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Title:
BRAKE LINING WEAR INDICATOR GAUGE
Document Type and Number:
WIPO Patent Application WO/1993/020365
Kind Code:
A1
Abstract:
A one piece brake lining wear indicator gauge (1) is a reversible circular flat device, with calibration marks on both of the flat surfaces of the dial which when the device is fastened to the splined end of a rotatable brake shoe camshaft (5) equipped with manual or automatic slack adjusting levers the device becomes the means for disclosing the amount of brake lining wear that takes place inside a brake drum compartment.

Inventors:
Prince
Robert
John
Application Number:
PCT/CA1992/000129
Publication Date:
October 14, 1993
Filing Date:
March 27, 1992
Export Citation:
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Assignee:
Prince
Robert
John
International Classes:
F16D66/02; (IPC1-7): F16D66/02
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Claims:
The claims
1. : Having described and disclosed the aforesaid invention with it's useful purposes to both the operator and the inspection mechanic in the field of vehicle brake maintenance, with the ease of manufacturing, packaging and merchandising, I Robert John PRINCE therefore claim exclusive property rights to manufacture, to use, to sell or to grant license to manufacture, to use and to sell the following invention: A brake lining wear indicator gauge as mentioned in claim 1 of the disclosing specifications, a brake lining wear gauge inexpensive to manufacture, easy to mount on all existing braking systems using rotating brake cams activated by slack adjusting levers. A brake lining wear indicator gauge having 3 delimiting notches cut into the circumference of the wear indicator gauge for accentuating the calibration marks on the face of the dial instead of protruding tabs or flanges extend¬ ing beyond the flat surfaces of the gauge to suffer undue road hazard damages to protruding indicator tabs as mentioned in claim 2 of the specifications.
2. A brake lining wear indicator which consists of a one piece gauge axially mounted and fixed on the splined end of a rotating brake camshaft as described in claim 3 of the specification disclosure, a dial gauge storing all of the brake lining wear information on the face of a dial ready to be interpreted by the brake inspection mechanic or the vehicle operator.
3. A reversible dial gauge for the purpose of fine tuning the alighment mark F on the face of the dial gauge to an axial line formed from the center of the clevis pin hole at the top end of the brake lever to the machined centering hole in the splined end of the rotating camshaft that extends through the hub of the slack adjusting lever as set forth in claim.
4. The reversing of the dial gauge fixed on the splined end of the rotating camshaft allows for the fine tuning of the start calibration mark F on the face of the dial gauge when oversize brake linings are installed on a vehicle as explained in claim 4 of the specifications.
5. 4 I also claim a brake lining wear indicator gauge with calibration marks on the face of the dial able to read brake lining wear when a slack adjusting lever has to be adjusted from left to right or when a slack adjuster has to be adjusted from right to left. The direction of adjustments depending on the mounting position of the slack adjuster being installed on the left or the right side of a vehicle, on the front or on the rear of a vehicle as described in claim 5 of the specification disclosure.
6. I claim a brake lining wear indicator gauge with a directional alert built into the face of the dial. There are calibration marks on the dial face of the brake lining wear indicator gauge that read from left to right and there are calibrations marks on the dial face of the brake lining wear indicator gauge that read from right to left, these calibrations are placed in a descending numerical value and serve to alert and warn the apprentice mechanic when he is adjusting the brakes the wrong way, an expedient safety feature built into the gauge as an aid in the prevention of brake related life threatening accidents on the roads.
7. A seventh claim is made for the material used in the manufacturing of the brake lining wear indicator gauge. The brake lining wear indicator gauge is not singled out to be manufactured with metallic substances only, the brake lining wear indicator gauge can be manufac¬ tured from a variety of compositions and substances that can be pressed or poured in a mould. The brake lining information on the face of the dial can be stamped on, sprayed on or moulded into the dial during or after the manufacturing process of the brake lining wear indicator. AMENDED CLAIMS [received by the International Bureau on 2 February 1993 (02.02.93); original claims 16 replaced by amended claims 16 (3 pages)] 1 A brake lining wear indicator gauge as mentioned and described in the disclosing specifications, having several delimiting notches cut into the outer circumference of the dial for the purpose of accentuating the calibration marks on the face of the register, which calibration marks are used for calculating the amount of brake component wear by storing on both faces of the register the degrees of brake camshaft rotation.
8. 2 A brake lining wear indicator gauge as mentioned in claim 1, which consists of a one piece register, axially mounted and fixed to the splined end of a rotating brake camshaft so that the dial gauge can rotate in unison with the camshaft when rotation due to brake adjustments are made.
9. 3 A brake lining wear indicator gauge as mentioned in claim 1, and claim 2, comprising of a circular register with the same information numbers and calibration marks on the both faces of the register, having an alignment mark on the face of the dial to indicate the start of the brake adjustment cycle, the said alignment mark being offset with the splined notches in the center of the register for the purpose of changing and timing the start position of the pointer when the register is reversed, enabling to alter the timing of the dial, gauge to the brake camshaft when over size brake linings are installed. 4: A brake lining wear indicator gauge as mentioned in claim 3, with calibration marks and numbers put on both sides of the dial register, having on both sides of the dial gauge two sets of the same numbers decreasing in numerical value from the starting pointer for the purpose of reading brake cam rotation in either direction of the brake cam rotation.
10. 5 A brake lining wear indicator gauge as mentioned in claim 4, with the numbers on both sides dial gauge arranged in descending numerical value starting from the start indicator pointer for the purpose of adjustment directional alert when brake adjustments are made, having finer calibration marks between the numbers that are on both side of the dial face for calibrating and recording degrees of brake camshaft rotation, making this gauge, a reversible brake lining wear indicator gauge. 6: A claim is made for materials used in the manufacturing of the brake lining wear indicator gauge, which substances used in the manufacturing of the brake lining wear indicator gauge range from metallic substances, non ferrous alloys and a variety of compositions and substances that can be poured in a mould, so that the information on the face of the dial register can be stamped on the face of the dial, sprayed on or moulded into the face of the dial during or after the manufacturing process of the brake lining wear indicator gauge.
Description:
BRAKE LINING WEAR INDICATOR GAUGE

Specifications and Disclosure of:

In vehicle braking mechanisms of the type using a cam positioned between two brake shoes and activated by a rotatable camshaft, it is common practice to accomplish movement of the cam by attaching to the cam a motor driven actuating lever. Because of the limitations of the engine power stroke activating the lever rotating the brake cam a compensating device was built into the lever to make up for the brake lining wear taking place inside the brake drum compartment. These types of levers are known as slack adjusting levers, which can be manually or automatically adjusted. As the brake lining wears out inside the brake drum compartment a compensating adjustment is made on the slack adjusting lever outside the brake drum compartment. The method of compensating adjustment is done by rotating the brake camshaft inside the hub of the slack adjusting lever. The accumulated amount of rotational adjustments made inside the hub of the slack adjusting lever causing a differential between the cam and the lever becomes a source for accumulating brake lining wear data.

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When brake linings wear out compensating adjustments becomes essential in order to minimize the amount of travel the adjustable lever needs to travel in order to apply the brakes. The purpose of the wear indicator dial gauge is to indicate the amount of compensating adjustment that has taken place during each of the slack adjustments made by comparing the calibration marks on the brake lining wear indicator gauge with the alignment mark 6 on original equipment slack adjusters or by virtue of a straight edge ruler forming an axial center line starting from the center of the clevis pin hole 11 on the slack adjusting lever to the machined centering hole on the splined end of the rotating camshaft axially mounted in the hub of the lever.

The standard procedure used by the industry for check¬ ing the amount of brake lining wear taking place inside a brake drum compartment is done by removing a brake drum, or by removing an inspection cover at the rear of the brake drum compartment or by peeking through a specially positioned inspection hole in order to get a visual assessment of the amount of brake lining wear.

It has been proposed to make this brake lining wear information externally visible in the form of a gauge in order to assist the brake service mechanic and the operator of the vehicle by showing the condition of brake linings inside a brake drum compartment without having to remove a wheel to get the same information.

As the brake camshaft rotates inside the hub of the slack adjusting lever every time brake adjustments are made to the brakes on a vehicle so the brake lining wear indicator gauge rotates with the brake camshaft by virtue of the splined contact the gauge has with the brake camshaft. The brake lining wear indicator gauge remains on the end of the brake camshaft as a visual and external reminder of the amount of adjustment travel that has taken place since the beginning of the brake adjusting cycle.

The proposed mechanisms for recording brake lining wear prior to this invention have not been without some difficulties and affected costly modifications to the existing brake mechanisms. In the case of one prior device having two co-acting members namely a stator and a rotor also called an index and a dial plate, this system proved to be mechanically uneconomical because of having to adapt to the variation in size and styles of slack adjusting levers of the manual and automatic kind, difficulty was encountered with the attaching tabs of the co-acting parts to the brake mechanism.

Other problems encountered with prior dual component co-acting brake lining wear gauges was the indicator tabs protruding from the face of the dial, these few protruding tabs being exposed to the road hazards on gravel roads were continually getting bent giving the brake service mechanic and the vehicle operator a distorted reading of the brake lining wear.

Another obstacle encountered with the kind of brake lining wear indicator gauge using a capscrew to fasten the co-acting pointer to the rotating brake camshaft was the extra cost encountered in the manufacture of brake cams and the impracticality of installing this type of a gauge on vehicles already in use in the field and on the roads.

The present invention is an improved brake lining wear indicator gauge and claims to have overcome all these aforementioned costly difficulties and maintenance problems. The present invention does not require costly modifications to the brake camshaft mechanisms and can be installed on braking systems already in service without modification to any part of the braking system. The present invention is a specially designed flat washer type of a measuring device intended to replace the existing spacer washer that is presently used with the installation of slack adjustable levers on the spline end of brake camshafts.

This invention is a reversible, circular flat washer type of a measuring device with calibration marks on both sides of the flat surfaces of the dial. The timing mark 3 on original equipment brake camshafts 5 and the timing mark 4 on the brake lining wear indicator gauge 1 as illustrated in figure 2 of sheet number 2 are used for timing the dial gauge to the brake camshaft on first time gauge installations. The alignment line 6 on the slack adjustable lever 7 on original equipment is used to interpret the information stored on the face of the dial gauge thereby disclosing the amount of wear that has taken place inside a brake drum compartment.

A calibration marked F on the rotating dial gauge 1 aligned to the alignment line 6 on a slack adjusting lever 7 as shown in figure 2 is used to indicate the starting point of the brake lining wear cycle and signifies that brake shoes with the full amount of brake linings were installed on the vehicle or that the slack adjusting lever has been backed off and reset to the starting position of the brake adjusting cycle. The two other calibration marks accentuated with notches on the outside circumference of the wear indicator gauge 1 signified respectively by the letter E mark the end of the brake lining wear cycle. The notches on the dial are used to accentuate the calibration marks on the face of the dial gauge and serve as delimiters to facilitate the reading of the dial gauge in visually adverse climatic conditions. The splined hole in the center of the brake lining wear indicator gauge has a series of machined grooves which are able to mate with various size shafts and grooved patterns machined on the spline end of brake camshafts.

Another novel feature incorporated in this invention is that it is a one piece gauge eliminating the need of having to manufacture a secondary co-acting part to make the invention functional. All the brake lining wear information presently available on brake shoes inside the brake drum compartment is already recorded on the flat surfaces of a single embodiment making it a single reversible brake lining wear indicator dial gauge that has eliminated all the needs of attaching tabs or protruding co-acting members exposed to road hazards in order to make the gauge functional.

Being a one piece gauge makes this invention economi¬ cally affordable to manufacture, practical in packaging and easy to install on braking systems using rotating brake camshafts equipped with slack adjusting levers.

Of the several methods of extracting the information already stored on the brake lining wear indicator dial gauge the primary method is done in the first instance by means of mating an alignment mark already existing on original equipment slack adjusting levers to the calibrations marked on the dial gauge. The secondary method αf extracting brake wear information already stored on the dial gauge when it is installed on brake camshafts that are not original equipment already installed on vehicles in the field of service is done with a straight edge ruler by forming an axial straight line to intersect the face of the dial gauge. The axial line starting from the center of the hole 11 used by the clevis pin to connect the top end of the slack adjusting lever to the lever actuator engine intersects the dial gauge on it's way to the centering hole 12 of the splined end of the brake camshaft. The calibration marks on dial gauge intersected by the axial line formed by the straight edge ruler disclose the amount of brake lining remaining on the surface of the brake shoe inside the brake drum compartment.

The calibration marks on both of the flat surfaces of the brake lining wear indicator dial gauge serve the useful purpose of being able to reverse the dial gauge on the brake camshaft for the added feature of fine tuning and alignment of the F indication mark on the face of the dial gauge to the alignment line 6 on original equipment slack adjusting lever 7.

The groves machined on the hole in the center of the brake lining wear indicator gauge are machined in such a way so that when the brake lining wear indicator gauge is turned round on the end of the brake camshaft the calibration mark F on the face of the dial gauge has changed its position, that is why the gauge is reversible. The brake lining wear indicator gauge is to replace the existing spacer washer that is presently used between the slack adjuster cover plate 2 in figure 4 and the snap ring 9 that is used as illustrated in figure 4.

The groves machined in the center hole of the dial gauge which are to match up with the splined end of brake camshafts are machined out of alignment with the F indicator mark on the face of the dial gauge so that when the gauge is reversed on the end of the brake camshaft the F indicator mark is moved off of alignment center a few degrees from the alignment line 6 on the slack adjusting lever 7. This feature is built irt to compensates for the installation of new brake linings of different thicknesses.

An other novel feature incorporated in the brake lining wear indicator gauge is the left to right and the right to left calibration marks on the face of the dial gauge. This is especially useful when installing the gauge on brake adjusting mechanisms that are left handed or right hand mounted on either side of any vehicle, the calibrations on the face of the gauge can read from left to right as well as from right to left.

When new brake linings are installed on a vehicle or partially worn out brake linings that are already in service on a vehicle, where no timing marks 3 exist on brake camshafts and where there are no alignment marks on the slack adjusting lever the method of timing and installing the brake lining wear indicator gauge is as follows: Reverse the slack adjusting cycle by means of the adjustment screw 8 on the slack adjuster 7 until the brake cam is at the beginning of the brake wear adjustment cycle. Remove the snap ring 9, and the existing spacer washer then install the brake lining wear indicator gauge 1 over the splined end of the brake camshaft making sure the calibration marked F on the face of the brake lining wear indicator gauge 1 is lined up with the center of the brake adjusting lever. The center of the brake adjusting lever is found by using a straight edge ruler to form an axial alignment line starting from the center of the clevis pin hole 11 at the top end of the slack adjusting lever to the machined centering hole 12 in the splined end of the brake camshaft that is already engaged into the slack adjuster mechanism.

The brake lining wear indicator gauge installed on the splined end of the brake camshaft was invented first of all to give the brake inspection mechanic a visual indication of the amount of brake lining wear that has taken place inside the brake drum compartment after the new brake linings were installed without having to remove the brake drum or inspection covers thereby speeding up a brake inspection safety check.

A claim ' is made for the added benefit of having a large dial gauge fastened to the end of brake camshafts, it gives the apprentice mechanic servicing the vehicle's brakes a visual warning when he is turning the brake adjustment screw the wrong way. By watching the direc¬ tion of the rotation of a large dial gauge indicating by the descending value the numerical calibrations marked on the face of the large dial gauge this would warn the apprentice mechanic he was adjusting the brakes the wrong way, he would be backing off the brakes instead of adjusting them, a mistake too often made.

The measuring cycle for the brake lining wear indicator gauge begins with the installation of new brake linings on a vehicle. When new brake linings are installed on a vehicle the adjustable lever slack adjusting mechanism is reset so the brake cam activating the brake shoes is returned to its minimal expandable position, known as the beginning of the brake adjustment cycle.

After removing the snap ring install the brake lining wear indicator gauge 1 over the splined end of the brake camshaft 5 making sure the splined groves are mated, on original equipment the timing marks 3 on the end of the brake camshaft 5 and the timing marks 4 on the brake lining wear indicator gauge 1 are in line and properly timed to each other. Then the alignment line 6 on both the slack adjuster 7 and it's cover 2 should be in alignment with the calibration mark F on the dial gauge as shown in figure 2 of the drawing.

When adjustments are made to compensate for brake lining wear that takes place inside the brake drum compartment the calibration mark F on the face of the brake lining wear indicator gauge l moves away from the alignment mark 6 on the slack adjuster 7. The numerical calibrations coming in line with the axial center of the lever reveal the amount of actual brake lining remaining on the brake shoe inside the brake drum compartment.

In the attached diagram sheet number 1 figure 1 shows a frontal view of the dial face of the unique brake lining wear indicator gauge 1.

In the attached diagram sheet number 2 figure 2 shows the brake lining wear indicator gauge 1 mounted on the spline end of the brake camshaft 5 with the timing marks 3 on the end of camshaft 5 and the timing marks 4 on the brake lining wear indicator gauge respectively timed showing the position of the marks 6 on both the slack adjuster' 7 and the cover 2 relative to the cali¬ bration mark F on the wear indicator gauge signifying the brake linings inside the brake drum compartment are new and full bodied.

In the attached diagram sheet number 1 figure 3 shows the timing mark 3 stamped on the spline end of the brake camshaft 5 and the machined centering hole 12 on the spline end of the brake camshaft.

In the attached drawings sheet number 1 figure 4 shows a side view of the brake lining wear indicator gauge 1 mounted on the splined end of the brake camshaft 5. The brake lining wear indicator gauge 1 is posi¬ tioned between the slack adjuster 7 and the snap ring 9 replacing the conventional 45 mm spacer washer. Number 10 points to a cross section of the brake camshaft support bracket.

Diagram sheet number 3 figure 5 shows an image of the brake lining wear indicator gauge installed on an S type rotating brake camshaft using a slack adjusting lever that is not original equipment. Note that the position of the F calibration mark on the face of the dial gauge is perpendicular and axially in line with the hole 11 used by the clevis pin and the centering hole in the splined end of the brake camshaft.

The inside diameter of the hole in the center of the brake lining wear indicator gauge 1 is relative to the shape and outside diameter of the brake camshaft 5. The number of groves machined in the circumference of the hole in the center of the brake lining wear indicator gauge 1 is relative to the number of grooves machined on the splined end of the brake camshaft 5. Example: A brake camshaft with a fine spline requires a brake lining wear indicator gauge with a fine splined center hole, while a brake camshaft with a coarse spline requires a brake lining wear indicator gauge with a coarse splined center hole. The brake lining wear indicator gauge is calibrated on both sides for the purpose of installing the gauge on the left or the right side of the vehicle's braking system.




 
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