A SPEED-REDUCING GEAR.
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A Résumé of Recently Published Patents.
An interesting reducing gear of unusual type is described in specification No, 174,873 by C. H. Beasley, . it may best be described in connection with the accompanying illustration in which the driving, or high-speed shaft is that which appears on the left-hand side. It will be observed that the driven shaft is in direct line with the driver, and that both are journalled in the common easing which covers the reducing gear_ On the inner end of the driving shaft is a disc which has a sloping face, to serve as a rotary cam. The disc is supported in the casing by a row of balls which constitute a ball thrust bearing, while similar provision is made between the cam face of the disc and the intermediate member of the gear. This intermediate member is peculiar both in constitution and function, One face is. plain, except in so far as it is grooved to accommodate the halls of the thrust bearing; the other has a number of teeth cat in it, while the centre is formed as a spherical concave bearing to accommodate the end of a spindle which is centred in the driven shaft. There are keys secured to the extremity of this disc. The keys bear in slots formed in the main casing, and they are so arranged that, while they prevent the disc from rotating, they allow it complete freedom to oscillate, which it does under the influence of the rotating cam, acting through the me dium of the ball-thrust bearing. The disc is supported, for this oscillatory motion, by the spherical centre bearing. The driven shaft also carries a disc at its inner end, which, like that on the driving shaft, is supported on an annular row of balls. Its inner face, however, is parallel to its outer one, and is a plane at right angles to the axis of its shaft. On it are cut teeth which engage with those on the oscillating disc. One more tooth is cut on the disc on the driving shaft than on the oscillatingdisc.
The effect of this difference in the number of teeth in combination with the oscillatory motion of the central disc, is to cause, the driven shaft to revolve slowly, at a speed in accordance with the actual number of teeth employed. For example, in the drawing, there are 48 teeth shown on the driven teeth, with 47 on the oscillator. The ratio between the speeds of the two shafts is, in this case, 48 to 1. With 12 teeth on the driven disc and 11 on the other, the reduction would be 12 to 1, and so on. The same mechanism could be used as a multiplying gear by transmitting the drive in the reverse way, provided that suitiable modification were made in the design of the cam member.
The idea involved in the magnetodriving gear, which is described in N.
174,758, is so obvious—now that it has been pointed out—and the advantages derivable from the application so real, that one finds it impossible to avoid won dering why it was not utilized 10, 15, or 20 yeara ago. It seems particularly sur prising that Mr. F. H; Lanchester, who
is the patentee, has been so long in discovering it. Everyone par exemple is aware that, if the two portions of a universally jointed shaft are not in line, the angular -velocitiesare unequal, that A34 if one of them has a regular angular velocity, that of the -other+will be irregular, and vice versa.
Mr. Lan chester takes advantage of this irregularity, and, putting a Hooke's joint in the driving shaft of a magneto, deliberately sets the latter out of alignment with the main shaft in such a manner that the magneto shaft is given a higher speed, or speed above its aver
age, at the period when the ignition current is being generated and the primary break takes place. The advantage of increased speed of the armature at that period needs no demonstration.
Other Patents of Interest.
No. 174,789 describes a labour-saving device in connection with the towing of a disabled car. It is a connection for use between the rear axle of the towing and the front wheels of the towed car, which is devised not only to effect control of the steering of the towed car, but to apply a brake whenever the tension in the tow rope is relaxed. Two brake
drums are provided, one for each front wheel of the towed vehicle. The drums are designed so as to be easily attached to and detached from the wheels. Within each drum is an expanding brake, which is normally in operation, being held so by an arrangement of springs. -The towing gear is coupled to hubs mounted within the drums in such a way that as the tension is applied it releases tile brakes. The patentee is S. G. Mackaness.
The resilient wheel Which is described in No, 174,780, by J. Martin, is simple enough in design to be commendable almost from that point of view alone. The wheel is built of two discs, which are mounted on the hub, and formed, at their peripheries to accommodate the sections of a block tyre which is arch-shaped in cross section. Radial saw cuts are made in the disc, extending inwards from the rim, and so arranged that each block of tyre is between two such cuts. In principle, as the block of tyre takes the load its base expands and takes with it those portions of the discs between which it is held.
The auxiliary air valve which is described in Nu. 174,797, by T. E. Rees, takes the form of a strong intermediate flange, thick enough to accommodate a number of air inlets which extend from its exterior surface to the central opening, which is of the same size as the induction pipe. These air inlets are normally closed by spring-controlled ball valves. A gauge disc is located in the central aperture, through which the mixture passes on its way from the carburettor to the engine. This disc is so disposed that it may move in the passage under the influence of the engine suction. Protruding tongues on the disc engage with the ball valves to open them, and admit extra air, when the engine suction is excessive. An interesting type of self-lift gear for a tractor plough is the subject of No. 174,787, by J. Lowson. It is of the ratchet type, and is totally enclosed, being set in motion and liberated respectively by the withdrawal and insertion, into the casing, of a plunger, which is the only external moving part of the gear. Suitable connections are provided between this gear, which is mounted on the land wheel of the plough, and the axle of the furrow wheel, as well as to the pivot of the trailing wheel. Means are also afforded for adjustment of depth.
J. and F. Howard, Ltd., describe, in No. 174,855, a tractor drawbar which is is adjustable laterally, while the tractor is in motion, or, at least, without there being any necessity for the driver to leave his seat. The attachment is triangular in form, the implement being secured to the base Of the triangle, while the tractor is, to all intents and purposes, hitched to the apex. By means of a lever working in a ratchet, the shape of the triangle may be altered and the position of the apex is varied.
A carburetter in which the wick os surface evaporation principle is embodied is ti e subject of Specification No. 173,318, by J. A. Jackson and another. The liquid fuel is fed into a chamber
filled with absorbent material. Above this chamber is another, which is divided by... horizontal partition. Air enters the lower portion of this chamber, and is brought into intimate contact with
the fuel-soaked absorbent. It passes thence through a vertical tube, termed the primary mixing chamber, to which it has access through a number of small holes and a pad of "pervious material." It passes thence through a second series of holes into the upper part of the chamber, which is termed the secondary mixing chamber, and is there mixed with a further supply of air svhich enters under control of an auxiliary air valve.