Clutch adjuster

An adjusting mechanism to compensate for clutch disc wear is located in the lever linkage of the clutch, fixed to the cover. Rotational movement axially moves an adjusting ring, thus performing the adjustment. In a first embodiment, the locking member is pushed down to release the bolt head for the adjusting mechanism to allow it to be rotated. In a second embodiment, the locking member is pushed down to release the locking member, which also engages the bolt head for the adjusting mechanism, to permit rotation of the locking member and, consequently, adjustment of the clutch. In a third embodiment, the locking member is attached by means of a fastener to the bolt head and is removed to permit adjustment.

BACKGROUND OF THE INVENTION

The present invention relates to a mechanism for adjusting spring-loaded friction clutches of large automotive vehicles. In particular, this invention relates to a clutch adjuster that secures or locks-in the adjustment and prevents rotational movement between the adjusting ring and the gear of the clutch adjuster.

Most clutches used in heavy trucks contain some type of clutch adjuster in which a manually-operated rotary gear meshes with the internal teeth of the adjusting ring to accomplish the adjustment. The rotating gear typically includes a central bolt terminating in a hex-head that is engaged by a socket wrench for rotating the gear. The clutch adjuster is locked in position by a strap that prevents rotation of the head associated with the gear. The locking and unlocking of the clutch adjuster is done by moving or removing the lock strap, which requires of manipulation of the hold-down screws that secure the strap to the clutch housing. The hold-down screws are often difficult to access, thus complicating adjustment of the clutch with this type of clutch adjuster.

This drawback was addressed by the clutch adjusters shown in Flowtow et al. U.S. Pat. No. 4,953,680. The Flowtow et al. clutch adjusters are designed to unlock by pressing the center bolt down at a reasonable force (e.g., 15 lbs.). Specifically, axial movement of the center bolt is necessary to perform the locking and unlocking of the clutch adjuster. Due to the dirty environment and the size of the ring to be rotated, the teeth of the adjusting ring and clutch adjuster can become frozen or locked. This increases substantially the force needed to axially move the center bolt to unlock the adjuster, and may make it practically impossible. Further, in the commercial version (shown inFIG. 5), the locking is “blind,” i.e., the locking surfaces are obscured from view. This leads to uncertainty as to whether locking has, in fact, occurred. If the Flowtow et al. clutch adjuster is not, in fact, locked into position, upon the first engagement of the clutch, the central bolt will rotate, and damage the locking strap. This results in gross mis-adjustment of the clutch, and the requires that the clutch adjuster be replaced.

Therefore, it is an object of the present invention to provide a clutch adjuster in which manipulation of a lock strap and mounting screws is not required.

It is a further object to provide such a clutch adjuster that provides a visual indication that the adjuster is locked into position, thus offering safety and certainty in operation.

SUMMARY OF THE INVENTION

In accordance with the present invention a clutch adjuster is provided that does not include a removable strap for locking and adjustment operation. The clutch adjuster includes a bracket having a central depressed area between two arms. In a first embodiment, a locking member is provided that is placed under the head of the adjusting bolt in the central area of the bracket. The locking member is biased upwardly into engagement with the head of the adjusting bolt by, e.g., a waved or spring washer. While a spring washer is shown in the illustrated embodiment, other biasing or resilient means may be used interchangeably, such as a spring, a compressible rubber washer, etc. The locking member is pushed down with a socket wrench, releasing the head of the bolt, and allowing the bolt to be freely rotated by the socket wrench. Upon removal of the socket wrench, the lock is returned to its initial position by the force of the spring, which thus engages and locks the head of the bolt. The relative position between the head of the bolt and the locking member is visible, thus allowing corrective rotation of the bolt, if necessary, to assure the locking. Rotation of the locking member, and thus the central bolt when engaged by the locking member, is prevented by the arms of the bracket.

In a second embodiment, a locking and adjusting member is provided that is in axial alignment with the bolt and is moveable between adjusting and locking positions. The locking and adjusting member includes a socket shaped to engage the head of the bolt, a head adapted to be engaged by a tool, and opposed shoulders beneath the head. The arms of the bracket further comprise locking arms that extend at least partially over the central area and are adapted to engage the opposed shoulders on the locking and adjusting member when in the locking position. The locking and adjusting member is biased toward the locking position by a resilient member, such as a spring.

In a third embodiment of the invention, the locking member overlies the head of the bolt and is removeably attached to the center bolt by a screw to permit adjustment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring toFIG. 1, there is schematically illustrated a conventional friction clutch10which incorporates a first preferred embodiment of a clutch adjuster20. Turning toFIGS. 2 and 3, the adjuster20includes a strap or bracket24with two generally L-shaped arms24athat flank a central depressed area24b. The central area24bincludes an aperture that captures the central bolt30which carries a rotary gear or sprocket25. The teeth of the sprocket25are configured to engage the teeth of a clutch adjusting ring15. The adjuster20is secured to the clutch cover12by two bolts14.

With reference toFIGS. 2 and 3, the adjuster20includes a central bolt30which has a head32(preferably hex- or square-shaped) adapted to be engaged by a torque-applying tool, such as a socket wrench. The shaft of the bolt30is captured for rotation in an aperture in the central area24bof the bracket24. As illustrated, the shaft of the bolt30has different diameters for proper assembly with the remainder of the components. Specifically, the portion of the shaft immediately beneath the head32is enlarged with respect to the remainder of the shaft so as to not be capable of passing through the aperture in the bracket24. The rotary gear25is secured to the lower portion of the shaft30so as to substantially prevent axial movement of the bolt30with respect to the bracket24.

A locking member22is mounted to the enlarged portion of the shaft of the bolt30immediately under the head32of the central bolt30. The locking member22is configured with a recessed portion22abetween two opposed raised portions22b(best seen inFIG. 3), which are adapted to engage two sides of the head32of the bolt30when in the locking position. The locking member22seats in the central portion24bof the bracket24between the two L-shaped arms24aso that rotation of the locking member22with respect to the bracket24is prevented. As illustrated, a spring washer26is positioned between the locking member22and the bracket24to bias the lock in a upward direction, thus engaging the shaped head of the bolt, which would otherwise rotate freely. As noted above, other resilient means may be substituted for the spring washer. The spring26should have a resiliency such that the force required to move the locking member22out of engagement with the head32of the bolt30is approximately 8 pounds. This force remains constant regardless of the condition of the clutch components. Consequently, by using a socket wrench, locking member22can be pushed down against the force of the spring washer26, and the shaped head32will be free to rotate along with sprocket25upon rotation of the wrench, thus making the clutch adjustment possible. By removing the socket wrench, the spring washer26biases the locking member22upwardly to capture and lock the head. Since whether locking engagement has occurred can be easily visually confirmed, damage to the clutch or accidents due to the clutch adjuster not being properly locked can be avoided. For better visibility, the locking member22and the bracket24can be of contrasting colors.

Turning toFIGS. 4 and 5, a second embodiment of a clutch adjuster according to the present invention is shown. Like the clutch adjuster ofFIGS. 2 and 3, the clutch adjuster20includes a bracket24with two L-shaped arms24abounding a central depressed region24b. Two bolts14secure the bracket24to the cover12. The central area24bincludes an aperture that captures the central bolt92that carries the rotary gear25, the teeth of the gear25being configured to engage the clutch adjusting ring15. As can be seen fromFIG. 5, the spacing between the head93of the bolt92and the rotary gear25is such that substantially no axial movement of the bolt92is permitted with respect to the bracket24.

In keeping with this embodiment of the invention, a locking and adjusting member90is provided that overlies the head93of the bolt92and is moveable axially with respect to the bolt between a locking position (shown inFIG. 5) and an adjusting position. The locking and adjusting member90includes a socket95shaped to engage the head93of the bolt92and a head98, preferably hex-shaped, adapted to be engaged by a wrench for rotating the member90and, consequently, the bolt92. The socket95is preferably in engagement with the head93of the bolt92throughout its range of axial movement. The locking and adjusting member90includes a shoulder99between its head98and socket95that is shaped to be engaged by opposed locking arms94athat are attached (by e.g., welding) to bracket arms24aand extend partially across the central depressed area24bof the bracket. As illustrated, the shoulder99has a square shape (when viewed from above as inFIG. 4) thus presenting four facets, but may be of other polygonal shapes (e.g. hexagonal or octagonal) as long as the facets of the shoulder present a sufficient contact area with respect to the edges of the locking arms94ato prevent the shoulder from being stripped when a torque is applied to the locking and adjusting member90in the locking position. A spring96is provided to bias the locking and adjusting member90toward the locked position. As illustrated, the spring96is positioned between the head of the bolt92and the top wall of the socket95, with the spring96seated in a recess in the head93of the bolt90. Alternatively, the spring94can be seated around the head93of the bolt92between the central area24bof the bracket24and the bottom side of the locking and adjusting member90.

Consequently, if a clutch to which the clutch adjuster ofFIGS. 4 and 5is attached requires adjustment, a socket wrench is used to engage the head98of the locking and adjusting member90. The wrench is pushed down against the force of the spring96to move the locking and adjusting member90toward the head93of the bolt92until the shoulder99is located below the lower edges of the locking arms94a. In this position, a member90will be free to rotate upon rotation of the wrench, thus making clutch adjustment possible. When proper adjustment is achieved, and the adjusting member90is oriented so that the opposed edges of the shoulders99are aligned with the edges of the locking arms94a. Thus, when the locking member90is biased upwardly by the force of the spring96, the shoulders99are aligned with and engaged by the locking arms94ato prevent rotation of the locking member, which, in turn, prevents rotation of the bolt92.

Turning toFIGS. 6 and 7, a third embodiment of the clutch adjuster20is shown which incorporates a removable locking member40. Like locking member22, locking member40has a central recessed portion40bbetween two opposed raised portions40awhich are configured to engage two sides of the shaped head52of the center bolt50when in its locking position. However, instead of being placed under the head52, the locking member40is placed over the shaped head52of the center bolt50, and is secured in the locking position to the head of the bolt50by a threaded fastener, such as screw53. A retaining washer54is secured to the shaft of the screw53between the lock40and the head52. Thus, the retaining washer54maintains the locking member40on the screw53, while permitting the locking member40to rotate with respect to the screw53. The center bolt50is secured to the sprocket25. When in the locking position, the center bolt shaped head52and the locking member40resides substantially in the central portion of strap24between the two L-shaped arms24a, thus preventing both the lock and the center bolt from rotating. By removing the lock assembly (locking member40, screw53, retaining washer54), access to the center bolt is gained and adjustment of the clutch can be achieved. The clutch adjustment can be performed with a socket wrench, as set forth above. When the lock assembly is reattached, a visual check can be made to insure that locking has been accomplished.

As can be appreciated, in none of the embodiments is there any axial movement of the sprocket25or center bolt30. This insures more reliable operation of the clutch adjuster.

Those skilled in the art will appreciate that there are slight variations which will work equally as well as the one presented. Although the invention has been described in terms of certain preferred embodiments, the invention is not to be limited to the same. Instead the invention is to be defined by the scope of the following claims.