A Mechanical
Page 74
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Servo Brake
rpHE brake described here is of the type in
which a servo effect is produced by the friction of a certain part of the mechanism against the brake drum, this contact being employed to operate a cam which forces the shots against the drum. The number of etha specification is 312,290, and it belongs to R. A. Crockett, of 85, Crosgrove Road, Walton, Liverpool. The specification does not make the action clear, but we presume that three shoes (5), (6) and (7) are employed, and that two brakes having three shoes each are placed side by side so. as to act within. the same drum. The shoes are brought into contact with the drum by means of cams (8), (9) and (10) formed on the boss of a lever (11), which rotates about its -centre (3) to cause the plungers to move outward. In the shoe (5) there is a segmental slot into which fits a pad forming a friction clutch, so that by a side movement of'this pad friction is induced between it and some revolving part, thus moving the lever: in such a way that it causes the plungers to move outward and so brings the shoes into contact with the drum.
A Self-energizing Hydraulic Brake.
THE hydraulic brake .described in specification No. 311,255 by G. H. Dowty, of "Lorraine," Wellington Street, Cheltenham, contains a novel feature, in that hydraulic pressure is gene rated in the mechanism contained within the brake drum. The specification describes the invention as being mainly useful for the brakes of aircraft, but that it may also be of use for road vehicles.
The shoes are of ordinary type, hinged at one end and forced apart at the other end by pressure from an hydraulic cylinder, the novel feature being in the means by which the re essure is generate& A rocking beam (A) is pivoted at its centre on a rigidly supported pin. At the ends of this beam are rollers which contact with a waved cam surface within the brake drum. This surface is only narrow and is by the side of the part of the drum on which the brakes act.
The cams, shown at B in dotted lines, are described as setting up an oscillating movement on the beam as the drum
revolves, thus actuating the two pumps shown, and consequently generating a pressure which is transmitted to the main cylinder used for expanding the shoes. A cam (C) operates a valve which releases the fluid so that it can operate in the main cylinder. AN shown, the cams (B) would not cause the. beam to oscillate, as two of them would come into operation at once; the specification is not quite clear on this point.
A Piston for the Morris-Commercial.
SPECIFICATION No. 312,108. of Morris Commercial Cars, Ltd., and W. W. Hamill, describes a piston which may be constructed entirely of aluminium or a light alloy, and which is claimed to be less susceptible to distortion owing to heat than when constructed on ordinary lines. The specification points out that distortion mainly arises from the gudgeon-pin bosses and the walls which support
them. It also mentions the fact that curving the walls inward in the neighbourhood of the bosses reduces distortion, but does not altdgether prevent it. The feature of the invention appears to be the use of walls curved inward, in conjunction with axially formed slots, The Suspension of Six-wheelers.
THE invention described in specification No. 312,475, by W. H. Kneller, of 12, Dupas Road, Croydon, relates to the even distribution of weight between the two bogie axles of six-wheeled vehicles.
It will be seen from the drawing that the ends of the, springs at each side which are nearest to each other are '
connected by means of a chain passing over a pulley or a sprocket wheel, which is supported by a bracket from the frame, thus allowing either axle to rise or fall on uneven ground. The bracket which supports the pulley may be used as the anchorage of a radius rod. So far as the compensation is concerned, a similar -effect'. is common practice in locomotive construction.