Patent ID: 6945371

Claim:
Wet clutch ( 100 ) or friction plate brake, with a clutch housing ( 1 ) mounted rotatably about a rotation axis (R) and essentially having the shape of a hollow cylinder, carrying an essentially ring shaped outer friction plate or a plurality of essentially ring shaped outer friction plates and displaceable in essentially the axial direction, with a clutch hub ( 2 ) mounted at least partially coaxially to the clutch housing ( 1 ), rotatable about the rotation axis (R), and essentially having the shape of a hollow cylinder, carrying one or more essentially ring shaped inner friction plates displaceable in essentially the axial direction, wherein the outer friction plates and the inner friction plates are provided alternating in the axial direction (ax) to form a friction pack such that respectively one broad surface of an outer friction plate can be brought into frictional contact with a broad surface of an inner friction plate, with an essentially hollow cylindrical shaped apply piston support device ( 12 ) provided coaxial to the clutch hub and lying radially inwardly, which is essentially rigidly connected with the clutch hub ( 2 ) by means of a connecting device ( 20 ), with an apply piston ( 8 ) essentially in the shape of a hollow cylinder, mounted essentially axially displaceable on an essentially cylindrically shaped contact surface ( 12 . 1 ) of the apply piston support device ( 12 ), including an essentially ring shaped apply piston support plate ( 8 . 8 ), wherein the apply piston support device ( 12 ) and the piston support plate ( 8 . 8 ) enclose an apply piston space ( 15 ), and including an essentially ring shaped pressure device ( 8 . 4 ), for bringing the respective contact surfaces of the friction plates of the friction pack into frictional contact, and an end plate ( 6 ) on the opposite side of said friction pack from said ring shaped pressure device ( 8 . 4 ), the improvement comprising a balance piston ( 14 ) having a cylindrical wall and a radial wall, said radial wall contacting said end plate ( 6 ) at a first contact means (A 2 ) ( 6 ), said cylindrical wall contacting said clutch hub ( 2 ) at a second contact means (A 3 ) said balance piston ( 14 ) said clutch hub ( 2 ) and said end plate ( 6 ) cooperating with said first and second contact means (A 2 and A 3 ) to define a cooling oil space ( 11 ) for receiving oil, one or more oil channels ( 9 . 1 ) providing communication between said cooling oil space ( 110 and said friction pack ( 3 ), said second contact means (A 3 ) preventing the radially outward flow of oil except through said oil channels ( 9 . 1 ), said balance piston ( 14 ) cooperating with said apply piston ( 8 ), connecting device ( 20 ) and said end plate ( 6 ) to define an equalizing space ( 16 ).