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SERVO-APPLIED AUXILIARY BRAKE. SHOES.

9th October 1928, Page 32
9th October 1928
Page 32
Page 32, 9th October 1928 — SERVO-APPLIED AUXILIARY BRAKE. SHOES.
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Which of the following most accurately describes the problem?

A Résumé of Recently Published Patent Specifications.

MWO very interesting brake arrange ments are shown in speciticatione. Nos. 296,463 and 296,389, both by A.C. (Acedes) Cars, Ltd., and Herbert W. Pitt. In the first-named specification, a brake is described which has two sets of shoes acting in the same drum, one of which it anchored in the usual matner to prevent it from following the direction of the drum. This we hale called the fixed brake, for clearness. The other brake has no anchorage, so free, when brought in contact with its drum, to follow it until a projection from it comes in contact with an arm projecting from the cam of the fixed brake, its contact with this arm being its only anchorage.

It will be seen from this that, when the floating brake is applied, it tends to revolve with its drum, so pressing Lard against the arm of the cam of the fixed brake, thus causing it to be applied without any force from the driver other than that used to apply one brake. By this means two brakes can be applied by a force which would otherwise be necessary for the application of one brake only.

The second-named specification, No. 296,389, is also very interesting. In this arrangement, two brakes are made to act in the same drum, both of which are anchored in the usual manner and 848 have cams of ordinary construction to expand them. The novel feature lies mailily in the fact that both shoes are provided with auxiliary shoes which are free to move in the direction in which the drum is travelling when brought in contact with the drum. Both these auxiliary shoes are mounted :en a number of rollers, this arrangement. being made to allow their movement to be unimpeded.

Both the cams are provided with extending arms, against which the auxiliary shoes bear in their effort to follow the drum. In doing this they assist in the rotation of the cam, thereby causing a servo effect. Unless we are mistaken, we have an idea that we have seen something like this in the Girling brake.

The Lubrication of High-speed Gears.

.MEANS which tend to the better lubrication of high-speed gears forms the subject of specification No. 292,540, by the International General Electric Co., of New York, In this specification, it is pointed out that oil is the only lubricant that can safely be -need to lubricate gears that revolve at very high speeds, as, with thicker lubricants, such as grease, there is not time foe the lubricant to enter the teeth of the revolving gears. Even with oil, it is pointed out that there is a danger of the oil being thrown nut from between the teeth by centrifugal force owing to the high rate of revolution of the gears. The present invention consists of a guard which partly surrounds the gears so that the throwing out of the oil is tendered impossible.

The figure we have selected represents a guard that will act equally well while the gears are revolving in either direction. It will be seen that there is an interruption on the guard at its lowest part—this is said to allow oil to enter between the teeth, so when once in it is carried round without any way of escape until it meets the teeth of the meshing pinion, where a pressure of oil is produced, which Is claimed to be beneficial in preventing metallic contact between the teeth cf the gears.

A Towing Brake for Trailers.

A COMBINED tow-bar and brake

actuating rod is shown in specification No. 295,883, by the Eccles Motor Caravans, Ltd., and W. T. Riley, both of Birmingham. A cylinder contains a sliding rod which forms the pull bar of the trailineerrangement. This sliding bar is provided with a collar attached to it in the centre and has a strong spring, as shown on the left, which acts to thrust the bar backwards, so applying the brake by means of the lever shown and the flexible cord. Normally the brake is on, but so soon as the bar is pulled by the tractor the front spring is compressed, the cord is so allowed to slacken and the brake to come off, the front spring acting as a means for operating the brake automatically and at the same time affording a spring to relieve the pull bar of shocks. Should the trailer press hard on the tractor as on very steep declines, the rear spring, which is lighter than the front one, will

An Autovac Improvement.

THE name Joseph Higginson, already

known in Connection with the Autovac, appears in specification No. 295,818, in which it is pointed out that, with the ordinary Autovac where. the fuel is drawn up by euetion into au intermediate, apparatus and delivered to the engine by gravity, when the engine is idling there is a high degree of vacuum in the induction pipe and ivhen such vacuum is applied to the intermediate apparatus, a vaporization of the fuel takes place; the fuel being drawn into the induction pipe, so enriching the mixture passing to the engine,.

To overcome this is the main object of the present ineention. The suction elbow of the Autovac is provided with a valve (A) which usually lies on Re

seating (B), but when normal suetim takes place it rises until it comes into contact with the projecting forks of the spring-controlled sleeve above it. The gaps between the forks of the ends of this sleeve allow sufficient suction for normal conditions of engine speed, but should the speed be diminished to mete idling by the closing of the throttle and the vacuum rise accordingly, the suction will cause the sleeve (E) to rise, thus allowing the valve (A) to come in contact with the seating (C) to close all but the small opening (D) arid thus to limit the vaporization that can take place while idling.


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