MOTORING

Gisborne Times, Volume LXVIII, Issue 10752, 24 November 1928, Page 11

MOTORING

C LETCH LESS CAR. NEW ENGLISH INVENTION. AUTOMATIC VARIABLE SPEED TRANSMISSION. OBTAINS WONDERFUL RESULTS

LONDON, Sept. 27. Has a- really gearless, clutchless motor-car come at last? The answer is, Yes. .T. H. Robertson, after five years’ work and at the cost of many thousands of pounds has perfected an automatic variable speed gear; transmission. A representative of The Christian Science Monitor was taken for a drive by Mr. Rcu bit son and was allowed to drive the ear himself. Driving is reduced to the action of one foot on either accelerator or brake pedal and the hands on the steering wheel. There is in addition a small lever in the centre of the floor-board which is used to put. tho c-ar into reverse and for other purposes which will be explained Inter CAR ACCELERATES RAPIDLY.

The engine having been started in the. usual’way the driver depresses the accelerator pedal and the 1 car glides away without the semblance of snatch. If the pedal Ls depressed rapidly and fully the ear still moves off perfectly smoothly but accelerates rapidly. To stop, the foot is shifted to the brake pedal, which pulls up the car according to the degree of pressure exerted, the engine then turning over in neutral. This ease of control must l«o experienced to he realised and the smoothness and rapidity with which the ear moves off from a standstill leaves one almost breathless with wonder. During this test-drive the car was held up in a, traffic block next to a large powerful ear.

SURERI SI NO G ETA WAY. On the release signal being given by the traffic policeman the driver of the big ear must have been surprised at the way Mr. Robertson's ear shot, away without apparently touching any lever or control. The small central lever, which is termed the “joystick,” is used fl; to restart the engine while the car is running; (2) to coast down incline with engine stopped and restart engine by pushing the leyer forward; (3) secure a free engine; (4) change the characteristics of automacitv of the variable, gear; (») change down to any ratio when going down hill and using the engine as a hi alee; (6) put the car into reverse with the same automatic variable speed and noiseless operation.

RUNS AUTOMATI C’A LLY. The. engine of the five-year-old eatin which the “.Monitor” representative drove had, Mr. Robert soil said, done 25,000 miles without decarbonising, yet it van perfectly without a trace of “pinking.” This, he< said, was duo to the fact that the engine was always running automatically at its proper speed in ratio to its load. It is never overloaded at low speeds on top gear. No matter how had the driver may he the system will not allow of a starting shook and picks up its own ratio whatever he may do in the way of depressing the padftl. The gear is suitable for Imilding into any motor vehicle, whether a 4-ton lorry or 7-li.p. rnn-nlwuit. The number of parts is small and the whole mechanism extremely simple. A number of motor-car manufacturers have already ordered sets to fit to chassis with a. view to drastic trials.

' ROBERTSON DEVICE TESTED. DETAILS OF DESIGN. Tho “Autocar” contains particulars and a description of actual experiences with the Robertson gear, of which it publishes also a line drawing which indicates that it will fill less space, than the ordinary gear-box does, as well as thing simpler. The “Autocar” points out- that there is no real reason to believe that the friction gear will he unsatisfactory, as, in fact, it is already largely used, being part of the equipment of all mechanically-propelled vehicles which transmit their power through wheels. The Robertson automatic variable gear appears to have been scion tificially designed, and therefore should work perfectly. Tho friction gear is of the cone type, the face of tho fly-wheel being slightly coned, while that of .the propeller shaft is inclined forward, and carries a plate or disc which is also slightly conod to match the pace of the flywheel. The front end of the propslior shaft can he moved by a control, and the disc or hollow" cone which it carries has on its inner edge a. strip of friction material. When the hollow cone fits exactly on the flywheel cone, it resembles a cone clutch, and the propellor shaffc, which can be moved up and down by its control, is exactly in line v.-ith the flywheel centre or crankshaft. end

VARYING RATIOS. Tliif? is the direct, drive of the Robertson gear, and so far there is nothing new in it. Reduction in the drive is obtained by moving the end of tlio propeller shaft with the hollow ‘‘one upwards, making a line contact fcictween the flywheel cone and the ring of friction lining in the hollow cone, so that the flywheel resembles a bevel pinion, and the hollow cone a, crown wheel, both, of course, without teeth. The higher the hollow cone is moved the smaller the bevel pinion becomes, that is, the greater the reduction in the drive. Actually, from direct drive, or one to one. a reduction to about four to one may lie obtained without difficulty, and as the reduction may be to any degree within these limits, a ear with a, final drive reduction of, say, five to one, has an infinitely variable gear -within thu limits of five to one on top, and 20 to one on bottom. The gear is described as “foolproof” "and the inexperienced driver cannot destroy it by allowing slip to take place when starting from rest. Even on a really steep hill, on which an expert driver with the older types of friction drive might grind a flat on the friction disc, the Robertson gear cannot be so mishandled, as a disc clutch is interposed between hollow cone and propeller shaft, and must slip before the friction drive. Furthermore, it is the friction drive which engages this clutch, 'and not the driver. Tile action is obtained by the mechanism, which also varies the gear ratio automatically. The coned face of the flywheel is'in reality a separate part, and by the action of a form of centrifugal governor within the flywheel, it is made to slide out away from the flywheel proper as the engine speed increases. This has the fleet of moving the hollow cone ; downwards, so raising the gear ratio. The outward movement of the flywheel cone naturally forces it against the bollow cone, thus increasing the pressure on the friction surfaces, and it also pushes the hollow cone against the disc clutch, so that the drive is, transmitted to the propeller shaft.

GEAR IN USE. Tha operation of driving with this gear is described as simplicity itself. Normally, when the engine is not running or is only idling, the hollow cone is in its highest position, giving the lowest gear ratio, but there is no pressure on the disc clutch, and therefore the car remains at rest, As soon as the accelerator is depressed,

the clutch is automatically engaged, and the car mores off. the gear ratio rising as it gathers speed, that is as the resistance to movement is overcome. To slow down it is only necessary to release the accelerator, then the gear ratio gradually falls, and as tin* brake is applied to bring the car to rest the clutch disengages. On a gradient the gear ratio gradually falls as the • esistauce increases.

This, it is stated, was repeated!\ observed on hills with gradient of runin 4i, one in seven, and other exceptionally steep hills near London Several starts were made on the steepest parts, a feature being the smooth operation. If a rather faster ascent was required, it was only necessary to use the hand control to lower the gear ratio slightly, more than it was set by the automatic control. In traffic also the hand control could !fe used. to give a lower ratio than was demanded by the engine, in order to gain rapid acceleration. Nevertheless. acceleration by means of the automatic control is described as good. The gear was tested on an old Gwynn? ear. and as far as could be judged was not noisy.

PNEUMATIC TYPES. NEW T’IMXCTI’LE IX DESIGN X<-w .principles in tbe design of pneumatic tyres are claimed to be features of an. invention by Mr. E. P,. Killen. of London. The invention relates to a new cover, tube, run and wheel. The tyre is oval in section and designed for low pressure of air and to carry overloads. The outer cover has three tread elements of different widths, brut the same thickness, all integral and combined with the cover. As each tread is worn out the one beneath takes up its work. An extra cord construction can he introduced into the third or inner tread like a liner, but this can be torn away if necessary for retreading. Non-skid grooves are continued down through the first, two treads, and it is claimed that the life of each tread is front 10,000 to 15,000 miles on English roads. It is also claimed that the triple tread is a simple gattgo of correct inflation ns the distance from the edges ot the different treads to the road will sul-fic-ientlv indicate the correct inflation of the* tyre. Strengthening ribs protect the* side wall against damage. The heads of the tyres are wide apart and the rim forms a deep well between them enabling the tyre to ite mounted or detached easily. The tube in us? would be kept cooler, as much of it is tit contact with the metal rim, and not with the cotton and rubber cover, and the heat would. Therefore, ho carried away more efficiently. The cover is relieved of considerable stress under load, as the tube transmits a share to the rim. Different widths of tyres and wheels are interchangeable, while the. one-piece rim can he manniactnred cheaply, as it is light and of simple construction, and even unskilled motorists could work rapidly and easily on it. The increased well space in the rim affords increased air space in the tyre and easier tiding. lit addition it is claimed for the new tyre that thorn are five special contributing factors to the cooling ol tlie tyre—the non-skid tread with its deep grooves; thp large area, ol tube in contact with the metal rim; the Lust, that the oval section of the tyre provides that for any given diameter on tiie tread the inner circumference of the. tyre stands farther away front the outside of the brake drum than would he possible with a round section tyre, while asbestos washer are, introduced between the drum and the wheel,, and air is passed through holes near the rim by four small air scoops and helps to carry away the brake heat. Tito new type of wheel and tyre is claimed to cling to the road without bouncing unless overheated and gives considerable deflection vertically. It is. in fact, suggest'd that with those tyres the chassis springs can lie rendered almost, unbreakable by the addition of one or two extra leaves, so that they would only he called upon, to function under extraordinary conditions or heavy loads. There, would he no necessity to slow down for pot holes, as bounce would he eliminated and the l practicable speed would be increased. The easier fitting and management of the lyres would make for improvement also in tyre service. It is calculated that 11 sectional widths of ivres would b? sufficient.