bearing, and the cylindrical housing are held together as a unit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The hydraulically actuated release arrangement for clutches, in particular 
for automobile clutches, depicted in FIGS. 1-3 comprises a clutch release 
bearing 1 and an annular piston 3 slidably arranged on a cylindrical 
sleeve 2 (indicated by a dash-dot line), the piston 3 extending into the 
bore 4 of a cylindrical housing 4a. The cylindrical housing 4a is provided 
with a port 5 for the supply of a pressure medium and with a pressure 
release port 6, which are connected to a pressure medium-admitting annular 
chamber 7. The annular chamber 7 is sealed by means of two sealing rings 8 
and 9, arranged in annular grooves 10 and 11 of cylindrical housing 4a and 
cylindrical sleeve 2 respectively, and abut the outer surface and bore 
surface respectively of annular piston 3. 
The outer ring 13 of the clutch release bearing is attached to the radially 
outwardly extending flange 12 of annular piston 3, with the bearing balls 
14 arranged in a cage between the non-rotating outer ring 13 and the 
rotating inner ring 15. The thrust flange 17 of inner ring 15 is provided 
with a contacting surface 18 for the clutch diaphragm spring (not shown). 
The coupling of the clutch release bearing 1 with the annular piston 3 is 
achieved by means of a cylindrical sleeve 19. This sleeve 19 has a portion 
20 for receiving the outer ring 13 and flange 12 as well as a portion 21 
for covering the sliding surface 22 of annular piston 3. The portions 20 
and 21 are connected with each other by a bead 23. The portions 20 and 21 
have different inner diameters, so that an abutment surface 24 for 
engaging the flange 12 of annular piston 3 is formed. 
During assembly, after the insertion of the annular piston 3, the clutch 
release bearing 1, as well as the sealing discs 25 and 26 in the bore 27 
of the cylindrical sleeve 19, the rim 28 of sleeve 19 is flanged radially 
inward. The portion 21 of sleeve 19 engages a slotted wire ring 31 
arranged in an annular groove 30 of annular piston 3 by means of a 
radially inwardly bent rim 29, so that the clutch release bearing 1, the 
annular piston 3, and the cylindrical housing 4a form an integral unit. A 
compression spring 33 is arranged on the outer surface 32 of portion 21 of 
the sleeve 19 and on the cylindrical housing 4a, the spring being 
supported on one end by the bead 23 and on the other end by a flange on 
cylindrical housing 4a, thereby ensuring that the rolling elements 14 
remain continuously in contact with the races of outer ring 13 and inner 
ring 15. At a point along the circumference of the bead 23 a portion 34 
(FIG. 3) is partially cut out and bent in an axial direction. One end of 
the spring abuts this portion 34. The other end 36 of the spring is bent 
to extend axially as seen in FIG. 2, so that it can engage a projection 37 
on the cylindrical housing 4a, so that the annular piston 3 and the outer 
ring 13 are prevented from rotation by means of compression spring 33. 
The above-described embodiment represents only one embodiment of an 
hydraulically actuated release arrangement in accordance with the 
invention. Modifications may be made in the structure of the component 
parts without departing from the spirit and scope of the invention.