AU778704B2

AU778704B2 - Brake testing

Info

Publication number: AU778704B2
Application number: AU35034/01A
Authority: AU
Inventors: Richard Gartner
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-04-06
Filing date: 2001-04-06
Publication date: 2004-12-16
Anticipated expiration: 2021-04-06
Also published as: AU3503401A

Description

AUSTALIARegulation 3.2 Parents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invenion Ttle:BRAKE TESTING *The following statement is a full description of this invention, including the best method of performing it known to me:- (See Within) FIELD OF THE INVENTION THIS INVENTION relates to the testing of vehicles and is-more specifically concerned with apparatus for determining the braking performance of individual wheels of a vehicle.

STATE OF THE ART Testing of a vehicle's brakes first takes place when the vehicle is manufactured prior to it being distributed to sales outlets. Further testing of the brakes on an annual basis may then be called for by legislation when the vehicle is more than a certain age. Such 0.:i'o legislation usually sets performance criteria which must be complied with as a condition of 0 the annual re-registration of the vehicle.

Many garages in Australia are equipped with bays containing apparatus for testing the brakes and providing a test bed. The vehicle is driven at a slow speed to a position at which each of its wheels is resting on a separate test plate and it is then sharply braked.

The momentum of the vehicle during braking is transmitted as horizontal thrusts applied by the vehicle's wheels to the individual plates. Thrust sensing and recording cells 15 associated with each of the plates enable the braking efficiency of the vehicle's wheels to be measured and checked to establish their compliance with the required parameters set by the legislation.

The apparatus used to test the brakes of a vehicle in a garage is relatively expensive to install and to maintain. It often takes the form of a concrete foundation having four shallow rectangular wells to receive the individual plates. The floor of each well is formed with a pair of smooth horizontal tracks extending in the direction of movement of the vehicle during braking, and on which run rollers which support the weight of the vehicle when resting on the plates. The cell is also firmly mounted in the well and is rigidly connected to the associated plate so that its electrical output provides a measure of the braking load applied by one of the vehicle's wheels. Electronic recording equipment connected to the cells computes whether the braking ability of the vehicle's wheels falls within the required tolerances.

The above apparatus requires the construction of smooth parallel tracks to be formed in the rough concrete floors of the wells. The plates also have to be fabricated so that they are sufficiently rigid to absorb the braking thrusts without flexing. In practice such plates are commonly fabricated from a welded ladder-like frame of steel bars welded to the underside of a steel strip formed with a knurled upper surface to provide a firm grip for the vehicle's tyres. The rollers are carried on shafts set in the sides of the frame and the structure has to be carefully assembled to ensure that the weight of the vehicle on the plate is shared equally between the supporting rollers. A rigid connection secures each plate to the associated cell which is anchored rigidly to the concrete wall of the well.

It will be appreciated that garages accumulate grit and dirt and this inevitably finds its 6:*6 way into the wells over a period of time and can lodge between the rollers and their tracks ii. 10 or between the plates and the sides of the wells. It is therefore necessary for the test bed to be stripped down and cleaned at regular intervals. Recalibration is also necessary to ensure that aging of the components of the test bed does not impair their performance. Such maintenance is normally undertaken under a maintenance contract and this involves a further financial burden on the garage.

An object of this invention is to provide a less costly apparatus for testing the braking performance of a vehicle.

STATEMENT OF INVENTION In accordance with the present invention, apparatus for testing a vehicle's brakes is provided with plates for supporting the respective wheels of a vehicle being tested and which each has an associated load-sensitive measuring cell connected to compute the braking performance of the associated vehicle wheel; each plate being formed by a channel-shaped strip having its intermediate portion providing a wheel-engaging surface of the plate, and its parallel side portions each being provided with means for supporting a set of spaced roll surfaces which carry part of the weight of the vehicle when one of its wheels is resting on the intermediate portion of the strip.

PREFERRED FEATURES OF THE INVENTION Suitably each roll surface is provided by part of the circumference of a roller.

Preferably there are two sets of rollers provided on each plate, each set being mounted on a respective one of the two side-portions of the plate.

Each set of rollers runs on a respective one of two parallel tracks each formed by a horizontal steel strip resting on a layer of material which is soft when laid on the concrete foundation of the apparatus and which subsequently hardens to transmit the weight applied to the plate to the foundation. It is much easier and cheaper to provide a smooth horizontal track for each set of rollers this way, than by specially treating the concrete of the foundation to smooth out the inherent roughness of its surface.

o *o Tracks made as described above have the advantage that they lie above the floor of the 10 foundation and are less likely to be contaminated by grit entering the well. They may also be mounted directly on the upper horizontal surface of a foundation plinth which is not formed with wells. In such an arrangement the vehicle is driven onto the plates which are arranged at a level above the upper surface of the foundation plinth. A flexible web or block of a rubbery or foamed flexible material may be secured between the 15 sides of the plates and the upper surface of the foundation to provide a dirt and grit seal around each plate. Preferably the upper surface of the web or block slopes downwardly towards the upper surface of the foundation. The tracks are then better protected against the risk of debris or dirt impairing the movement of the rollers along them. The use of a channel strip as the plate enables the sets of rollers to be located in the channel formed between the side portions of the strip. Each side portion may be provided with its own set of rollers mounted on their own track. Alternatively a single set of axiallyparallel rollers may be arranged to span between the strip side-portions and the concrete foundation and may be supported by respective shafts mounted at each end in the strip side-portions. Each set of rollers may then be supported on two parallel tracks close to their opposite ends, respectively.

The invention will now be described in more detail, by way of example, with reference to the accompanying largely diagrammatic drawings, in which:- FIGURE 1 is a side view of apparatus for testing the braking performance of a vehicle's wheels and shows the positions of rollers in phantom outline; FIGURE 2 is a plan view of the apparatus of figure 1; FIGURE 3 is a cross-section through an enlarged part of the apparatus and is taken on the line and in the direction of the arrows m-9 of figure 2; FIGURE 4 is an inverted plan view of a plate formed by a channel strip equipped with rollers beneath and forming part of the apparatus, the connection of a load- ***measuring cell being illustrated in phantom outline; FIGURE 5 is a vertical cross-section of a strip and a layer of putty sandwiched between the strip and a concrete foundation, to provide a track on which a set of S°rollers is mounted; and, FIGURE 6 is a scrap detail showing how a thrust-measuring cell is connected to one end of a side-portion of a channel plate.

Figures 1 and 2 shows apparatus for testing the brakes of a vehicle and which comprises a concrete slab 1 providing a foundation and have a level, if not smooth upper surface 2.

Two pairs of ramp surfaces 3 and 4 allow a vehicle to be driven onto and off two, spaced, parallel wheel-supporting zones 9 of a generally flat horizontal test bed 5 located between the ramp surfaces 3 and 4. Two pairs of inverted channel plates 7 and 6 are spaced from one another in the direction of travel of the vehicle when driven onto the test bed, by a distance which enables the front wheels of the vehicle to be supported by the plate 6 simultaneously with the rear wheels of the vehicle being supported by the plate 7. Fixed spacer plates 8 are located between the plates 6 and 7 on each side of the test bed and are approximately level therewith.

Referring next to figures 3 and 4, each of the plates 6 and 7 rests on two sets of four rollers 1 which re located within the channel of the plate and extend slightly beneath its lower edge. The undersides of the rollers 10 extend slightly beneath the under edges of 4 6 the plate and the two sets of rollers rest respectively on a pair of parallel, spaced, level tracks 11. Each roller has a shaft 13 journalled at one end in a bearing (not shown) mounted in one of the two parallel side-portions 14 of the plate. The upper surface of the plate is roughened to enable it to be gripped by a wheel tyre during braking of the vehicle, and is provided by the intermediate portion of the plate 6. Plate 7 is of similar construction to plate 6.

As shown in figure 6, each plate is associated with a thrust-measuring cell 20 for sensing and measuring the thrust exerted on the plate during braking. The inside surface of one side-portion 14 of the plate is formed with a pair of spaced, inwardly-directed lugs 21. A 10 rigid angle arm 22 connected to the cell 20, has a threaded aperture 23 at one endportion 24 which is located between the lugs 21. A threaded shank 25 is screwed through the aperture 23 and is rotated sufficiently to bring one of its ends into engagement with one of the lugs 21 so that, during braking of the vehicle, the horizontal thrust exerted on the plate 6 is transmitted by way of the lug 21 and the shank 25 to the arm 24 and thus to the cell 20. The shank 25 has a lock nut (not shown) to enable its position to be fixed during setting-up and calibration of the apparatus.

The sets of rollers 10 are respectively supported by a pair of smooth horizontal tracks 1 1 constructed as shown in figure 5. Each track comprises a flat horizontal steel strip 26 resting on a layer 27 of hardened putty or equivalent material, which anchors the strip 26 to the foundation 1. It is important that all of the rollers 10 bear equally on the supporting track 11, as shown in figure 3. This is achieved during assembly of the apparatus, by having the putty or equivalent medium sandwiched, while soft and pliant, between the strips 26 and the foundation 1. The plates 6 are then placed in their working positions and a flat horizontal load surface is supported on them. This causes the layer to yield while still soft, until all of the rollers have found a common horizontal level on their tracks 11. The layer 26 is then allowed to harden.

Referring back to figure 2, a soft rubber web 30 is attached between the sides of the plates 6, 7 and 10 and the foundation 1 to prevent dirt and grit finding its way beneath the Plates and i.y ,,trfi9 with the correct movement of the rollers 10 on the tracks 11. The location of the strips 26 of the tracks above the upper surface of the foundation 1, also helps to prevent any loose material which may accumulate beneath the plates, from finding its way onto the upper surfaces of the tracks 11. The web 30 slopes downwardly from the plate towards the upper surface of the foundation. This helps in assisting easy cleaning of the test bed after it has been used. The resilience of the rubber is such that it does not interfere with the operation of the plates 6 and 7 and it serves to reduce the times when periodic maintenance and calibration of the apparatus is necessary.

Although the above-described test bed is located above the surface of the slab foundation 1 the operating parts of it may instead be located in rectangular shallow wells 10 formed in the upper surface of the foundation 1 in much the same way as has already been described with reference to the prior art. The upper surface of the test bed is then o *almost flush with the surface of the foundation rather than being raised with respect to it.

The apparatus is used as follows.

A vehicle to be tested is driven at a predetermined speed of about walking pace onto the test bed and is suddenly braked when its wheels are resting on the respective plates 6 and 7. The braking causes the sharp drop in momentum of the vehicle to be converted into horizontal thrusts which act on the plates so that they are urged against the respective sensing and measuring cells 20. The cells are connected to a computer and recorder (not shown),which compares the braking thrusts on each pair of coaxial wheels, the ratio of the braking of the front and back wheels, and the individual braking power of each of the wheels with those required. A recorder (not shown) indicates with its output whether the vehicle complies with the braking test requirements or whether adjustment of individual brakes is necessary.

Claims

1. Apparatus for testing a vehicle's brakes, provided with plates for supporting the respective wheels of a vehicle being tested and which each has an associated load- sensitive measuring cell connected to compute the braking performance of the associated vehicle wheel; each plate being formed by a channel-shaped strip having its intermediate portion providing a wheel-engaging surface of the plate, and its parallel side portions each being provided with means for supporting a set of spaced roll surfaces which carry part of the weight of the vehicle when one of its wheels is resting on the intermediate portion of the strip.

2. Apparatus as set forward in claim 1, in which the or each roll surface is provided by a roller.

3. Apparatus as set forth in either of claims 1 or 2, in which each set of rollers runs on a track formed by horizontal steel ribbon resting on a layer of material which is soft when laid on a concrete foundation of the apparatus and which subsequently hardens to transmit to the foundation the weight applied to the rollers.

4. Apparatus as set forth in any one of claims 1, 2 or 3, in which a set of rollers is supported by being journalled into bearings provided in one of the two plate side-portions.

Apparatus as set forth in any one of the preceding claims, in which the plates are positioned to support the tyres of a vehicle being tested above the level of the upper surface of a foundation for the apparatus.

6. Apparatus as set forth in any one of claims 1 to 4, in which the plates are arranged approximately coplanar with the upper surface of the foundation and the rollers supporting the plates are accommodated in shallow wells provided in the upper surface portion of the foundation. 9

7. Apparatus set forth in any one of the preceding claims, in which a resilient sealing web spans between the upper edges of the plates and the foundation to reduce the entry of grit and dirt into the spaces beneath the plates.

8. Apparatus as claimed in claim 1, arranged and adapted to operate substantially as described with reference to the accompanying drawings or the above-described modifications thereof. Dated this A(day of April 2001. RICHARD GARTNER (Applicant's Patent Attorney)