Dana Corporation

Parker-hannifin Corporation

Russell K Warner

Brian L Rang

Michael F Leone

Kudlip Raina

Chad A Kirkpatrick

A noise reduction structure is provided for use with a meshing gear assembly, such as in a power take-off unit for selectively providing power to one or more rotatably driven accessories. The meshing gear assembly includes meshing input and output gears that are supported within a housing and are rotatably driven during use. A helical coil wrap spring extends about and is frictionally engaged with a portion of the output gear. A first end of the wrap spring extends outwardly therefrom to form a control tang that extends adjacent to an abutment surface provided on the housing of the power take-off unit. As a result, the wrap spring is prevented from rotating relative to the housing as the output gear is rotatably driven. The wrap spring is wound and sized to frictionally engage the output gear and thereby impart a constant drag thereon as the output gear is rotated in a first rotational direction during use and to prevent the output gear from rotating in a second rotational direction opposite to the first rotational direction. As a result, the amount of noise that is generated when the power take-off unit is operated is significantly reduced.

Noise reduction structure for power take-off unit gear assembly

A power take-off unit and hydraulic control system includes an external manifold having a plurality of internal passageways formed therein. Pressurized fluid from a source is supplied to an input port provided on the manifold. A solenoid valve is mounted on the manifold and is selectively operable in a first and second mode modes to control the flow of pressurized fluid therethrough to a clutch actuation port of the power take-off unit. Low pressure fluid is supplied from a low pressure port of the manifold to the power take-off unit so as to provide internal lubricating fluid thereto. A temperature switch and a pressure switch may also be mounted directly on the manifold. A bracket or other mechanism may be provided to mount the manifold on a support surface, such as on a side rail of a frame assembly for the vehicle. Alternatively, the plurality of internal passageways may be formed within a housing for the power take-off unit. Thus, the solenoid valve, the temperature switch, and the pressure switch are all mounted directed on the housing of the power take-off unit, and no external mounting bracket or other mechanism is required.

Power take-off unit housing having integral hydraulic manifold

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.

Power take-off unit with selectively engaged brake

A wrap spring operating mechanism for use in a random start/stop clutch, brake, or combined clutch/brake assembly limits the rate of acceleration or deceleration of the second member relative to the first member when the assembly is engaged. The assembly includes a first member, a second member, and a helical spring wrapped about adjacent portions of the first and second members. An annular control collar is disposed circumferentially about portions of the first and second members. The wrap spring has a first end that is connected to the first member and a second end that is connected to the control collar. An annular armature is connected to the control collar for rotational movement therewith and for relative axial movement. An annular rotor is disposed circumferentially about and connected to the second member. An annular friction ring is disposed within a recess formed in the rotor. The friction ring is formed from a material having a relatively low coefficient of friction, preferably about 0.2 or less under both wet and dry conditions. An electromagnetic coil assembly is provided for selective moving the armature into frictional engagement with the friction ring carried on the rotor to engage the assembly. By forming the friction ring from a non-magnetically permeable material having a relatively low coefficient of friction, the time duration of the frictional engagement of the armature with the friction plate is enlarged. As a result, the rate of acceleration or deceleration of the second member relative to the first member is limited to prevent undesirable impact loads from being generated, particularly when the assembly is operated at high speeds or when relatively large load are placed thereupon.

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Nesbit, MS, United States of America

Russell K Warner