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GATE CHANGE FOR EPICYCLIC GEAR.

31st July 1923, Page 30
31st July 1923
Page 30
Page 30, 31st July 1923 — GATE CHANGE FOR EPICYCLIC GEAR.
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Which of the following most accurately describes the problem?

A Résumé of Recently Published Patents.

IA/E FIND ourselves in entire agreement with L. H. Hounsfield when he says in the course of specification No. 199;234, which refers to a design of gate-change control for an epicyclic gear, that "it will be more convenient to describe the action of the mechanism after the drawings have

been considered. , ." Not that we regard the mechanism in itself as complicated, but because it doesnot lend itself. to simple explanation without fairly explicit illustration; what follows must, therefore, be read in conjunction' with the' accompanying drawings.

It. is apparently the intention of the inventor so to arrange the control of an

• epicyclic, chamge-speed gear a a motorcar that its mode of operation will approximate very closely to that -o.f an ordinary gearbox, with the idea that a driver; accustomed to the one, shall feel himself readily at home on the other. He therefore so arranges the mechanism of this device that, for the purpose of changing gear, the familiar operations of declutching, moving a lever through a gate, and re-engaging . the clutch, shall be performed, notwithstanding that as a matter of .fact, these operations are only apparent, as, for example, there is really no clutch to disengage or engage.

In the drawings, mechanism for a gear affording two speeds forward and one reverse is represented, but, for the sake of clearness, only those parts required

. in connection with the top speed are shown. To engage this gear, the pedal is depressed, moving ferward the lever (C) and pulling on the end (M) of the rocking lever (J). This lever. cannot, however, swing -about its proper fulcrum (K)—en the lever 0—because rearward movement of its lower end (L)is prevented by the stop (Q), against which the top-speed clutch lever (P) is resting. The fulcrum (K), therefore, moves forward, extending the clutch spring (8), and earrying with it the --change-speed, lever (0), until the lastnamed reaches the end -of the gate, which limits the movement of the pedal. The nextAoperation is the perfectly natural one of moving the change-speed lever (E) into the top-speed slot in the gate, whereupon the catch (V) engages with the stop (W), and the lever (E) holds G in the forward position', into which it has been placed by operation )f the pedal. • The,. last-named is now released, whereupon the spring (8) contracts, drawing back the upper end (my of the rocking lever (J), which must now swing about its proper fulcrum (K), bringing forward the lower eud (L), and engaging the top-speed elutth of the epic.yclic gear by means of the lever, (P). The stop (B) to P prevents the spring (8) from giving a permanent thrust on the clutch mechanism after engagement,

-Other operations of the gear are performed in a manner equally like to those of an ordinary gate-change mechanism.

The same inventor describes, in No. 199,231, a priming device. A. small chamber is provided whichmay be put into communication, first, with a fuel tank, and then with the engine cylinder, so that a measured quantity of fuel, for priming purposes, may be supplied. This alternative communication—and other functions in addition—are all per formed by the manipulation of one multi-ported cock, thus obviating the ssibility of two or more passages eing undesirably in connection at one and the same time.

Other Patents of Interest.

In shock absorbers which are dependent in the main on oil .dashpots and similar contrivances for their operation, effective action is more or less subject to the quality and condition of the fluid, since both affect its viscosity, on the degree of which the resistant powers of the mechanism depend. As a rule, the movement cf the oil, brought about under the influence of the shocks which these appliances are designed to abate, takes place through non return valves, which a r generally 'only adjustable to act correctly within narrow limits of loading. In the design which is patented by 0: D. North, and described by him in specification No. 199,172, the valve is controlled by springs in such a way that when the liquid in the

force it through a given orifice, the springs allow greater valve movement.

‘. Several modifications of the principal design are shown. In one -of the drawings this dashpot device is shown as part of aaeomplete springing system, in which each wheel of a car is, apparently, independently, sprung, by means of a coil spring valve. , The plunger or piston of the dashpot is on a hollow rod, into which the oil, with which. the apparatus is filled, passes on its way through this valve. The valve has no seat, as the term is ordinarily understood. It is, to all intents and purposes, a thick disc, supported, by springs at each side, and designed, when in mid-position, almost completely to block a circular orifice inside the hollow piston rod. This orifice is smaller in diameter than the interior of the rod, so that as the disc valve is moved to one side or the other of its mid-position oil can pass. The springs are designed to allow a certain movement of the valve under a given load, thus allowing the necessary movement of the oil from one side of the plunger to the other. Increased viscosity of the oil involves greater resistanoe to • movement of the spring plunger, increasing the force tending to. compress the valve spring, and, therefore;-enlarging the degree of opening.

.. An ingenious and simple. form of breather for a crankcase is described in specification No. 199,207. Its chief feature is the breather valve, which is of very than sheet metal (.005 in. is specified), and is centred on a pin. It, is timed to lift instantaneously when expulsion of air from the crankcase commences, and to close just as inhalation commences, thus preventing ingress. of dust and maintaining a partial vacuum inside the case. The patentee is B. 0. Jenkins.

S. J. Frost makes rather. ingenious provision for the lubrication, of the commutator on a Ford engine. A substantial funnel is used to facilitate replenishment of the crankcase ail reservoir. An internal podia in the funnel is pierced for the accommodation of one end of pipe, the other end of which opens into the commutator casing. Consequently, each time oil is supplied to the crankcase a small quantity is bound to find its way to the commutator via this pipe. The invention is described in specification No. 199,134.

F. W. Daniels encloses an electrical heating device in a thin closed tube which is inserted in the induction pipe.' By enclosing the wire in this fashion, it may be electrically heated to incandescence without risk of igniting the mixture which it is designed to heat,. (Specification No. 199,216.) A very simple form of hydraulic cluteh is. the subject of No. 199,224 (J. B. Gummersall). The hydraulic cylinders are embodied in a circular block. A sleeve on the block either entirely closes the cylinder ends, thus affording a direct drive, or, by partial throttling, varies the gear ratio.

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