MXPA96001084A - Brake assembly for steering axle - Google Patents

Abstract

The present invention relates to a vehicle brake assembly comprising a pair of arcuate, pivotally mounted brake shoes, located inside a brake drum, each of said brake shoes having a forced cam roller for attachment direct with a S-cam rotated by an actuator shaft, the rotation of said S-cam in a first direction of rotation from a totally disengaged condition by forcing radially outwardly relative to said brake drum to at least one of said brake shoes. brake, said brake assembly further comprising: a steering knuckle disposed adjacent said brake shoes, said steering knuckle having an axle stub axle extending axially between said brake shoes and having both a top steering knuckle bushing and a lower steering pivot bushing where a steering arm is formed directly by said steering pivot bushing s upper and an extension rod arm is formed directly from said lower steering pivot bushing, at least one mounting pivot pin directly to said steering ball contacting and pivotally holding said brake shoes, a holding tube rotatably holding said actuator shaft, said support tube being attached to said steering knuckle

Description

BRAKE ASSEMBLY FOR STEERING AXLE BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering and brake joint assembly for a steering axle in a heavy or medium traffic truck. More specifically, the present invention relates to a steering and brake ball joint assembly for the steering axle in a heavy or medium traffic truck where the steering knuckle provides the direct support of the brake shoes and the activation device of the vehicle. brake without a brake spider. 2. Description of the State of the Art It is well known in the state of the art to use a "S-cam" to activate a pair of arcuate brake shoes to contact the inner surface of a brake drum in order to provide a Braking frictional force to a set of wheels of a vehicle. Although the present invention is not strictly limited to S-cam type rotary cam brakes, and could be used with several other rotary cam brake configurations, the invention is particularly advantageous when used in drum brake assemblies of internal extensible shoes with S-cam, and will be described in relation to these. An example of a typical S-cam extensible inner shoe drum brake is set forth in U.S. Patent No. 4,905,800 assigned to the assignee of the present invention and which is incorporated herein by reference. Traditionally, the brake shoes and the rest of the braking components that make up the brake assembly are mounted on what in the technique has been called "brake spider", which is fixed to the steering head and it supports the brake shoes and the S-cam drive device. It is desirable to minimize the total package of the brake assembly to facilitate its placement within the confines of the vehicle wheel, while simultaneously providing the required braking performance in extreme conditions. . It is also desirable to minimize the number of components required to provide the braking function, thus minimizing its complexity, weight and cost. In this way, the removal of the brake spider is desirable for many practical reasons. Attaching the connecting rod and the steering control lever to the traditionally-threaded steering knuckle assembly results in assembly problems with the cam-shaft assembly, a relatively high ratio of weight to force, and a significant increase in the deviation of the steering system. The relative movement that can occur with or without input from the driver results in undesirable steering inputs in the wheel set. A steering knuckle is commonly available for heavy traffic motor vehicles such as trucks, where the steering control lever and the connecting rod are mounted on the steering knuckle by a threaded portion in a locking nut. In the field of heavy traffic motor vehicles there is a need to provide a steering knuckle assembly where the connecting rod and the steering control lever are integrally formed as a unitary piece with the steering knuckle. This configuration would result in a higher ratio of force to weight, an improved mounting of the brake assembly and a more precise steering of the vehicle by improving the integrity of the connection between the connecting rod, the steering control lever and the ball joint. . An example of a similar steering head is described in U.S. Patent No. 5,219,176, the disclosure of which is incorporated herein by reference. These heavy traffic steering knuckles also employ projections with a separately mounted reindeer spider unit for connection to the brake assembly, as discussed above. SUMMARY OF THE INVENTION The present invention allows the elimination of the brake spider, thus reducing the number of components necessary to provide the vehicle's braking function., simultaneously minimizing assembly and weight requirements for improved overall vehicle performance. Also, the steering control lever and the connecting rod are cast in one piece with the steering knuckle to provide greater rigidity and integrity for a more accurate driving of the vehicle in response to the driver's orders and the lighter weight. The S-cam brake actuator and the arcuate brake shoes are mounted directly on the steering knuckle using the technique of the present invention. The brake activation method set forth herein utilizes an S-cam mounted on a drive rod that is supported and rotated in a frame of the drive rod where the rod frame is mounted directly on a steering knuckle, as opposed to the brake spider according to the prior art, thus providing the support and the drive of a pair of arched brake shoes. The arcuate brake shoes rotate on and are pivotably fixed at one end to a lower pivot pin which is also mounted directly on the steering knuckle, and at the opposite end are separated by rotation of the S-cam, thus providing support. Direct from the arched brake shoes without using a brake spider. US Pat. No. 5,219,176 discloses a one-piece steering knuckle assembly, wherein the connecting rod and the steering control lever are formed as one piece with the steering knuckle, thus providing greater rigidity and a smaller weight of the vehicle's steering system. However, direct mounting of the brake assembly directly to the steering head, as described in the present invention, is not envisioned. A condition of the present invention is to provide a compact brake assembly by eliminating the use of a brake spider to hold the brake components. Another condition of the present invention is to provide a compact brake assembly where the drive shaft frame is mounted directly on the steering knuckle. Another condition of the present invention is to provide a compact brake assembly where the drive shaft frame is mounted directly on a brake ball and a lower pivot pin is also mounted directly on a steering ball joint. Another additional condition of the present invention is to provide a brake assembly having a reduced number of parts using drive means supported by a steering ball to cause expansion of a pair of rotating arcuate brake shoes and supported by a lower pivot pin which is also directly attached to the steering head. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a plan view of the internal part of a drum brake assembly of extendable inner shoes with S-cam and a one-piece steering knuckle according to the present invention.; Figure 2 is a plan view of the outer part of a drum brake assembly of extendable inner shoes with S-cam and a one-piece steering knuckle according to the present invention; Figure 3 is a front cross-sectional view of the S-cam brake and steering knuckle assembly according to the present invention, taken along the line III-III of Figure 2; Figure 4 is a front plan view of the one-piece steering knuckle according to the present invention; and Figure 5 is a top plan view of the one-piece steering knuckle according to the present invention. Detailed Description of the Preferred Embodiment In this description, certain terminology will be used only for convenience and reference, and will not be limiting. For example, the terms "forward" and "backward" will refer to forward and backward directions of the brake assembly as it is installed in a vehicle. The terms "to the right" and "to the left" will refer to addresses in the drawings in relation to which the terminology is used. The terms "inward" and "outwardly" shall refer to directions to and from, respectively, the geometric center of the brake assembly of the present invention. The terms "up" and "down" will refer to addresses as they are taken in the drawings in relation to which the terminology is used. All the preceding terms include the normal derivatives and their equivalents. The term "brakes" as used herein includes drum-type brakes using all types of drive methods. Referring now to Figures 1 and 2, Figure 1 is a plan view of the inner side of the steering knuckle brake assembly of the present invention, while Figure 2 is a plan view of the outer side of the brake assembly. and steering ball joint according to the present invention. Figure 1 shows a set of left brake shoe 4A and a set of right brake shoe 4B mounted directly to a steering head 5 without the use of the brake spider traditionally used to mount a brake assembly to a steering head . The left brake shoe assembly 4A comprises a left inner core 10A which, in conjunction with a left outer core 12A, are attached to and hold the left brake plate 14A. The left brake plate 14A provides support for the upper left brake shoe 16A and the lower left brake shoe 18A which, when considered as a unit, comprises the left brake shoe assembly 4A. Similarly, the right brake shoe assembly 4B comprises a right inner core 10B which acts in conjunction with a right outer core 12B to support the left brake plate 14B. Attached to the right brake plate 14B is the upper right brake shoe 16B and the lower right brake shoe 18B which together constitute the right brake shoe assembly 4B. The cam at S 20 is rotated by the axial movement of a driving rod 70 from an actuator 74 which is commonly activated by air pressure in the application on a heavy traffic truck. The drive rod 70 is coupled by an articulation bolt 80 to a lever 72 which in turn is coupled to a drive shaft 40 attached to and rotates with the cam at S 20. Thus, the supply of a pressure signal to the actuator 74 causes the drive rod 70 to extend axially, causing the drive shaft 40 to be rotated by the lever 72. A support 76 is used to hold the actuator 74 and is attached to the steering ball joint 5 by welding and other appropriate means of union. The rotation of the cam at S 20 causes the left brake shoe assembly 4A to increase the separation distance of the right brake shoe assembly 4B, causing them to come into contact with the brake drum (not shown) and resulting in a frictional-nal interaction with the drum. Brake shoe upper left 16A, the upper right brake shoe 16B, the lower left brake shoe 18A and the lower right brake shoe 18B come into contact with the inner surface of the brake drum, thus resulting in a braking action of the rotation of a linked vehicle wheel to the brake drum. The left brake shoe assembly 4A and the right brake shoe assembly 4B are supported directly on the steering knuckle 5 by a pivot pin 34 at one end and a left roller 22A and a right roller 22B at one end opposite. In an alternative embodiment, the pivot pin 34 can be divided into two pivot pins, one for each respective brake shoe assembly. The S-cam contacts the left roller 22A and the right roller 22B, causing the left brake shoe assembly 4A and the right brake shoe assembly 4B to move further apart as the S-cam is rotated. 20. The left roller 22A engages the inner core 10A and the outer core 12A and the right roller 22B engages the right inner core 10B and the right outer core 12B. The movement of the right and left rollers 22A and 22B causes a separation of the right and left brake shoe assemblies 4B and 4A, where both the left brake shoe assembly 4A and the right brake shoe assembly 4B rotate on the pivot end 34. A reactive spring 32 is attached to the left brake shoe assembly 4A to the left of the reactive spring pin 28B. The reactive spring 32 presses the left brake shoe assembly 4A towards the right brake shoe assembly 4B, thereby reducing the overall external diameter of the brake assembly 2 to prevent contact with the brake drum when an action of the brake is not desired. braking. The steering knuckle 5 is usually made using a well-known casting method, which results in the formation of a stub 48 extending outwardly to support the wheel and the brake drum. In the present invention, a steering lever 66 is formed in one piece with the steering knuckle 5, extending from an upper steering knuckle hub 62 having an upper steering pivot guide 64 formed therein, and A steering control lever connecting bushing 68 is formed at the opposite end of a steering control lever 66 which provides the linkage to the steering linkage (not shown). In axial alignment with the upper steering pivot bushing 62 is a steering pivot guide 54 formed as one piece with the steering knuckle 5. A connecting rod 56 having a union bushing 58 is also formed as one piece with the steering knuckle 5. The rod joint bushing 58 is formed at an end remote from the connecting rod 56 for attachment to a steering rod (not shown). The manufacture of the steering ball joint 5 including as a casting a steering control lever 66 and a connecting rod 56 provides exceptional stability and rigidity for attachment to the steering joint for the purposes of precise control of positioning of the vehicle's wheel. Also extending directly from the steering knuckle 5 are the pivot pin 34 and the support tube 38, thereby providing the drive shaft bracket 40 attached to the S-cam 20. Thus, according to the present invention, no there is a need for a brake spider according to the prior art, thereby reducing the number of parts, cost and complexity. Traditionally, the brake spider is screwed to the steering knuckle 5 and provides support for the right and left brake shoe assemblies 4B and 4A on it. Now with specific reference to Figure 2, a plan view of the inner part of the brake assembly 2 and the steering knuckle 5 of the present invention more clearly illustrates the function of the reactive spring 32. The reactive spring 32 is attached to the assembly of 4A brake shoe on the left with the left reactive spring pin 28A and on one end opposite the right brake shoe assembly 4B on the right reactive spring pin 28B, thereby slightly extending the free length of the reactive spring 32. The reactive spring 32 provides for the loading of the left and right rollers 22A and 22B respectively against the S-cam 20. The retaining spring 30 is used to maintain contact between the pivot pin 34 and the left outer core 12A and the right outer core 12B of the left brake shoe assembly 4A, and analogously to maintain contact between the inner core 10A and the right inner core 10B of the right brake shoe assembly 4B against the pivot pin 34. The retaining spring 30 is connected to the left brake shoe assembly 4A on the left spring pin 26A and the right brake shoe assembly 4B on the right spring pin 26B.

Referring now to Figure 3 of the drawings, a cross-sectional view of the brake assembly 2 and steering knuckle 5 of the present invention taken along the line III-III of Figure 2 is shown. The drive shaft 40 is held within the holding tube 38, the latter being non-rotatably connected to the steering knuckle 5 by pressure, welding or other appropriate means of attachment. In an alternative embodiment, a bushing is formed inside the steering knuckle 5 surrounded and providing support to the drive shaft 40, thus eliminating the need for the holding tube 38. The holding tube 38 is pressed or retained from some other in an opening formed in the steering knuckle 5 during the manufacturing process. Similarly, the pivot pin 34 is pressed or retained in some other way in the steering knuckle 5 to provide an appropriate location and support for the left brake shoe assembly 4A and the right brake shoe assembly 4B, in FIG. very similar to the traditional way when using a brake spider. In the prior art, the support tube 38 and the pivot pin 34 will have been firmly fastened to a brake spider which, in turn, would be bolted directly to the steering head 5. With the use of the present invention, it is deleted The brake spider and the support tube 38 and the pivot pin 34 are fastened directly to the steering head, thereby reducing cost, complexity, weight and assembly requirements. The rotation of the cam on S 20 against the left roller 22A causes the left brake shoe assembly 4A to be displaced against the force of the reactive spring 32. One end of the reactive spring 32 is attached to the left reactive spring pin 28A, which it is supported by the left outer core 12A and the left inner core 10A of the left brake shoe assembly 4A. Similarly, the other end of the reactive spring 22 is attached to the right reactive spring pin 28B, which is supported by the right outer core 12B and the right inner core 10B of the right brake shoe assembly 4B. The retaining spring 30 holds the right and left brake shoe assemblies 4B and 4A in position on the pivot pin 34. The pivot pin 34 which is attached to the steering knuckle 5 and holds the assembly is more clearly shown. of left brake shoe 4A in the left inner core 10A and the left outer core 12A. The left brake shoe assembly 4A is held in position on the pivot pin 34 with a retaining clip 42 and a retaining collar 44. The retaining clip 42 may be a variety of common staple designs such as " circlip "(circular staple). The retaining collar 44 can be made from a type of elastic material that provides the frictional damping of the left brake shoe assembly 4A to prevent or reduce the squealing level of the brakes. Although not shown in Figure 3, the right brake shoe assembly is maintained on the pivot pin in an identical manner. Also shown is the stub 48 which extends and is formed from the steering knuckle 5, on which the bearings of the brake drum are guided. The steering pivot bushing 52, which has an extension rod 56 extending therefrom, is also shown in one piece with the steering knuckle 5. Referring now to Figure 4, a front view of the steering knuckle 5 according to the present invention is shown with the steering control levers 66 and the extension rods 56 form a part respectively with the upper steering pivot bushing 62. and the lower steering pivot bushing 52. Thus, the steering knuckle 5, as shown in Fig. 4, is made of a one-piece forging, with the following machining operations to form the stub 48, the lower steering pivot guide 54 and the upper steering pivot guide 64. Also, the rod attachment bushing 58 and the steering control lever connecting bushing 68 are formed and pierced for subsequent assembly of a steering control lever and an extension rod. The cut lines show the openings for the support tube 38 and the pivot pin 34. Figure 5 is a top plan view of the steering knuckle according to the present invention, as shown in Figure 4, illustrating with more clearly the configuration of the connecting rod 56 and the steering control lever 66 respectively connected to the upper steering pivot bushing 62 and the lower steering hub 52. While the steering control lever 66 and the extension rod 56 are shown as certain geometric positions with respect to the steering knuckle 5 and the stub 48, it is obvious that various shapes and angles can be adopted with respect thereto. There may also or may not be a connecting rod. In general, the present invention provides a one-piece steering knuckle assembly for commercial heavy vehicles, such as trucks, constructed and arranged to receive and activate a brake shoe assembly without the use of a brake spider. A wheel spindle extends from the ball joint to support a brake drum and wheel. An extension rod and a steering control lever are formed with the steering ball joint as a one-piece forging. The steering knuckle is formed, according to the present invention, as a piece including a top and bottom steering pivot bushing, an extension rod and a steering control lever. In this way, the steering knuckle and the extension rod and the steering control lever are especially rigid, thus producing precise control of the angle of the wheel during the driving of a heavy traffic truck. The preferred metal in the steel used to forge billet in the unitary steering knuckle. Although this invention has been described in its preferred form and with a certain degree of detail, it is understood that the present description of the preferred embodiments have been made only by way of example, and that many changes in the construction can be resorted to, combination and arrangement of the parties without departing from the spirit and scope of this invention, according to the claims that follow.

Claims (14)

1. CLAIMS 1. A vehicle brake assembly of the type comprising a pair of rotatably mounted arcuate brake shoes, located inside a brake drum, each of said brake shoes having a cam roll forced to a direct gear with an S-cam rotated by a drive shaft, the rotation of said S-cam in a first direction of rotation from a fully disengaged condition forcing radially outwardly relative to said brake drum to at least one of said brake shoes. brake, said brake assembly further comprising: a steering knuckle disposed adjacent said brake shoes, said steering knuckle having a shaft spindle extending axially between brake shoes; at least one mounting pivot pin directly to said steering ball contacting and pivotably holding said brake shoes; a holding tube rotatably holding said driving shaft, said holding tube being attached to said steering ball. The vehicle brake assembly of claim 1, wherein said pivot pin has a tapered section engaging a corresponding tapered section formed in said steering ball joint. 3. The vehicle brake assembly of claim 1, further comprising a retaining ring surrounding said pivot pin and disposed adjacent a brake core section of each of said brake shoes, said retaining ring preventing a substantial axial movement of said brake shoes. The vehicle brake assembly of claim 3, wherein said retaining ring engages a circumferential retaining groove formed in said pivot pin. The vehicle brake assembly of claim 1, wherein a retaining device is provided on said pivot pin adjacent said brake webs to prevent axial movement of said brake shoes. 6. A brake assembly for the steering axle of a vehicle comprises: a steering knuckle having an axle stub axle extending therefrom to hold and steer a vehicle; at least one pivot pin attached to said steering ball joint; a pair of arcuate brake shoes having first and second ends, said first ends being pivotably supported on said pivot pin; a pair of roller pushers rotatably supported by said second ends of said brake shoes; an S-cam rotated by a drive shaft supported by a drive support tube, wherein said support tube is fixed to said steering ball joint, said S-cam being arranged to come into contact with said roller pushers; wherein said cam in S is rotated by said drive shaft and driven to engage said roller pushers, thereby forcing at least one of said brake shoes to pivot on said pivot pin and thus move radially outwardly to engage frictionally with a brake drum. The brake assembly of claim 6, wherein said lower pivot pin has a tapered section engaging a matching tapered section formed in said steering ball joint. The brake assembly of claim 6, further comprising a retaining ring engaging said lower pivot pin and coming into contact with said first ends of said brake shoes, thereby retaining said brake shoes on said pivot pin. The brake assembly of claim 8, wherein said retaining ring engages a circumferential retaining groove formed in said pivot pin. 10. The brake assembly of claim 6, wherein a retaining device is attached to said pivot pin adjacent said brake shoes for retaining said brake shoes on said pivot pin. 11. A brake shoe assembly having a pair of arcuate brake shoes supported on said S-cam at one end and supported by one or more pivot pins at an opposite end and a rotary drive shaft in a holding tube. said driving shaft having a S-cam attached to a first end and a driving lever to a second end; a reactive spring having one end attached to a second end of said brake shoes toward each other and the steering knuckle having a top steering pivot bushing directly attached to the steering knuckle and a lower steering pivot bushing attached directly to the steering knuckle and aligned with said upper steering pivot bushing; and a steering control lever formed directly from said upper steering pivot bushing and an extension rod formed directly from said lower steering pivot bushing; and a stub formed from said steering ball joint, axially extending to rotatably hold a brake drum for a heavy traffic truck, the improvement comprising: said holding tube attached to said steering ball and passing through an aperture formed therein. steering ball joint; and said pivot pin attached to the steering knuckle radially opposite said holding tube. The steering shoe and brake shoe assembly of claim 11, further comprising a rotational drive shaft in said support tube, said drive shaft having a S-cam attached to a first end and a drive lever to a second end; a reactive spring having one end attached to said brake shoes and a second end joined to the second end of said brake shoes, so as to force said pair of brake shoes toward each other; an actuator having a drive rod attached to said drive lever to cause said drive shaft to rotate, thereby causing the S-cam to separate said roller pushers and said brake shoes. 13. A vehicle brake assembly of the type comprising a pair of rotatably mounted arcuate brake shoes, located within a brake drum, each of said brake shoes having a cam roll forced to a direct engagement with a S-cam rotated by a drive shaft, the rotation of said S-cam in a first direction of rotation from the fully disengaged condition forcing radially outwardly relative to said brake drum to at least one of said brake shoes , said brake assembly further comprising: a steering knuckle disposed adjacent said brake shoes, said steering knuckle having a shaft stub axle extending axially between said brake shoes; at least one pivot pin mounted directly to said steering ball contacting and pivotably holding said brake shoes; a support bushing rotatably holding said drive shaft, said bushing extending from said steering ball. The vehicle brake assembly of claim 13, further comprising joining means for axially maintaining said brake shoe on said pivot pin.