GB1558917A - Test bench for checking the brakes of a vehicles - Google Patents

Description

(54) TEST BENCH FOR CHECKING THE BRAKES OF A VEHICLE (71) We, ETABLISSEMENTS M.

MULLER & CIE., a Body Corporate organised under the Laws of France, of 50-56 rue des Tournelles, Paris 3seme, France, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be described in and by the following statement: The present invention concerns the benches used to test the brakes on a car.

There are already many types of test benches designed for this purpose. However, these are benches designed to be set up in a fixed position, e.g. inside a garage or service station.

On the other hand, the present invention proposes to make a test bench which is very simple in design and needs practically no source of energy, so that it can form an easily-transported unit capable of being used anywhere. This bench can also be used to set up spot testing stations along a road.

However, it can also be used in a garage or service station.

Moreover, this bench is designed to test, not the value of the static braking torque, measurement of which is of no interest, but the extent of the frictional resistance imposed by the brakes when the wheels are rotated. In fact, it is the dynamic frictional resistance which determines the true efficiency of the brakes of a vehicle.

According to the invention there is provided a test bench for checking the brakes of a vehicle, comprising two sets of rotary rollers capable of taking the two front or rear wheels of a vehicle, and a measuring device which includes a lever for rotating one of the rollers in either set, the lever being made up at its base by a bendable test bar in spring loaded contact with which there is a feeler mounted pivotally on a rigid bracket fixed to the base of this lever, the movement of said feeler controlling a potentiometer connected to an electric circuit comprising an indicating instrument, so that in use when the front or rear wheels of the vehicle are supported on said rollers, with the brakes of said wheels applied and the lever is moved to rotate one of the rollers of one set, the frictional resistance to this rotation imposed by the vehicle's brakes causes the lever to bend to an extent indicated on said indicating instrument.

Thus, after having clamped the brake pedal of a car by means of a suitable implement, the brakes of one of the wheels placed on this bench can be tested by coupling the control lever of the measuring device to one of the rollers supporting this wheel. It is sufficient to rotate the wheel in question by means of this lever, preferably in the opposite direction to the feeler. The indicating instrument, e.g. a galvanometer associated with the measuring device then makes it possible to record the value of the frictional resistance opposed to the wheel's rotation.

Moreover, according to a preferred characteristic of this bench, the control lever carries an electric contact which can be operated by a fixed component on the bench before the lever reaches the end of its travel, this contact being inserted into the circuit of the measuring instrument in such a way was to cut off the supply to the latter when it is operated.

However, other peculiarities and advantages of this test bench will emerge from the following description. This is given with reference to the drawing appended merely as an indication, whereon: Figure 1 is a part perspective view of this test bench; Figure 2 is a perspective view illustrating the use of this bench; Figure 3 is a diagrammatic elevation view of the measuring device provided in this bench; Figure 4 is a similar view illustrating the practical use of this device.

This test bench includes two sets of rotary rollers designated by the general reference 1. The two rollers 2a and 2b in each set are mounted rotatingly in a frame 3 and the two corresponding frames are themselves mounted so as to slide in a transversal direction on the bed 4 of this bench. This makes it possible to adjust the spacing of the two sets of rollers in terms of the track of the vehicle whose brakes are to be tested.

On one of the sides of the bed 4, there are two slanting ramps 5 designed to enable the front or rear wheels R of a vehicle V to be positioned on the two sets of rollers. In the case of a mobile unit, these two ramps can consist of two sheet-metal components, articulated around horizontal axles 6 and capable of being folded back for transport.

On the opposite site, this bench comprises two tracks 7 designed to take the front wheels of a vehicle when the brakes on its back wheels are being tested. As already indicated, this bench can be made in such a way as to be easily transported.

The two rollers in each set are coupled to each other in rotation, e.g. by means of a chain 2. Moreover, a clamping component la is provided, making it possible to immobilise these rollers when the vehicle is being removed. In fact, it is necessary at that time for its wheels to be able to grip on the rollers.

In accordance with an essential characteristic of the invention, a driving and measuring device is provided, making it possible to rotate one or other set of rollers and at the same time to record the value of the frictional resistance opposed to this movement by the fact that the vehicle's brakes are on.

This device consists of a control lever 8 made up of a bending test bar 9 and a rigid operating handle 10 (see Figure 3). The bending test bar 9 is integral with a base 11 carrying a coupling finger 12. This is designed to engage in one or other of the holes provided for the purpose in a square 13 carried by the projecting end of the shaft of roller 2a on each of the two sets. This square advantageously comprises four holes positioned at right-angles, which makes it possible, at the start of the operation. to put the control lever 8 in the required angular position which is shown in Figure 2, irrespective of the angular position of rollers 2a and 2b.

The base 11 of the control lever carries a rigid bracket 14 which extends opposite one of the sides of the bending test bar 9. This bracket carries a feeler 15 the free end of which is placed in contact with the corresponding side of the bending test bar 9, a spring (not shown) tending to apply the end of this feeler constantly against this bar.

This feeler is pivotally mounted on the bracket 14.

However, the hinge pin 16 of this feeler is integral with the latter and controls a potentiometer connected to an electric circuit 17 which also comprises an indicating instrument 18, e.g. a galvanometer. This circuit can be supplied by an easily transported accumulator or even possibly by the battery on the vehicle being tested.

The gauging of the measuring galvanometer is such that the needle on its dial is opposite the zero mark when the bending test bar 9 is in the "at rest" position shown in Figure 3. Thus, this needle is able to indicate the extent of bending of bar 9 in the direction of arrow F, i.e. in the direction away from the feeler. In fact, in such a case, the latter has to pivot in the same direction to maintain contact with the bending test bar (see Figure 4). This, therefore, operates the potentiometer and thus causes a change in the position of the galvanometer 18 needle.

In order to test the brakes on wheel R placed on one of the sets of rollers, the brakes on that wheel obviously have to be put on beforehand. This can be done by means of a pressure apparatus placed in contact with the brake pedal and which is preferably fitted with a gauge to check that the pressure is the same in each case, i.e. on each of the wheels tested one after the other.

Lever 8 is then coupled to the driving square 13 by placing this lever in a position slanting in the opposite direction to the direction of movement intended for this lever (to the left in the case of the drawing in Figure 2). Then, the operator pulls on the lever to make it pivot in the direction of arrow F. At the beginning, the wheel stays perfectly still because it is held by the brakes.

In these conditions, bending test bar 9 bends away from the bracket 14 of the feeler. As already indicated, this causes the latter to pivot and, consequently. the needle of the measuring galvanometer 18 to move.

At the beginning this movement indicates the value of the static braking torque, since the wheel is locked.

However, this value increased until the time when the wheel is rotated, despite being held by the car's brakes. From that time on, the value of the braking torque indicated by the galvanometer is made to come down until it reaches a value indicating. to some extent, the "dynamic braking" torque, i.e. the value of the frictional stress exerted by the corresponding brake drum or disc when the wheel rotates. Now, this bench is precisely designed to allow this value to be tested.

An electrical contact 19 is inserted in the galvanometer circuit and operates in such a manner that when it comes against a fixed component of the bench, before it reaches its end of travel position, it causes the galvanometer circuit to be opened and the galvanometer needle to be locked in position, enabling one to read the value indicated thereby.

The same operation is then carried out on the other wheel in the same set of the vehicle's wheels. This therefore makes it possible to check whether the brakes on both wheels in the same set exert the same frictional stress when they are in service. In order to test the brakes on the other wheel in the same set, it is sufficient to remove lever 8 and fit it on the driving square 13 of roller 2a on the other set of rollers.

Because of the way it is arranged, this bench can be used anywhere without having recourse to a source of energy. This enables mobile units to be made, which can be used for spot tests at the roadside. However, this bench can also be used in a fixed position in a garage or service station. In this case, this bench has the advantage of being much more simple and less expensive than the usual brake testing benches.

Nevertheless, in either case, the bench according to the invention makes it possible to test, not the static braking couple the measurement of which is of no real interest, but the extent of the frictional stress exerted by the brakes during rotation of the wheels.

Now, it is precisely the value of this frictional stress which it is important to know in order to obtain information on the efficiency of a vehicle's brakes.

Moreover, this bench makes it possible to detect any ovalisation of the brake drums or buckling of the brake discs. For this purpose, it is sufficient to carry out several test operations with the wheel in different angular positions. Moreover, this bench also makes it possible to test the efficiency of a vehicle's hand brake.

WHAT WE CLAIM IS; 1. Test bench for checking the brakes of a vehicle, comprising two sets of rotary rollers of taking the two front or rear wheels of a vehicle. and a measuring device which includes a lever for rotating one of the rollers in either set, the lever being made up at its base by a bendable test bar in spring loaded contact with which there is a feeler mounted pivotally on a rigid bracket fixed to the base of this lever, the movement of said feeler controlling a potentiometer connected to an electric circuit comprising an indicating instrument, so that in use when the front or rear wheels of the vehicle are supported on said rollers, with the brakes of said wheels applied and the lever is moved to rotate one of the rollers of one set, the frictional resistance to this rotation imposed by the vehicle's brakes causes the lever to bend to an extent indicated on said indicating instrument.

2. Test bench as claimed in Claim 1, wherein the indicating instrument is a galvanometer.

3. Test bench according to Claim 1 or 2, characterised in that the lever is a removable unit which can be coupled in the required angular position, to the shaft of one of the rollers in each set.

4. Test bench according to Claim 3, characterised in that the shaft of one of the rollers in each set comprises an extension which has several holes in different angular positions, each of which can take a driving finger carried by the base of the lever.

5. Test bench according to any one of the foregoing Claims, characterised in that the control lever carries an electric contact which can be operated by a fixed component on the bench before the lever reaches the end of its travel, this contact being inserted into the circuit of the measuring instrument in such a way as to cut off the supply to the latter when it is operated.

6. Test bench according to any one of the foregoing Claims, characterised in that the two rollers in each set are coupled in rotation, and a clamping component is provided making it possible to immobilise them at the end of the operation in order to remove the vehicle which has been tested.

7. A test bench as claimed in Claim 1, substantially as hereinbefore described.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. An electrical contact 19 is inserted in the galvanometer circuit and operates in such a manner that when it comes against a fixed component of the bench, before it reaches its end of travel position, it causes the galvanometer circuit to be opened and the galvanometer needle to be locked in position, enabling one to read the value indicated thereby. The same operation is then carried out on the other wheel in the same set of the vehicle's wheels. This therefore makes it possible to check whether the brakes on both wheels in the same set exert the same frictional stress when they are in service. In order to test the brakes on the other wheel in the same set, it is sufficient to remove lever 8 and fit it on the driving square 13 of roller 2a on the other set of rollers. Because of the way it is arranged, this bench can be used anywhere without having recourse to a source of energy. This enables mobile units to be made, which can be used for spot tests at the roadside. However, this bench can also be used in a fixed position in a garage or service station. In this case, this bench has the advantage of being much more simple and less expensive than the usual brake testing benches. Nevertheless, in either case, the bench according to the invention makes it possible to test, not the static braking couple the measurement of which is of no real interest, but the extent of the frictional stress exerted by the brakes during rotation of the wheels. Now, it is precisely the value of this frictional stress which it is important to know in order to obtain information on the efficiency of a vehicle's brakes. Moreover, this bench makes it possible to detect any ovalisation of the brake drums or buckling of the brake discs. For this purpose, it is sufficient to carry out several test operations with the wheel in different angular positions. Moreover, this bench also makes it possible to test the efficiency of a vehicle's hand brake. WHAT WE CLAIM IS;

1. Test bench for checking the brakes of a vehicle, comprising two sets of rotary rollers of taking the two front or rear wheels of a vehicle. and a measuring device which includes a lever for rotating one of the rollers in either set, the lever being made up at its base by a bendable test bar in spring loaded contact with which there is a feeler mounted pivotally on a rigid bracket fixed to the base of this lever, the movement of said feeler controlling a potentiometer connected to an electric circuit comprising an indicating instrument, so that in use when the front or rear wheels of the vehicle are supported on said rollers, with the brakes of said wheels applied and the lever is moved to rotate one of the rollers of one set, the frictional resistance to this rotation imposed by the vehicle's brakes causes the lever to bend to an extent indicated on said indicating instrument.

2. Test bench as claimed in Claim 1, wherein the indicating instrument is a galvanometer.

3. Test bench according to Claim 1 or 2, characterised in that the lever is a removable unit which can be coupled in the required angular position, to the shaft of one of the rollers in each set.

4. Test bench according to Claim 3, characterised in that the shaft of one of the rollers in each set comprises an extension which has several holes in different angular positions, each of which can take a driving finger carried by the base of the lever.

5. Test bench according to any one of the foregoing Claims, characterised in that the control lever carries an electric contact which can be operated by a fixed component on the bench before the lever reaches the end of its travel, this contact being inserted into the circuit of the measuring instrument in such a way as to cut off the supply to the latter when it is operated.

6. Test bench according to any one of the foregoing Claims, characterised in that the two rollers in each set are coupled in rotation, and a clamping component is provided making it possible to immobilise them at the end of the operation in order to remove the vehicle which has been tested.

7. A test bench as claimed in Claim 1, substantially as hereinbefore described.