The Allen-Liversidge Front-Wheel Brake.
Page 17
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On the afternoon of Thursday, the 23rd instant, by the courtesy of the Vanguard Motorbus Conipany, Limited, an interesting demonstration took place, at the Albany Street Garage, of the capabilities of the AlienLiversidg-e front-wheel brake. There is nothing of great novelty in the construction of the brake itself, but the feature which the proprietors have fully protected, and in the ownership of which they look for an adequate return for their enterprise, is the arrangement which they have adopted to ensure a differential action between the two brakes ; this, however, is independent of, and in no way interferes with, the capacity of the steering gear, a result that is ensured by the employment of a flexible-wire actuating gear, which is located at various points by suitably arranged pulleys.
The disposition of the various parts is shown in the sketch which we re
produce. it will be seen that the necessary differential action is ensured by the provision of guide pulleys, which are carried on extensions of the vertical stub-axle pins, and by the fitting of a pulley on the main actuating lever. At the request of the representative of -`THE COMMERCIAL MOTOR" an interesting series of tests was carried out to His requirements. Two cars_ were employed : one was of the usual foureylinder type, and weighed about 15 cwt., the other was a horizontall!ylindered American runabout. Both 3f these machines were. fitted with front-wheel and back-wheel brakes.
A. properly-greased -surfacehad been prepared, on a -sloped portion of the garag-e floor. Each. car was, in turn, driven at full speed through the shed, mtil it arrived at the greased surface, Alen the driver was instructed to kick
the wheels completely over, and, at the same time, to apply either one of the sets of brakes. During the application of the hind brakes, a conventional 18odegree side-slip developed ; but, when a test was made, under precisely similar conditions, with the exception that the front brakes only were applied, the car tended to answer the helm, even when the front wheels were locked, and the slip which took place was of no importance. The genuineness of this demonstration was strikingly verified when one of the vehicles was driven backwards over the same treacherous
stretch ; the real front brake now became a hack brake, and, when applied, it succeeded in producing the usual wild career across the greased surface ; the real hind brakes, which were thus temporarily acting as front brakes, retarded the machine without producing any .deviation from the straight-forward path. The application of .both pairs of brakes simultaneously. resulted . in a very steady and sudden stop, with but little tendency to side-slip.
The conclusions arrived at by our representative were that : (1) the appli
cation of this front-wheel brake can be effected with very little resultant tendency to side-slip ; (2) the locking of road wheels temporarily converts them into skates, and, when this happens on the hind wheels, the conditions are often favourable for them to " climb round," but, when it happens to the front wheels, there is no reason why they should alter their direction to any extent ; (3) although the front brake reduces the risk of side-slip due to braking, the driver no longer has control over the direction of the machine while they are applied ; (4) under certain con ditions, the -front-wheel. brake-apparently has very material advantages, but it is probable that it should be used as an additional brake,. and should not supersede the.conventiOnal back brake. Although a large percentage of Sideslips is caused by injudicious braking, it must be remembered that, frequently, slipping takes place which. has no reference to the braking system 'which is employed ; but, as.an insurance against dangerous side-slip on many occasions, the front-wheel brake has, 'very clearly, much to warrant consideration.