US 6,142,274 AGranted

Power take-off unit with selectively engaged brake

AssigneeDana Corporation

InventorRussell K. Warner

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Abstract

A power take-off unit includes a hydraulically actuated brake assembly which is automatically engaged when a hydraulically actuated clutch assembly is disengaged, and further which is automatically disengaged when the clutch assembly is engaged. The power take-off unit includes a housing which contains an input gear and an output shaft. The input gear is adapted to be connected to an engine or transmission of a vehicle or other source of rotational power so as to be rotatably driven in a conventional manner. The output shaft is adapted to be connected to rotatably driven accessory, such as a hydraulic pump. The power take-off unit includes a clutch assembly for selectively providing a driving connection between the input gear and the output shaft and a brake assembly for selectively exerting a braking force to retard rotation of the output shaft. When pressurized fluid is provided from a source to a clutch chamber, the clutch assembly is engaged to cause the output shaft to be rotatably driven by the input gear. Simultaneously, the pressurized fluid is fed to a brake chamber to disengage the brake assembly and permit free rotation of the output shaft. When pressurized fluid is not provided from the source to the clutch chamber, the clutch assembly is disengaged to prevent the output shaft from being rotatably driven by the input gear. At the same time, the lack of pressurized fluid in the brake chamber to engages the brake assembly and exert the braking force to retard rotation of the output shaft.

Claims11

Dependent claims

A power take-off unit adapted to be connected between an engine-driven vehicular transmission and a driven accessory, said power take-off unit comprising:

an input gear adapted to be connected to the transmission;
an output shaft adapted to be connected to the driven accessory;
a clutch assembly for selectively connecting said input gear to rotatably drive said outputd shaft, said clutch assembly including a clutch plate connected for rotation with said input gear, a friction plate connected for rotation with said output shaft, a clutch spring for normally maintaining said clutch plate and said friction plate in a disengaged relationship such that said input gear does not rotatably drive said output shaft, and a clutch piston that is responsive to fluid pressure for moving said clutch plate and said friction plate to an engaged relationship such that said input gear rotatably drives said output shaft;
and
a brake assembly for selectively retarding rotation of said output shaft, said brake assembly including a brake cyclinder that is restrained from rotation, a brake piston disposed within said brake cylinder and connected for rotation with said output shaft, and a brake spring for normally maintaining said brake cylinder and said brake piston in an engaged relationship such that said brake piston engages said brake cylinder to retard rotation of said output shaft, said brake piston being repsonsive to fluid pressure for moving said brake cylinder and said brake piston to a disengaged relationship such that said brake piston does nto engage said brake cylinder to retard rotation of said output shaft.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/774,399Filed 30 Dec 1996
Granted: 7 Nov 2000
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

F16D 55/40
Brakes with a plurality of rotating discs all lying side by side: actuated by a fluid-pressure device arranged in or one the brake
B60K 17/28
Arrangement or mounting of transmissions in vehicles: characterised by arrangement, location, or type of power take-off
F16D 67/04
Clutch-brake combinations: fluid actuated
F16D 2055/0058
Parts or details of disc brakes: fully lined, i.e. braking surface extending over the entire disc circumference