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A Friction-restricted Differential Gear

31st December 1948
Page 52
Page 52, 31st December 1948 — A Friction-restricted Differential Gear
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A Resume' of Recently Published Patent Specifications

THE usual type of differential gear permits the drive to be completely lost if one of the wheels should spin, and this proves a nuisance on slippery ground. To reduce the tendency to slip, without departing from the true differential principle, is the aim of an improvement shown in patent No. 606,782, by R. G. Letourneau Incor

porated, Peoria, Illinois, U.S.A. , In this scheme the differential pinions are fitted with a frictional device which, by creating a drag in the action, permits of only a moderate torque to the wheel which would otherwise spin. Referring to the drawing, the friction members take the form of largediameter discs or rotary heads (1) which are integral with the bevel pinions (2). The discs are journalled in clamped rings (3) which, owing to their large area, provide considerable rubbing surfaces, and are thus particularly useful at the high speeds at which the pinions revolve during wheel spin.

The patent covers also the brake mechanism shown at 4; this comprises a contracting band surrounding a drum attached to the differential cage.

A PEDESTRIAN-CONTROLLED ELECTRIC TRUCK

AN electrically driven vehicle of the pedestrian-controlled type is shown in patent No. 606,857, by W. Reeves, and Electruks, Ltd. 8, Fitzroy Road, London, N.W. The main subject of the patent is the arrangement of the suspension system.

Dealing first with the general layout, the chassis is made of rectangularsection cold-drawn steel tube, joined by cross-members of similar material. A single front wheel is used, carried in a fork (I) and mounted castor-fashion; steering is by a hinged handle (2). The handle also cuts off the current and applies the brakes when moved into its uppermost position. Batteries are carried on each side of the motor (3) and the latter drives a two-wheeled rear B18 axle via a propeller-shaft provided with universal joints.

The suspension system is novel; a pair of leaf-springs (4) are employed. but they are disposed in an up-ended position, being rigidly clamped to the axle-casing and pivoted at point 5 to the frame. A measure of fore-and-aft resilience is thus obtained, which is intended to soften shock loading caused by acceleration.

ONE-CHAMBER TYRE WITH SAFETY DEVICE

PATENT No. 607,354 comes from Australian Steel Split Pulleys Proprietary, Ltd., Homebush, near Sydney, and shows a tyre having no inner tube, the outer cover alone forming the inflatable member. As a precaution against sudden deflation, the tyre is provided with an.emergency rim to support the wheel in the event of a puncture or burst.

The drawing shows how the tyre is provided with an inner cushioning tyre (I) made either of solid rubber, or hollow as shown. The rubber portion is a complete ring, but its supporting rim (2) is made in segments bolted to an inner rim (3). The latter member, in conjunction with the outer rim, forms the means for sealing the large air-space, which is filled through a conventional tyrevalve (4). To permit of assembly, the outer rim is divided into two rings, one of which is detachable. A ring of short security bolts enables the two rings to be tightly clamped together to form an airtight seal, The inner tyre may be filled with air, or some liquid having a low boiling point, so that when work-heated by load it will expand into vapour and create a pressure.

A SELF-OPERATED TIPPING LORRY TAILBOARD

THE tailboard of a tipping lorry has usually to be released and lifted by hand, but patent No. 607,480 shows a

device which performs this duty automatically when the body is tipped. The patentees are John Laing and Son, Ltd., and J. Paxton, both of Mill Hill, London. N.W.7.

In the drawing the tailboard is hinged about point 1 and is held in the closed position by a latch (2). The latter member is conneeted by rodwork to a bell-crank (3) which normally makes contact with a stop on the chassis frame. As the body lifts about point 4 the bellcrank is freed, and a spring then pushes the latch clear of the tailboard. When the body returns to the normal position, the reverse action occurs, and the latch is brought back into action.

A QUICKLY ATTACHABLE TOWING GEAR PPARATUS for towing disabled vehicles is shown in patent No. 607,449, by L. Newman, and Ernest Lake, Ltd., Dunmow Road, Bishop's Stortford, Herts. The subject is a quick-acting clamp for attaching a drawbar to the front axle of the toed vehicle.

In the drawing, I is the front axle, with the clamp in position. A pair of vice-like jaws is drawn together by a bolt (2) which clamps them onto the axle, whilst a packing screw (3) can be adjusted to give a parallel grip; the unit resembles, in this action, a toolmaker's clamp.

The jaw assembly is pivoted horizontally at 4 and vertically at 5, .so as to provide a universal movement, whilst the front end (6) is adapted to suit the tractive unit. An important feature is that the clamping screws, being positioned well below the front axle, permit of ready access for adjustment.

The particular method of clamping • the jaws of the tow bar enables the device to be fitted to any type of front axle in a matter of minutes. To ensure the utmost safety, the provision of some form of locking device for the clamping bolts would appear to be necessary, together with a means for keeping the jaws of the clamp parallel. •

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Locations: Peoria, Sydney, London

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