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A LINE-DRIVE TRACTOR.

3rd January 1922, Page 28
3rd January 1922
Page 28
Page 28, 3rd January 1922 — A LINE-DRIVE TRACTOR.
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A Résumé of Recently Published Patents.

There has always been a peculiar craze amongst American tractor manufacturers for what is, over there, called the " line-drive " tractor. The fondness for this special type of machine has even been reflected from time to time in their technical Press. By a line-drive tractor is meant one which is controlled, not by means of levers and a steering wheel, but by a couple of ropes, which are arranged in such a mariner that their operation, in order to cause the tractor to stop, to move forward, to reverse, to turn to right or left, is similar to the manipulation of the reins when driving

• a horse. In fact, there are still a good many manufacturers in the States who,• apparently, believe that progress towards the successful tractor will be best achieved by a machine designed along these lines. • A typical example of this class of construction is indicated by a tractor, which is described in patent specification No. 171,421 by J. McLellan Lake. The tractor itself is a two,wheeled one, equilibrium being afforded, when it is in use, by the iraplernent, which is attached at the rear of the frame. The driver then sits on the Saddle, usually provided on a horse-drawn implement, and operates the tractor by means of ropes from that position. To enable it to be moved from place to place without of necessity drawing a•n implement a castor wheel attachment fitted with a saddle is provided: The accompanying drawing, which is reproduced from the specification, shows the machine in that form.

The arrangement of the components of the chassis present's no novel features. The engine and radiator are disposed in the customary position at the front, and the preliminary drive is transmitted, by means of a friction clutch, to a two-speed gearbox.. The latter drives by bevelled gearsto a cross-shaft, and it is in the• construction of the cross-shaft and drive that the interesting features of this in vention are found. There is no differential gear. The main. crown bevel merely drives a short shaft, to each end of which is attached the spider of an epicyclid gear. These spiders each support three sets of differential pinions. one of the three in each case is connected by a sun wheel, shaft bull pinion and internal 'gearing to one of the driving wheels of the tractor, the other two are in connection, each through its respective sun wheel to a brake drum. With both brake drums free, the gearing merely revolves idly and no power 15 transmitted. The ratio of the wheels in this epicyclic gear are such that when one drum is held, the drive is a forward one, with the other held it is reversed.

There is an epiOclic gear of this description on .each side of the main driving gear, and each is' controlled by a single rope, so arranged that, operating through a trip gear and rock shaft, a steady pull puts the reverse gear into motion. Slow release operates, by springs, to put the forward gear in motion, while a quick snatch and sudden release affords neutral. It will readily be understood how, by independent or Collective. operation of these two ropes the control of the tractor in the manner indicated is effected.

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Other Patents of Interest.

_Another tractor invention, this time from Italy, has to do with the arrangement of the suspension. It is of the type in which the final drive is by pinions and spur gears, which are bolted to the road wheels of the tractor. The live axle upon which the ; pillions are mounted is coupled to the rear axle of the tractor by means of a pair of links. l3y this means correct relation of the two gears one to another is permanently ensured. The suspension of the tractor chassis from the axle is by means of a pair of quarter-elliptic springs, . which are approximately of the same length as the link between the driving shaft and the axle, so that movement of the chassis on these springs is comparatively free. The patentee is "Ercolo Societa Anonima per la Costruzione e Commercio di Machine Agrieole e Trattori Brevitti Borello, and the number of the specification is 161,535.

The operation of the self-lift gear of a self-contained motor plough is the subject of No. 154,154, by E. Healer. In this case the main weight of the tractor is carried by two driving wheels, the small steering wheel at the rear serving to maintain equilibrium. In order to leave the plough free for work, .advantage is taken of the torque reaction of the tractor, the weights and moments of the various parts being such that when the control is operated so as, compare-.

tively suddenly, to reversethe motion of the tractor, the reaction Set up is suffi cient to overcome the resistance of the plough frame alone, but not the plough frame together with the steering wheel.

There is a ratchet connection between plough and steering wheel, placed .so that upon reversal of the direction of motion of the tractor the plough frame is either lifted or lowered between limits which may be set by the ratchet.

E. H. Develay describes, in No. 165,411, a change-speed gear, which is built up of epieyclic units. Each unit consists of a set of comparatively wide planetary pinions, the spindles Of which • are attached to the driving wheel of the gear. These planetary pinions are wide enough to engage with two gearwheels, which are Mounted freely upon the driven shaft.; one wheel is controlled by the brake drum, the other carries a pawl which is in engagement with a ratchet, which is fast on the driven shaft ; conse quently, when the brake drum is free.

the planetary pillions are merely carried round and transmit. no motion : when it is held, the power -is transmitted from the main driving wheel through the planetary pinions which roll round the brake-held wheel, carrying with them the other wheel, which itself drives the mainshaft by means of the ratchet and pawl. An ingenious arrangement of shock absorber is the subject of No. 153,569, by V. L. Jousse.

• No. 156,161 describes an arrangement of transverse springs which are coupled direct to the hubs of the road wheds. The patentee is R. L. G. Le Grain. • 0. D. Cars, Ltd., secure a gudgeon pin within its piston by splitting' it at each end, boring it to taper from each side and securing within it tapered plugs which are pulled together by single bolt, thus expanding the ends of the gudgeon • pin within the bosses in the piston. The specification is No. 171,504.

The same patentee points out in No. 1.71,505 that uneven operation of motorcar brakes brakes results from excessive torsion in the brake cross-shaft. The patentees improve matters by ensuring that,.the original effort is applied' in the eeiltres e the cross-shaft.

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