BRAKES AND BRAKE GEARS.
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A Résumé of Recently Published Patents.
THE BRAKE gear which is described, in specifination
No. 189,845, by T. H. Cole, is of interest, amongst other things, because of its rather ambitious schedule of objectives. it is designed for use in connection with the brakes on trailers, and the principal aim is to pmovide a brake which will be more or less automatic in its operation, which will be rendered inoperative when tractive force is applied to the drawbar of the trailer, but will be brought into operation when the tractive force ceases to be excited, or as and when required.
What might be termed the secondary advantages and objects of this invention are nuffierous. Means are provided, for example, to prevent the brakes coming into action unless, and until, the drawbar recedes to its inner limit (or nearly so), thus preventing unnecessary braking when the drawbar is only retarded owing to the vibration which is set up when the vehicle is passing over ball roads. The mechanism is a simple series of trip gears, of the type which it is impossible to describe without entering into the fullest detail, for which purpose the reader will naturally prefer to consult the specification itself. The gear is arranged so that it locks the brakes out of action after the first forward movement of the drawbar and also disconnects them from the draWbar previous to further forward motion thereof. The brakes are thus held entirely out of action, notwithstanding the effect of bad going; they are not brought into use again until the rearward motion of the drawbar is sufficiently emphatic and extensive to release a secondary trip gear which sets free the holding-off gear and permits the brakes, to be applied. Use of the shock-absorbing spring which is usually fitted to a trailer drawbar is made to facilitate the operation of this device, and the inovement,of the spring to and fru along the. bar provides the operative mechanism for the trip gear. Either brakes or springs may be used to provide the braking force, but in either case means are provided for adjustment of the brakes in accordance with the load or other controlling circumstances.
A Useful Emergency Brake.
An emergency brake, which is additional to those ordinarily and legally fitted to a motor vehicle, is described in specification No. 189,849, by A. Wondhead and another. A pair of telescopic levers are piVoted to the chassis frame, one at each side, and either ifi front of or behind the rear wheels. In front if required in the. ordinary way as brakes; behind if to serve as slica•gs. A foot is pivoted to the lower end of each lever, the arrangement being such that, as the lever is released from its normal position, in which it lies snugly under the body of the vehicle, it falls into a vertical, or nearly yea. Heal, position, with the foot in close contact with the ground. Attached to the lever at a point immediately above the font is a roller which, when the lever is in its operative position, with the foot on the ground, makes contact with the tyre of the road wheel at a point about half-way between the ground and the axle.
B46 This ensures that the road wheels, in trying to revolve, will press the foot into closer contact with the ground, and thus increase the braking effect. For the same reason the braking pressure is always automatically proportioned to the load, and it is claimed that its effectiveness is adjustable so that it may be set either so that it brings the vehicle slowly to a stop or pulls it up quickly.
Other Patents of Interest.
J, H. Schofield makes a brake lining' by using. perforated sheet metal as a basis, threadire, it with asbestos to such an extent as practically to cover the surface and subjectine. the -whole to pressure in order to flatten the asbestos sod form of it a continuous layer. His process is completely described in specification No. 189,858.
A neat and simple form of ratchet gear or sprag for fitting to the rear wheels of motor vehicles, in order to afford means of preventing backward running, is described in specification No. 189,914, by W. J. Dickinson. The ratchet lever is twoarmed, and has one arm engaging with a slot in the coupling, rod from the control lever in the cab, so that moving that lever in one direction lifts the ratchet entirely out of engage:: ment, whilst putting it over to the alternative position allows the ratchet lever to rest on the top of the teeth of the ratchet wheel, the slot in the coupling rod being long enough to allow of the ratchet and teeth engaging when required, as when the vehicle begins to run back.
It is interesting to note, following our recently expressed remark on this page anent the desirability of :fitting some form of servo brake on commercial vehicles, that specification No."199,947, by A. E. Bouvier, describes a brake of that kind which is specially designed for use on heavy vehicles. In this particular design, the power of the engine is usOd to provide the braking effort. Thu layshaft of the gearbox drives the. casing of a planetary gear, of which one sun wheel is coupled: to a small brake drum, and the other to a shaft on which is a_ lever whicli is connected to the main brake-operating, gear." The.small brake pulley is held by the driver, while he presses. the usual brake pedal or operates the side brake lever, and the immediate effect is to set the differential gear in motion and
transmit the engine power to the main brake. • • The De Dion-Bouton patent, No. 183.452, describes a detail of a brake gear which is mounted with one of the operating shafts locaAed at one end on the frame .and at the other on the casing of the propeller shaft, and shows how the ill-effect of the oaiillation of the latter may be eliminated.
E. S. Ross and another describe, in specification No. 189,621, a method of diminishing the danger which arises when a pneumatic tyre bursts while the venicle to Which it is fitted is travelling at high speed. They fit the wheel with an extension of the rim of such a shape that when the tyre does deflate the wheel does not. fall the whole .distance.
The carburetter which is described in specification No. 189,887, by G. Constantinesco, has the flow of 'fuel through the jet controlled electrically, The jet is in the base of the fuel chamber and is closed by means .of a tapering needle. A solenoid, whicla is energized by the magneto, is mounted on this needle and operates so that the jet is closed when the
ignition cut, off. 'Priming, as for starting, may be effected limy passing a current from a battery through the solenoid.