Brake Preload and Release Assembly

Technical Field

The invention relates to the adjustment of brake discs. More particularly, the invention relates to adjusting brake discs positioned inside a wheel without disassembly of the elements inside the wheel.

Background Art

In drive assemblies it is a general practice to include a planetary gear assembly which is connected to an input shaft at one of its elements and to a rotatable output member at another of its elements. For example, the drive assembly is often associated with a wheel of a work vehicle such as a lift truck. The prime mover of the vehicle drives the sun gear of the plane¬ tary gear assembly through the input shaft. The carrier of the planetary gear assembly, for example, is con¬ nected to the wheel to rotatably drive the wheel in response to the reduced rotational output at the carrier relative to the input speed which results from the rotational input being transferred through the planetary gear assembly.

In such drive assemblies, a brake assembly is provided to slow or stop rotation of the wheel relative to the input shaft. When a disc brake is used, friction discs are commonly splined to the input shaft, while reaction discs are engaged to the frame or spindle of the drive assembly. The discs are engaged and dis¬ engaged to control the frictional force generated to slow or stop the wheel. A parking brake feature can be provided by normally engaging the discs, as through some type of biasing spring action. The brake is then released for normal operation of the vehicle through a

fluid cylinder arrangement or the like actuated to over¬ come the spring bias. Such brake assemblies are dis¬ closed, for example, in U.S. Patents 4,172,511 which issued to Khuntia et al on October 30, 1979, and 3,688,878 which issed to Barmasse on September 5, 1972. Other representative drive assemblies are shown in U.S. Patent 3,674,118 which issued to laue on July 4, 1972, and British Patent 1483731 issued to Kirkstall Forge Engineering Ltd. and published on August 24, 1977. With the normally engaged parking brake feature, however,, the discs must be released prior to towing the vehicle. Also, the discs wear during opera¬ tion and must be re-adjusted to a desirable interrela¬ tionship for proper braking operation. Heretofore, such release or adjustment has necessitated a disassembly of the drive assembly which might involve removing the wheel, the planetary gear assembly and other components to reach the brake discs and the elements adjustably maintaining the discs in their desired relationship. Such work for merely towing or to accomplish disc brake adjustment represents a waste of time and labor, par¬ ticularly in the field where work conditions may not be satisfactor .

The present invention is directed to over- coming one or more of the problems as set forth above.

Disclosure of the Invention

In one aspect of the present invention, a drive assembly has a frame, a brake assembly and a planetary gear assembly. An input member carried by the frame is positioned at a location sufficient for sup¬ porting and driving the planetary gear assembly. The brake assembly has a friction disc and a reaction disc which are continuously biased into engagement one with the other and controllably removable from engagement one

with the other. The friction and reaction discs are longitudinally movable with one of said discs being rotatably fixed relative to the frame and the other being rotatable with the input member. One of the ring and 5 carrier elements of the planetary gear assembly is of a configuration sufficient for delivering a rotational output and is controllably movable for positioning the friction and reaction discs relative to the continuous bias in a preselected engaging relationship.

10 In another aspect of the present invention, a drive assembly has a spindle and a brake assembly and a planetary gear assembly positioned inside a wheel rotatably mounted to said spindle. An input member carried by the frame is positioned at a location

15 sufficient for supporting and driving the planetary gear assembly. The brake assembly has a friction disc and a reaction disc. The discs are continuously biased into engagement one with the other and controllably removable from engagement one with the other. One of said friction

2.0 and reaction discs is rotatably fixed and longitudinally movable relative to the spindle and the other is rotatable with and longitudinally movable relative to the input member. Means is provided for moving the friction and reaction discs relative to the continuous bias through

25 adjustment at a location external of the wheel.

The brake asse ^' mbly is used to slow or stop rotation, for example, of the wheel of an associated work vehicle. The friction and reaction discs are longitudinally movable to allow engagement and

30 disengagement thereof. Adjustment of the discs for wear or complete disengagement for towing is accomplished by longitudinally moving the discs. To simplify such operations, the discs are adjustable by movement of an element of the planetary gear assembly, which can be

_. accomplished externally of the wheel and without dis¬ assembly of the drive assembly.

Brief Description of the Drawings

The drawing is a diagrammatic, cross-sectional view of a portion of a drive assembly associated with the wheel of a work vehicle and incorporating one embodiment of the present invention.

Best Mode for Carrying Out the Invention

Referring to the drawing, a drive assembly 10 is shown connected to a frame 12 of a work vehicle (not shown) , such as, for example, a lift truck. The wheel drive assembly includes a spindle 14 and a wheel 16 having an interconnected hub 18 and rim 20 and inboard and outboard sides 22,24. The wheel is rotatably mounted to the spindle which is connected to the frame. The spindle thus represents a portion of the stationary frame which can be, for example, the differential, axle housing or support frame of the vehicle. A planetary gear assembly 26 and a brake assembly 28 are included in the drive assembly and control rotational input from the drive train of the vehicle. In the embodiment shown, said gear and brake assemblies are both positioned in a bore 30 of the spindle, but can be positioned at other locations inside the wheel, as is known in the art. The brake assembly 28 includes a friction 32 and a reaction 34 disc, shown as a plurality of each, which are normally or continuously biased toward and into engagement one with the other by a biasing element 36. The biasing element is shown as a pair of frusto- conical actuator springs of the washer type which act through first and second movable chamber elements 38,40 upon the discs. The discs are controllably removable from engagement one with the other by directing fluid

into a parking brake fluid chamber 42 formed in part by the first and second chamber elements. With the discs thus removed through pressurizing the fluid chamber, the discs can also be engaged or disengaged through use of a service brake fluid chamber 44.

In order to perform the braking functions, one of the sets of friction 32 and reaction 34 discs is rotatably fixed relative to the frame 12. The other set of the discs is rotatable with an input member or shaft 46 which extends through the inboard side 22 of the wheel 16. Both sets of discs are movable relative to the frame and input member along an axis 47 of the input member. In the embodiment shown, the friction discs are engaged with the input member through mating teeth on each element which form a splined connection. The reaction discs are engaged with the spindle 14 through mating teeth of an internal gear 48 on the spindle 14 to also form a splined connection. Therefore, the friction discs can rotate with the input member and are movable axially along the axis of the input member owing to the splined connection. The reaction discs are fixed against rotation through the splined connection but are free to move axially along the axis of the input member and relative to the friction discs to frictionally engage the friction discs. Such brake disc construction and operation is v/ell known in the art and is commonly used to provide braking operations in such wheel drive assemblies.

In the brake assembly 20, a stop member 50 is positioned in abutting relationship with a disc of the one of the sets of friction 32 and reaction 34 discs rotatable with the input member 46 to locate the discs in their axial orientation relative to the biasing action of the actuator springs 36. The stop member is shown abutting one of the friction discs and engaged

with the internal gear 48 through a splined connection such that it is rotatably fixed and longitudinally movable relative to the frame 12. It will be seen that the friction and reaction discs are movable against the continuous bias of the frusto-conical actuator springs 36 in response to moving the stop member longitudinally along, or axially relative to, the input member.

The planetary gear assembly 26 has planet 52, ring 54 and carrier 56 elements and, also, a sun element 58 shown as an integral portion of the input member 46. Such planetary gear assemblies are well-known in the art. The ring element is ^* fixed relative to the frame 12 and the carrier element is of a configuration sufficient for delivering a rotational output to the wheel 16 in response to rotational input delivered through the sun and planet elements, as is known in the art. Said carrier element is also controllably movable relative to the frame 12 and the input member 46 to a location sufficient for movably positioning said friction and reaction discs in one of a preselected engaged and a disengaged relationship relative to the continuous bias. Thus, the stop member 50 is axially movable in response to moving said one of the ring and carrier elements and, in turn, the friction and reaction discs are movable between their engaged and disengaged relationships in response to axially moving the stop member.

In the embodiment shown, the spindle 14 has the ring element 54 as an integral portion thereof and the carrier element 56 is engaged or connected at flange portions (one shown) 60 with the hub 18 through bolts

(one shown) 62 to deliver the rotational output. Shims 64 are positioned between the hub and the carrier element. As will be seen from a study of the drawings, the rim 20 is also connected to the hub by the bolts. The rim can also be connected by an alternate set of

bolts through portions of the rim located at alternate intervals or different locations to the flange portions of the carrier element. A bearing 68 is positioned between the stop member 50 and the carrier element. The bearing locates the stop member and the carrier element one relative to the other and allows the carrier element to be rotatable while the stop member is rotatably fixed. The bearing also supports or maintains the stop member in axial movement with the carrier element and relative to the axis 47 of the input member by acting as a thrust bearing. The stop member, as a result, has its location determined by the position of the planetary gear assembly inside the wheel 16, yet is not affected by rotation of the related carrier element.

Industrial Applicability

In the operation of the drive assembly 10, rotational motion is delivered through the input member 46 and to the planetary gear assembly 26 from the drive train (not shown) of the associated work vehicle. Subsequent rotation of the planet elements 52 reacting on the ring element 54 causes the carrier element 56 to rotate and drive the interconnected wheel about the spindle 14. The discs 32,34 of the brake assembly 28, which are normally engaged, are disengaged during vehicle operation by introducing fluid into the parking brake fluid chamber 42. During operation, fluid de¬ livered into the service brake fluid chamber 44 control¬ lably slows or stops rotation of the wheel relative to the spindle by frictionally engaging the friction and reaction discs one with the other.

Operation of the brake assembly 28 depends upon the axial position and movement of the friction and reaction discs 32,34 to control their relative movement, and thus that of the wheel 16, in a rotational sense.

The discs are positioned in a desirable relationship by moving the stop member 50 to a position sufficient for maintaining the discs relative to the continuous bias of the actuator springs at a preselected, axially oriented location. This operation is performed by controllably moving the carrier element 56 relative to the frame 12 and input member 46 to adjust the stop member in an axial orientation relative to the axis 47 of the input member for positioning the discs relative to each other. For example, initial positioning of the discs

32,34 in the brake assembly 28 depends upon moving the discs against the continuous bias of the actuator springs 36 into engagement one with the other to provide sufficient frictional force for the parking brake function. Proper adjustment is made by controlling the number of shims 64 between the hub 18 and carrier element 56 when bolting the carrier element to the hub. It will be seen that the meshing teeth engagement of the planet element 52 and the ring and sun elements 54,58 results in the carrier element being movable relative to the brake assembly. Thus, changing the number of shims will result in placing the carrier element, and therefor the stop member 50, at a desired location to adjust the discs 32,34 as the carrier element is bolted up to hub 18.

When further adjustment is needed, the discs 32,34 can be simply moved relative to each other by changing the number of shims 64. It will be appreciated that this can be done without any disassembly of the drive assembly 10 other than removal of the wheel 16 after removal of the bolts 62 connecting the carrier element 56 and wheel to the hub 18. Thus, this particu¬ lar use of an element of the planetary gear assembly 26 provides means to move the friction and reaction discs through adjustment at a location external of the wheel

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16. In the particular embodiment shown, adjustment is provided on the outboard side 24 of the wheel. Such external adjustment is particularly useful in situations where it is desirable to tow the vehicle because only the bolts 62 need be loosened and no disassembly of the drive assembly is necessary in the field to release the brake assembly 28 from its normally engaged position. Other aspects, objects and advantages will become apparent from a study of the specification, drawings and appended claims.

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