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A NEW FRICTION DRIVE.

13th April 1920, Page 26
13th April 1920
Page 26
Page 26, 13th April 1920 — A NEW FRICTION DRIVE.
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Which of the following most accurately describes the problem?

A Résumé of Recently Published Patents.

Th.e friction-driven commercial motor vehicle, although not unknown, is at least rase. Before the war there used to be a chassis of this 'type made in Liverpool, and,: although nothing has been heard of it lately, it was, neyertheless, quite a practical little machine, and may again come to the fore. There is also, in the G.W.B. chassis, which is employed to a not inconsiderable extent for commercial use, another example of -what the friction drive can do. These are both chassis of small load capacity, however, and we have to look to the farm tractor, n order to find an example of a friction-driven vehicle wherein the stre.sses are. Illsely. to be ,considerable.

The G.O.' tractor is the one which we Nave in mind. We are considering only chassis or tractorswhich are in use in

this country. The existence of .these machines is at least a proof that the friction drive is not altogether inadmissible for the purPoses■which we have to consider in thesis columns, and lends interest to thei invention, which is now made public in specification No. 139,249, by D. C. A. Bertelli and T. Dalzell.

The arrangement of the mechanism is nonsual, in that besides offering a direct drive on the top gear, the final drive' shaft is in line with the driving, or engine shaft-. A clutch_ of the -ordinary motorcar -type is provided, and is disposed within a recess in the flywheel,. ._ The latter is much larger in diameter, in proportion, than the clutch, so that there is left a.fairly wide face, outside the clutch, against which one of two friction 'discs bears. This we may call the intermediate disc. The other disc. bears against the side of the intermediate . disc, so arranged that the centre o-f i • its axis s in line with the flywheel. In all but the top direct drive, therefore, the transmission is,first, from' the face of the flywheel to the intermediate disc,then to the other disc, -which we may -call the final drive disc, and which is on, r. square on a shaft which is coupled to the propeller shaft of thp car. The .clutch: 48 _engaged. all the time that the car is being driven, but as its inner • member revolves on the spigeted eod of the shaft which carries, on a square, the final drive disc, it takes

no part in the transmission of the power except when on top direct gear. It ia,. however, fitted at. the rear with a set of claws, and the final drive disc carries, on its front face, acorresponding set, so arranged, that when the disc is pushed into its most forward position, the two: sets of Claws engage, _the friction discs being at the same time automatically thrown out of gear, and the drive converted to a direct one.

The final drive disc is slid to and fro upon its squared shaft in the customary manner 'across the face of the intermediate one, thus obtailifiii the changes in the gear ratio. The intermediate disc is.fastened to a short countershaft, which is carried in a peculiar bracket or fork. The two.prongs of the 'fork carry. ball or. rollet-hearings for the shaft, which may he slid longitudinally in them, so that

the discs may be separated. In the ordinary way they sre held in close contact by a powerful spring, which bears at one end against the outer prong of the fork, and at the other against a collar on the countershaft. The fork itself may also be moved in the direction of its stem, for the purpose of shifting the intermediate disc into or out of contact with, the face of the flywheel. A spring acts as the means of keeping the disc and flywheel in proper contact. As the fark is moved to separate disc and wheel, a. floating bell crank lever pivoted to ths.fork. and attached at its ends to the frame of the chassis and the.outer end of the countershaft respectively, operates to remove the intermediate disc from contact with the final drive disc, so that the separation of the three discs is simultaneous. By means of notches on the bosses of the various operating levers, this separation is timed to take place when the direct top gear is engaged.

Other Patents of Interest.

The object of the invention described in specification No. 139,299. by A. de Crminck, is that of providing against differences in the elevation of the rear endkof a chassis-when Subject to diffeient loading. The device to attain this end is described with reference to cantilever type springing. The upper ends of the front shackles of the spring are carried

M. an eccentric, the position of which may be varied by hand. For a heavy load, when the springs are highly compressed, the shackles are elevated; when the chassis is only lightly loaded, the reverse operation is effected. .

No. 139,300, by G. W. Pearce, is an improved design of-air pump for increasing the presture in a petrol tank. It is arranged so that the ports, etc., are automatically paced in proper relation one, with another by the movement • of the pump barrel into or out of convenient positions for operation. Provision is also made for immediate release of the pressure in the tank as may be 'required.

A couple of loops of spring steel, so. placed that they support the rear spring of a Ford car from the upper surface of its axle formthe Supplementary springing, which is the subject of a patent by A. E. Steel, and is described in specification No. 139,3042

A further invention in connection with aprons for the protection of the knees, of passengers on the upper decks of motorbuses and simi'ar vehicles is described in specification No. 139,312, by J. Bull. This particular arrangement is especially adapted for use in connection with those seats the back of which may be swung to and fro in order that the pass.enger may sit facing the direction of travel of the vehicle.

The springing which involves the use of two super-imposed q uatter-e I I iptis springs is the subject. of an improvement which is described in specification No. 139,324, by Waverley Cars, •Ltd. The two springs are made with a different camber one against the other, so that when the axle rises and falls under the influence of the springs, the shaft of thefl driving bevel pinion or worm Will always pOint mainly in the direction of the front joint of the propeller ahaft. In No. 139,394 W..1-1. Hingston builds upa .deuble banjo-type axle in an ingenious ' and apparently, . inexpensive manner by ,.bending: two steels channels and placing them together with the., edkeli'of-the 'flanges in contact. No. 139,425 is a. rather elaborate description of a three-wheeledd tractor, and :.particularly, of the main casting for

the frame of its chassis. .

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Locations: Liverpool

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