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Limiting Device for Self-adjusting Brakes

23rd April 1943, Page 34
23rd April 1943
Page 34
Page 34, 23rd April 1943 — Limiting Device for Self-adjusting Brakes
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A Rdsurne of Patent Specifications That Have Recently Been Published

• WHILST there is no doubt as to the W usefulness of a self-adjusting brake there is often a risk that the action may continue after the facings have been worn away and bring the naked shoes into contact with the drum. To prevent this is the object of a limiting device shown in patent No. 551,726 by Bendix Aviation Corporation, South Bend, Ind.,' U.S.A.

The drawing shows a view of the brake, looking at the bottom with a part of the drum sliced away. The adjusting spreader (4) can be lengthened by turning a nut member (3); this is provided with ratchet teeth which co-operate with a pawl carried on a link (1) and turns to adjust when the return movement becomes excessive. So much is, of course, well understood; the novelty of the present invention consists of a cam-face (2) on the adjusting member which, when moved to its outermost safe position, throws the link (1) sideways, so that its pawl can no longer operate the ratchet wheel. • The patent covers also a stop on the hydraulic expander to limit its total stroke; this is to prevent the driver from " pumping " the pedal.

To prevent over-adjustment, a thermo-sensitive bimetallic ;ever is provided. Distortioh of this occurs when the brake becomes excessively hot, with the effect that an element of lost motion is introduced to prevent further pick-up on the ratchet.

AUSTIN HUB REDUCTION GEAR WHEN a heavy vehicle W Is started on heavy ground. the use of full power in low gear imposes excessive torque stresses on the axle shafts and may often lead to fracture. To avoid this is the object of a hub reduction gear described in patent No. 551,580 by J. Haefeli and the Austin Motor Co., Ltd., Longbridge Works, Birmingham.

The drawing shows the hub (1) with the reduction gear attached to the ()inside thereof. A feature of. the design is that the outer dimensions of the gear are small enough to permit the detachable road wheel to pass over it without the need for dismantling. .

The axle. shaft carries ai its outer end a spur gear (3) which meshes with idler pinions (4). six in number, mounted on stationary pins carried on the axle casing. Meshing with the idlers is an internal gear (2) .formed in the bore of the hub. The total reduction is in the nature of about 21 to I, although it may, of course, be designed for other ratios.

A TWO-STAGE MASTER-CYLINDER REFINEMENT

A CCORDING to the Hydraulic Brake rICo., Detroit, Mich., U.S.A., it has been found that in a two-stage brake, namely, one having a large piston for bringing the shoes to bear, and a smaller one for the actual braking, the step produced by the meeting of the two cylinders has tended to hold trapped air. To avoid this is the object of a modified design of master cylinder shown by the above concern in patent No. 550.959.

This difficulty is overcome in a simple manner by arranging that the two cylinders shall be eccentric, so that their upper walls (I) are in line, the lower side having a double-depth step (2). By this means, there is no recess at the top side in which bubbles of air could collect.

PRODUCER-GAS PLANT WITH " READINESS " INDICATOR Tobviate the need for starting a producer-fed engine on petrol is the main object 9f. a schenie .shown in patent No 551,210, by W. Scott, 13, Edwardes Square, London, W.8. This inventor suggests the use of a blower.to raise the fire to the working state, in combination with an indicating device to 'inform the driver when the gas is rich enough for a certain start. In the example shown in the drawing, instead of using an indicator, the starter motor is automatically. switched on when conditions are right.

The outlet (8) from the producer branches into two pipes, one of which (9) leads to the engine intake, whilst the other extends to a suction fan (7). Both pipes are fitted with non-return valves to prevent backflow. The pipe (4) from the fan is open at its far end, but controlled by a throttle valve to maintain a slight pressure on the, pipe. From the pipe branches a small gasburner (5) which is located, under a sparking plug (6). The fan is electrically driven from the vehicle accumulator and when running operates also a make-and-break which maintains a continual spark at the plug points.

To start, the fan is switched on and the fire lighted. The gas, poor at first, will not be ignited by the plug (6). but when the required richness is attained, the gas will ignite at the burner. The flame then heats a bimeta:lic snapswitch (1) which flies over to the dotted-line position, breaking the fan cirenit and closing the starter circuit (10). Once the engine starts, the contacts (2) are automatically drawn into an 'inoperative position by engine suction, the action of which is slowed by the use of a vacuum box (3), designed to prevent any plucking action and consequent damage to the contact points.

Tags

Organisations: US Federal Reserve
People: AUSTIN HUB, W. Scott

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