AT THE HEART OF THE ROAD TRANSPORT INDUSTRY.

Call our Sales Team on 0208 912 2120

Girling Introduces New Brake.

25th November 1938
Page 46
Page 46, 25th November 1938 — Girling Introduces New Brake.
Close
Noticed an error?
If you've noticed an error in this article please click here to report it so we can fix it.

Which of the following most accurately describes the problem?

with Novel System of Shoe Mounting

TN any conventional brake design, the Irruption of the drum tends to carry one shoe away from the expander (whether of cam, cone, or any other form) and to force the other shoe on to the expander. Thus the former (or leading) shoe has, in some measure, a selfenergizing effect, whereas the trailing shoe resists the action of the expander.

Two consequences follow. If it be true that the, leading shoe is not overloaded, then it is clear that the trailing shoe is doing much less than it might. Equally, it is clear that the two facings will have unequal lives so that either time or material will be wasted.

To avoid these deficiencies, New Hudson, Ltd., Icknield Street, Birmingham, has developed a modified form of the Girling brake in which neither shoe trails and both have the self-energizing properties of an ordinary leading shoe. At the same time, all the usual Girling features are retained.

Thus, on a normal type of back plate there is a Girling wedge-and-roller expander mounted with sufficient " float " to ensure equal shoe contacts; there is also a Girling "clicker "-type adjuster which avoids the usual need to jack up the wheels when adjusting the brakes, Operating on the expander and the adjuster, instead of the usual shoes, there is a pair of shoe carriers. Each is a curved piece of L-section steel to which the expander imparts movement identical with that of an ordinary brake shoe. Lying around the circumference of each shoe carrier is a separate shoe, -faced with the usual friction material.

Separating the shoe and its carrier, there is a pair of rollers, one near each end. These are rollers in effect, but in shape more closely resemble discs. As the rolling motion they afford is through only a few degrees, much of the circumference on each side is cut away. The rollers themselves are hardened, as also are those parts of shoe and carrier on which they roll.

Principally for ease of assembly, each roller is retained by a stud (over which a;36

the roller loosely fits) and a spring of the circIip type, which, without distortion, cannot pass over the head of the stud. The shoe and its carrier are held together by a simple curved piece of spring wire, which passes under the two roller studs and over a third shorter stud fixed to the approximate centre of the shoe web.

. With this arrangement, it will be seen that the shoe can move circum ferentially around its carrier. The trailing shoe, when expanded to the drum, moves in this manner towards the expander, until its tip meets a fixed abutment which is attached to the back plate. The reaction is, therefore, taken by this abutment and not by the expander.

With the leading shoe, there is similar circumferential movement which is arrested when the shoe reaches a stop or lug on the carrier. The reaction is then transmitted through the carrier to the adjuster which, in a Gil-ling brake,

is also the pivot, of course. In an alternative arrangement, • the leading shoe is of normal pattern and only the second shoe is of the special type. This gives the same benefits when travelling forwards, but not in reverse.

Because both shoes operate as leading shoes, in that both have a selfenergizing action whilst neither tends to oppose the force of application, the total brake power is increased (it is stated) by 50 per cent.; alternatively the pedal effort can be reduced by per cent.

Another advantage is the ease with which the shoes can be demounted for refacing. All that is necessary is to release the spring wire and then to lift off the shoe. There is thus no need to interfere with the helical pull-off springs, which are attached to the shoe carriers.

The advantages afforded by this ingenious brake mechanism are manifold. In the first case each shoe performs an eatiaI share of the work of retardation—that is, the second shoe functions in exactly the same way as the first shoe—and, as a result, increases the efficiency of the brake, as compared with the type in which only the first shoe has self-energizing action.

Then there is the gain, mentioned earlier, accruing from the fact that the expander does not have to resist the tendency of the shoe to turn with the drum, a tendency which is acting against the pedal pressure, and accordingly creating an influence towards releasing the brake.

Thirdly, there is the important matter of facing wear. This also is equal, so that on the one hand life is lengthened and on the other both shoes fall due for refacing simultaneously.

Tags

Locations: Birmingham

comments powered by Disqus