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HINTS ON MAINTENANCE.

16th September 1924
Page 27
Page 27, 16th September 1924 — HINTS ON MAINTENANCE.
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Which of the following most accurately describes the problem?

How to Get the Best Out of a Vehicle, to Secure Reliability and to Avoid Trouble,

561.—The Care of the Foot Brake on the Maudslay.

In the " A " type subvention Maudsla,y, the foot brake is very efficient providing that it is kept properly adjusted, but, unfortunately, this is not always the case, with the result that there is excessive wear on the friction linings of the brake shoes, and they have to be replaced more frequently than should be the case.

This wear may be due to one or more of several causes—faulty adjustment, scored brake drum, drum. running out of truth, inferior or unsuitable brake linings, distortion of one or both shoes, or faulty alignment.

The adjustment of the brake is not thoroughly understood by many drivers, and even by some mechanics.

Referring to the diagram, the winged nut (A) should be altered in conjunction with the setscrew. (B) to effect an adjustment. One spring (C) should exert a stronger pull than. the opposite spring (D), both shoes, therefore, being pulled towards C. The setscrew (B) should be screwed up sufficiently to keep the opposite shoe just clear of the drum (about in. is sufficient), whilst the winged nut (A) is adjusted to bring the front shoe into an, equivalent position to that of its fellow.

When adjustment is made to compensate for wear, both means of adjustment should be altered in the manner stated, thereby ensuring that the shoes grip simultaneously. The tube (B C) should slide quite easily over the adjusting rod (Al). This can be ensured if the rod be greased when assembled. The spring (E) should be of sufficient tension to release the drum immediately the foot is taken from the pedal.

In the case of bad scoring, the drum may be taken off and machined, providing the scores are not too

deep. Care must be taken to ascertain that the drum is mounted perfectly true with its bore. Thicker shoe linings must be used to compensate for the reduced diameter of the drum. Should it

run out of truth with its centre, re-turning must also be resorted to. Die-pressed linings have proved very satisfactory. They should be of 6 ins. radius, 3 ins. wide, I in. thick, and 9i ins, long, and should be secured with copper or aluminium rivets, care being taken to countersink the linings to suit the heads of the rivets. The radius mentioned is for a new drum, if the -drum has been machined the radius is naturally less.

Distortion of the shoes is usually caused through the brake being used after the lining is badly worn, thereby generating excessive heat. The only real remedy is the fitting of new shoes. Sometimes the brake drum is not in alignment with the shoes, with the result that the contact occurs over a small area only of each shoe—usually at its lower end. The fault may be due to tilting of the gearbox caused by the omission of the packing under the rear gearbox arms. Sometimes, however, it is caused by the holding-down bolts becoming loose, when vibration causes the arms to wear and allows the gearbox to drop slightly.

Finally, the greasers located at the top of each brake shoe should be filled and screwed down occasionally. Neglect to do this may cause the joints to bind.

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