GB2087491A

GB2087491A - Handbrake Mechanism of a Motor Vehicle

Info

Publication number: GB2087491A
Application number: GB8036749A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-11-15
Filing date: 1980-11-15
Publication date: 1982-05-26

Abstract

An elastic member or members (a) is inserted in the handbrake mechanism of a motor vehicle which elastic member has a force and extension relationship to suit the vehicle, and the tensile and compressive distance is related to the travel of the hand brake ratchet so as to allow a safe margin. The assembly as in Fig. 1, incorporated into the brake line at some point between the hand lever and the brake shoes. The tension spring (a) is designed to give the required amount of extension in the slot (g) in the fail safe side plates so that a suitable notch can be easily selected on the hand brake ratchet in relation to the application of human strength. The elastic member may be metal, rubber, synthetic polymer and may act in tension, compression, bending or torsion. <IMAGE>

Description

SPECIFICATION Modulator and Energiser for Vehicle Handbrake.

Description of the Invention General Statement In general the hand brake of the modern generation of motor vehicle, particularly the private car, suffers from the following operational defects: 1. There is very little scope for applying the brake progressively or varying the braking power at the hand lever-in other words the brake is either "on" or "off". It is difficult to apply a precise degree of braking to suit differing road conditions.

This renders the brake almost useless when it is required to perform its legal function as an emergency brake.

2. The above effect may be so pronounced as to be unable to select a suitable notch on the brake ratchet, and the brake is either not hard enough on or is overstrained. The factor also makes the performance of a hill start more difficult.

3. When "2" applies there are occassions when the hand lever has to be applied with such power as to make its release almost impossible (particularly for women). In many cases the driver adopts a method of impact application to attain an effective notch on the ratchet, and then finds the brake difficult to release.

4. Because of "1" there is a possibility that the hand brake may re-adjust itself while the vehicle is standing due to a temperature change in the length of the brake lines or to loading or unloading affecting the geometry of the system.

There is no available energy designed into the system to compensate for these effects. This may result in a releasing or an excessive tightening of the brake mechanism with attendant danger, the releasing allowing the vehicle to run away, the exessive forces causing maladjustment or actual failure of the brake parts.

5. All the above defects are rapidly worsened by the use and age of the vehicle and unsatisfactory hand brakes are a major source of failure in M.O.T. tests.

The above defects are all due to the extreme rigidity, or lack of elasticity, of the lines and linkages between the hand lever and the brake shoes.

This invention takes the form of an elastic member or members which is/are inserted in the brake mechanism to introduce a precise degree of elasticity in the line between the hand-lever and the brake shoes, in such a way that a degree of application force, varying from gentle to severe, can be applied to the brake shoes.

This elastic member would be constructed in such a way as to have a force and extension relationship to suit the vehicle to which it is fitted.

The maximum tensile or compressive forces in the elastic member would be related to a reasonable application force which could be applied by human strength, male or female, and may be adjustable, to suit individual requirements.

The tensile or compressive distance would be related to the travel of the hand brake ratchet so to allow a safe margin of travel for periodic adjustment.

The tension or compression member would incorporate a fail-safe rigid stop which would come into operation in case of failure of the elastic members. This stop would come into operation before the brake lever had reached the maximum extent of its travel to ensure an effective application of the brake. The elastic member may be a single or multiple arrangement, for example there may be one member in the line between the lever and the compensator, or there may be three members, one as above and one in each of the lines from the compensator to the brake shoes.

The elastic members may form sub-assemblies built into the hand lever assembly, to the compensator assembly, or to the brake backplate.

The elastic member could be made of any elastic or spring-like material such as metal, rubber, or synthetic polymer. The elastic member could act in any manner such as tension, compression, bending or tortion.

The elastic member could be situated at any point in the brake line between the application handle and the brake shoes. The elastic member may be of the type with an additional tension built in.

Operation of the Invention The application force from the brake lever would be transmitted to the elastic member and then from the elastic member to the brake-shoes.

Upon resistance being felt at the brake lever the lever would be notched back progressively until the required amount of braking force is applied, the elastic member supplying a calculated degree of flexibility in the brake line to enable a suitable notch to be selected on the hand-brake ratchet, with a small degree of elasticity remaining to enable the elver to be released.

This application of the brake would energise the elastic member, which would then remain energised as long as the brake was applied, thus introducing an almost constant dynamic braking force into the system. Should any change in the brake linkages or in the geometry of the brake system take place while the vehicle is being held by the brake, this energy would be available to maintain a braking force.

It can now be seen that the introduction of this modulator and energiser into the brake mechanism eliminates all the disadvantages of conventional systems listed above.

This invention has been devised particularly for the benefit of women drivers to assist them in the application and release of the hand brake and in performing the difficult manoevre of a hill start.

It may be that this invention has been accidently introduced into certain vehicles, in the past, by tension in rods or wires, or by torsion of bars or tubes but this was not a precise or calculated force or extension with a fail-safe device which is the substance of this invention.

Example One embodiment of this invention would consist of a heavyduty tension spring (a) one end of which is shackled to the cable (b) from the hand lever and the other end to the cable (c) to the brake shoes. The rate of this spring would be precisely calculated so that the maximum application of human strength on the brake lever would only extend the spring a predetermined distance, decided by the desired number of notches on the brake ratchet, say 3 or 4 notches.

To give a progressive and effective application of the brake. In this final position there would still be a degree of extension remaining in the spring to enable the lever to be released without over straining the strength of the driver or of the mechanism.

The fail-safe device consists of two steel sideplates (e) secured to the brake cables by the bolts (f). One of these bolts runs in a slot (g) to enable the spring to extend but should the spring fail, the bolt would come up against the end of the slot and the braking pull would then be transmitted evenly through the side-plates.

The length of the slot would be long enough to enable the spring to perform its modulating and energising function but would not be so long as to prevent an application of the brake in case of failure of the spring.

The above module would be inserted in the brake cable between the hand-lever and the compensator, or three could be used, one as above and one each in the two cables between the compensator and the brake shoes.

Claims

Claims

What I claim is a flexible element or elements for inserting at any point in the conventional handbrake system of a motor vehicle, between and including the handbrake lever and the brake mechanism acting on the vehicle wheels comprising:

1. A flexible element in which the design of the flexible medium in the element is calculated and contrived to give a precise and required amount of flexibility in direct relationship to the amount of force from zero to maximum applied to the brake system by the arm of the driver of the motor vehicle to which the element is fitted.

2. A flexible element, as in Claim 1, incorporating a fail-safe device in event of the failure of the flexible medium.

3. A flexible element, as in Claim 1, using any known elastic material for the precisely designed flexible medium.

4. A flexible element as in Claim 1 in which the flexible medium is stressed in any manner e.g.

extension, compression, torsion or bending.

5. A flexible element as in Claim 1 as an individual component or included in the assembly of any other components of the brake system either in series or in parallel.

7. A flexible element as in Claim 1, in which the flexible medium is in a state of initial tension.

8. A range of flexible elements, as in Claim 1, to suit the individual requirements of different drivers.

9. A flexible component designed into the brake system so as to perform the function of a flexible element, as in Claim 1 with or without a fail-safe device.

New Claims or Amendments to Claims filed on 1 9 Jan. 1982.

New or Amended Claims:

10. Any motor vehicle including a device in the hand brake mechanism as claimed in any of the preceding claims no's 1-9.