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The Adams New Epicyclic Gear.

30th June 1910, Page 3
30th June 1910
Page 3
Page 4
Page 3, 30th June 1910 — The Adams New Epicyclic Gear.
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A novel form of change-speed gearbox lies recently been introduced by the Adams Manufacturing Co., Ltd., of 106, New Bond Street, W., for that maker's 16 h.p. taxicab and light-van chassis. In external appearance, the gearbox closely resembles one of the ordinary sliding-gear type, except thatthe gate-change lever is actuated by the driver's left foot instead of by his right hand. Closer inspection, however, shaws that the box contains a threespeed-and-reverse epicyclic gear, and that all the working

parts, including the brake blocks and much of their operating mechanism, are completely enclosed in an oil-tight and dust-proof easing. Simplicity of construction and ease of adjustment for the brakes have been most-carefully considered by the designer.

A leather-faced cone clutch is introduced between the engine and the gearbox, and, therefore, the crankshaft may be disconnected from the road wheels without the necessity for disturbing the running positions of the gears, although, of course, a free-engine position may also be obtained by the releasing of all the brakes.

The general lines on which this new epicyclic gear is built, and the position which it occupies in the chassis, are clearly shown in our illustrations. It should be noted that most of the transmission shafts are mounted either on ball bearings or Timken roller bearings, and that the gearbox is provided with oil glands for the prevention of leakage along the shafts. The gears are always in mesh, and each epicyclic train may be brought into operation by means of externally-applied balanced brake blocks.

The operation of the Adams gearbox may best be explained by taking each of the speeds separately, and, as the gear train for the second speed is the simplest, we will first proceed to explain its working. Rotation of the drum E, in which bearings are provided for the two planetarypinion spindles, is prevented bythe application of two brake blocks (F,). The second-speed gear, th,refore, is exactly like the back gear of a lathe : the primary pinion B on the shaft A meshes with the planetary pinion H and on the same spindle as the latter pinion is a smaller pinion (I) which transmits the drive to a fourth pinion (D), which last-named pinion is mounted on an extension of the tailshaft.

If, now, the brake shoes F2 be released, and the shoes F he applied, the brake wheel Y and the pinion Z rill be prevented from rotating within the box, and, as the primary pinion (B) continues to transmit power to the planetary pinions, H and U2, the drive will be transmitted from the last-named pinion, and the wheel X, to the stationary pinion Z ; the pinion X is thus compelled travel round the pinion Z, and, in so doing, it carries with it the drum (E) in the opposite direction to, and at a much slower speed than that of, the pinion B. The final drive of the low-speed epicyclic train is transmitted from the pinion I to the wheel D on the tailshaft, and, as there are more teeth on the pinion I than on the wheel X. it follows that the pinion D will be pushed bark in the opposite direction to the drum (E). but in the same direction as, and at a much lower speed than, the crankshaft.

The third speed, or direct drive, is obtained by first releasing the brake F1, and then applying the band brake R 1, which latter is anchored to the reverse-brake wheel (L); relative motion between the wheel R and the drum (E) is, thereby, prevented, and the whole, gear rotates as one piece, in the same direction, and at the same speed, as that of the crankshaft.

The reverse-speed gear's operation is very similar to that of the low-speed forward : the reverse-brake shoes (Fa) are applied to the rim of the wheel L—all other brakes being free—and the pinion R is, thereby, prevented from rotat

ing; the pinion J must then travel round the pinion R, ia the same way that the pinion X travels road the wheel Z for the low-speed-forward gear. It will be remembered.

that, in the low-speed-forward gear, the pinion D is pushed back in the opposite direction to the drum (E) because the wheel I has more teeth than the pinion X; in the reverse gear, the relation between the gears I and J, whose functions are exactly similar to those of I and X for the forward gear, are reversed, and, therefore the pinion D is pulled forward in the same direction as the drum (E) but at a slower speed. The direction of the drum's rotation, both for low-speed forward and for reverse, is the opposite to that of the crankshaft.

All changes of speed gear are effected by means of the left foot lever, the sole-plate of which lever, as may be seen in the reproduced photographs on the preceding page, has upturned side flanges which give the necessary grip for the sideways movement of the lever.

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