CA1305078C - Brake cam shaft attachment assembly - Google Patents
Brake cam shaft attachment assemblyInfo
- Publication number
- CA1305078C CA1305078C CA000555543A CA555543A CA1305078C CA 1305078 C CA1305078 C CA 1305078C CA 000555543 A CA000555543 A CA 000555543A CA 555543 A CA555543 A CA 555543A CA 1305078 C CA1305078 C CA 1305078C
- Authority
- CA
- Canada
- Prior art keywords
- shaft
- slack adjuster
- circlip
- attachment assembly
- assembly
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Landscapes
- Braking Arrangements (AREA)
Abstract
ABSTRACT
There is disclosed an assembly for attaching a brake cam shaft to a slack adjuster. The assembly has a cam shaft with cam elements at one end thereof and an attachment portion at its other end. The shaft has a spline adjacent the attachment portion. A securing member is locatable about the shaft or a shoulder on the shaft, the securing member or shoulder limits the extent to which the splined end of the shaft may project into or through the splined aperture of the slack adjuster. Fastening means is secured to the attachment portion such that when the shaft is secured to the slack adjuster, the shaft is held fast relative thereto with the slack adjuster located between the shoulder or the securing member and the fastening means.
There is disclosed an assembly for attaching a brake cam shaft to a slack adjuster. The assembly has a cam shaft with cam elements at one end thereof and an attachment portion at its other end. The shaft has a spline adjacent the attachment portion. A securing member is locatable about the shaft or a shoulder on the shaft, the securing member or shoulder limits the extent to which the splined end of the shaft may project into or through the splined aperture of the slack adjuster. Fastening means is secured to the attachment portion such that when the shaft is secured to the slack adjuster, the shaft is held fast relative thereto with the slack adjuster located between the shoulder or the securing member and the fastening means.
Description
~ -2-~3~
The invention relates to an assembly for attaching a brake cam shaft to a slack adjuster.
Vehicle brakes in relation to which the present invention may be used usually comprise a brake drum, two opposed brake shoes either pivotally secured at one end to each other or to a brake spider and a cam shaft having a cam member or element at one end and a spline coupling at the other end. The cam element is operative to engage brake rollers secured to the other ends of the shoes and these other ends are normally biassed towards each other and against the cam element whereby upon rotation of the cam shaft the rollers are caused to ride over the cam element to thereby expand the shoes and bring them into contact with the brake drum to effect a braking action. In vehicles and in particular in heavy vehicles the cam shaft is rotated by a slack adjuster which is mounted relative to the splined end of the shaft and itself has a complementary splined aperture. Pivotal movement is achieved by securing the distal end of the slack adjuster to a piston rod of an air 2~ chamber via a clevis memher. Pressurization of the air chamber causes the piston rod to extend from the chamber and this piston rod is coupled to the clevis member. This extension or stroke of the piston rod pivots the slack adjuster and in turn rotates the cam shaft. The purpose of slack adjusters is well known. Such slack adjusters are designed and used to remove any slack from the brake caused by wear of the brake shoes.
13~
Traditionally, the splined end of the cam shaft was formed with a groove for receiving a circlip. The circlip receiving groove was located adjacent the end of the shaft at which the spline was formed. The shaft was assembled and positioned relative to the slack adjuster by engaging the spline of the shaft with the internal spline of the slack adjuster. Upon engagement and proper positioning of the cam elements of the shaft the circlip was then positioned relative to the shaft. The circlip served only to inhibit longltudinal movement of the shaft in one direction, that is, away from the cam elements. Relative movement of the shaft and slack adjuster was otherwise possible in the longitudinal direction whilst the splines were in engagement. The extent of the movement depended upon play between the clevis member and the distal end of the slack adjuster as well as on any clearance between these two splines. If the freedom of movement of the cam shaft was excessive then this led to undue wear of the spline and in some instances damage to the vehicle brake and possibly to the axles about which the brake drums were mounted. In addition, this circlip type connection tended to damage the side plate of the slac~ adjuster.
It is an object of the present invention to provide a brake cam shaft attachment assembly which at least minimises some of the disadvantages referred to above.
According to one aspect of the invention there is ~ provided a brake cam shaft attachment assembly for attaching ; ~: : : :
S07~3 ~ 4 --a brake cam shaft relative to a slack adjuster, the slack adjuster having an opening therethrough with a spline formed therein, said assembly including the cam shaft having cam elements at one end thereof and a threaded attachment portion at the other end thereof, a spline on said shaft adjacent said attachment portion, a circlip locatable about and to the shaft at a location spaced from the one end, said circlip lîmiting the extent to which the splined end of the shaft projects into the splined aperture of the slack adjuster, a washer locatable about the other end and a threaded fastening means securable to said attachment portion at the other end whereby, when said shaft is secured relative to the slack adjuster, the shaft is locked fast to the slack adjuster to prevent relative longitudinal movement with the latter located on the shaft and between said circlip and said washer with the washer clamped against a side face of the spline of the slack adjuster by said ~astening means.
Preferably the circlip is attachable to the shaft and the assembly includes a spacer locatable on the shaft circlip and the slack ad3uster.
A particular preferred embodiment is illustrated in the drawing which shows an exploded perspective view of an assembly according to the inventi~n.
The assembly 10 includes a cam shaft 11. Sha$t 11 has cam members 12 and 13 integrally formed at one end thereof~ Cam members 12 and 13 cooperate with brake shoe rollers and ensure that the shoes are biassed apart upon ' ~3~Q78 rotation of the shaft 11. The other end of the shaft is formed with a reduced diameter threaded attachment portion 14. Adjacent portion 14 the shaft is provided with a spline 15. The shaft 11 has zones 16 and 17 which may 'oe journalled relative to bearings or bushes Inot shown) to mount the shaft 11 for rotation. Spacer washer 18 ensures that the bearing or bush which locates about shaft portion 17 does not engage or interfer with circlip 19. Circlip 19 is received within circlip groove 20 and this groove locates the circlip at a point spaced from the end of the shaft at ; which the threaded attachment portion 14 is located. A
further spacer washex 21 is located on the opposite side of circlip 19 to that at which spacer washer 18 is located.
The slack adjuster 25 may be coupled to an air 5 chamber (not shown) via a clevis member (not shown). The clevis member may be secuxed to a select one of apertures 26, 27 and 28 which are located at the free end of the slack adjuster. The slack adjuster 15 has a through ~ore formed with a spline 29. The spline 29 has end faces 30 only one 10 of which is visible in the exploded view of the drawings. A
circumferential raised portion 31 extends around each end face 30 of the spline of the slack adjuster. The face of the slac~ adjuster (not visible~ is constructed in a similar fashion~ Spacer washer 21 locates against spline face 30 on 15 the adjacent side of the slack adjuster whereas washer 32 locates within raised portion 31 and against face 30 of the side of the slack adjuster 25 visible in the drawing. Lock nut 33 has an integrally formed locking ring 34.
, "~.
,~,..
To assemble the arrangement shown in the drawing spline 15 is brought into engagement with spline 29 and in this way threaded attachment portion 14 projects through the opening in the slack adjuster. Spacer washer 18 locates around the shaft 11 and cannot move towards the end of the shaft having the threaded portion 14 because ~irclip 19 locates in groove 20. Circlip 19 cannot contact the spline face 30 on the other side of the slack adjuster because the spacer washer 21 is interposed. Once por ion 14 projects through the opening in the slack adjuster washer 32 is positioned over portion 14 and the lock nut 33 is threaded onto portion 14 until washer 32 is pressed against iace 30.
Thus, with the lock nut 33 tightened in the manner described above the slack adjuster 25 is securely held between circlip 19 and washer 32 with spacer washer 20 interposed between it and the circlip. In this way the shaft 11 is securely locked relative to the slack adjustex and cannot move longitudinally in either dire~tion.
The assembly of the invention relative longitudinal movement between the cam shaft and the slack adjuster is eliminated and damage or wear between the splines which may be caused by.longitudinal relative movement between the shaft and the slack adjuster does not occur.
, f ~
',' ,~,., - : ' '
The invention relates to an assembly for attaching a brake cam shaft to a slack adjuster.
Vehicle brakes in relation to which the present invention may be used usually comprise a brake drum, two opposed brake shoes either pivotally secured at one end to each other or to a brake spider and a cam shaft having a cam member or element at one end and a spline coupling at the other end. The cam element is operative to engage brake rollers secured to the other ends of the shoes and these other ends are normally biassed towards each other and against the cam element whereby upon rotation of the cam shaft the rollers are caused to ride over the cam element to thereby expand the shoes and bring them into contact with the brake drum to effect a braking action. In vehicles and in particular in heavy vehicles the cam shaft is rotated by a slack adjuster which is mounted relative to the splined end of the shaft and itself has a complementary splined aperture. Pivotal movement is achieved by securing the distal end of the slack adjuster to a piston rod of an air 2~ chamber via a clevis memher. Pressurization of the air chamber causes the piston rod to extend from the chamber and this piston rod is coupled to the clevis member. This extension or stroke of the piston rod pivots the slack adjuster and in turn rotates the cam shaft. The purpose of slack adjusters is well known. Such slack adjusters are designed and used to remove any slack from the brake caused by wear of the brake shoes.
13~
Traditionally, the splined end of the cam shaft was formed with a groove for receiving a circlip. The circlip receiving groove was located adjacent the end of the shaft at which the spline was formed. The shaft was assembled and positioned relative to the slack adjuster by engaging the spline of the shaft with the internal spline of the slack adjuster. Upon engagement and proper positioning of the cam elements of the shaft the circlip was then positioned relative to the shaft. The circlip served only to inhibit longltudinal movement of the shaft in one direction, that is, away from the cam elements. Relative movement of the shaft and slack adjuster was otherwise possible in the longitudinal direction whilst the splines were in engagement. The extent of the movement depended upon play between the clevis member and the distal end of the slack adjuster as well as on any clearance between these two splines. If the freedom of movement of the cam shaft was excessive then this led to undue wear of the spline and in some instances damage to the vehicle brake and possibly to the axles about which the brake drums were mounted. In addition, this circlip type connection tended to damage the side plate of the slac~ adjuster.
It is an object of the present invention to provide a brake cam shaft attachment assembly which at least minimises some of the disadvantages referred to above.
According to one aspect of the invention there is ~ provided a brake cam shaft attachment assembly for attaching ; ~: : : :
S07~3 ~ 4 --a brake cam shaft relative to a slack adjuster, the slack adjuster having an opening therethrough with a spline formed therein, said assembly including the cam shaft having cam elements at one end thereof and a threaded attachment portion at the other end thereof, a spline on said shaft adjacent said attachment portion, a circlip locatable about and to the shaft at a location spaced from the one end, said circlip lîmiting the extent to which the splined end of the shaft projects into the splined aperture of the slack adjuster, a washer locatable about the other end and a threaded fastening means securable to said attachment portion at the other end whereby, when said shaft is secured relative to the slack adjuster, the shaft is locked fast to the slack adjuster to prevent relative longitudinal movement with the latter located on the shaft and between said circlip and said washer with the washer clamped against a side face of the spline of the slack adjuster by said ~astening means.
Preferably the circlip is attachable to the shaft and the assembly includes a spacer locatable on the shaft circlip and the slack ad3uster.
A particular preferred embodiment is illustrated in the drawing which shows an exploded perspective view of an assembly according to the inventi~n.
The assembly 10 includes a cam shaft 11. Sha$t 11 has cam members 12 and 13 integrally formed at one end thereof~ Cam members 12 and 13 cooperate with brake shoe rollers and ensure that the shoes are biassed apart upon ' ~3~Q78 rotation of the shaft 11. The other end of the shaft is formed with a reduced diameter threaded attachment portion 14. Adjacent portion 14 the shaft is provided with a spline 15. The shaft 11 has zones 16 and 17 which may 'oe journalled relative to bearings or bushes Inot shown) to mount the shaft 11 for rotation. Spacer washer 18 ensures that the bearing or bush which locates about shaft portion 17 does not engage or interfer with circlip 19. Circlip 19 is received within circlip groove 20 and this groove locates the circlip at a point spaced from the end of the shaft at ; which the threaded attachment portion 14 is located. A
further spacer washex 21 is located on the opposite side of circlip 19 to that at which spacer washer 18 is located.
The slack adjuster 25 may be coupled to an air 5 chamber (not shown) via a clevis member (not shown). The clevis member may be secuxed to a select one of apertures 26, 27 and 28 which are located at the free end of the slack adjuster. The slack adjuster 15 has a through ~ore formed with a spline 29. The spline 29 has end faces 30 only one 10 of which is visible in the exploded view of the drawings. A
circumferential raised portion 31 extends around each end face 30 of the spline of the slack adjuster. The face of the slac~ adjuster (not visible~ is constructed in a similar fashion~ Spacer washer 21 locates against spline face 30 on 15 the adjacent side of the slack adjuster whereas washer 32 locates within raised portion 31 and against face 30 of the side of the slack adjuster 25 visible in the drawing. Lock nut 33 has an integrally formed locking ring 34.
, "~.
,~,..
To assemble the arrangement shown in the drawing spline 15 is brought into engagement with spline 29 and in this way threaded attachment portion 14 projects through the opening in the slack adjuster. Spacer washer 18 locates around the shaft 11 and cannot move towards the end of the shaft having the threaded portion 14 because ~irclip 19 locates in groove 20. Circlip 19 cannot contact the spline face 30 on the other side of the slack adjuster because the spacer washer 21 is interposed. Once por ion 14 projects through the opening in the slack adjuster washer 32 is positioned over portion 14 and the lock nut 33 is threaded onto portion 14 until washer 32 is pressed against iace 30.
Thus, with the lock nut 33 tightened in the manner described above the slack adjuster 25 is securely held between circlip 19 and washer 32 with spacer washer 20 interposed between it and the circlip. In this way the shaft 11 is securely locked relative to the slack adjustex and cannot move longitudinally in either dire~tion.
The assembly of the invention relative longitudinal movement between the cam shaft and the slack adjuster is eliminated and damage or wear between the splines which may be caused by.longitudinal relative movement between the shaft and the slack adjuster does not occur.
, f ~
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Claims (9)
1. A brake cam shaft attachment assembly for attaching a brake cam shaft relative to a slack adjuster, the slack adjuster having an opening therethrough with a spline formed therein, said assembly including the cam shaft having cam elements at one end thereof and a threaded attachment portion at the other end thereof, a spline on said shaft adjacent said attachment portion, a circlip locatable about and to the shaft at a location spaced from the one end, said circlip limiting the extent to which the splined end of the shaft projects into the splined aperture of the slack adjuster, a washer locatable about the other end and a threaded fastening means securable to said attachment portion at the other end whereby, when said shaft is secured relative to the slack adjuster, the shaft is locked fast to the slack adjuster to prevent relative longitudinal movement with the latter located on the shaft and between said circlip and said washer with the washer clamped against a side face of the spline of the slack adjuster by said fastening means.
2. The attachment assembly of claim 1 wherein the circlip is attachable to the shaft.
3. The attachment assembly of claim 2 including a spacer locatable on the shaft circlip and the slack adjuster.
4. The attachment assembly of claim 1 including a spacer locatable on the shaft between the circlip and the slack adjuster.
5. The attachment assembly of claim 4, wherein said shaft is journalled for rotation relative to bushes and the assembly includes a further spacer locatable on the shaft between one of the bushes and the circlip.
6. The attachment assembly of claim 1 wherein said fastening means comprises a lock nut.
7. The attachment assembly of claim 1, wherein the attachment portion comprises a screw threaded extension to the shaft and the fastening means comprises a threaded nut engageable with the extension.
8. The attachment assembly of claim 7 wherein the circlip is permanently securedto the shaft.
9. The attachment assembly of claim 7 including a spacer locatable on the shaft between the circlip and the slack adjuster.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000555543A CA1305078C (en) | 1987-12-29 | 1987-12-29 | Brake cam shaft attachment assembly |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000555543A CA1305078C (en) | 1987-12-29 | 1987-12-29 | Brake cam shaft attachment assembly |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1305078C true CA1305078C (en) | 1992-07-14 |
Family
ID=4137167
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000555543A Expired - Fee Related CA1305078C (en) | 1987-12-29 | 1987-12-29 | Brake cam shaft attachment assembly |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1305078C (en) |
-
1987
- 1987-12-29 CA CA000555543A patent/CA1305078C/en not_active Expired - Fee Related
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |