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A Two-Circuit Braking System

12th July 1957, Page 66
12th July 1957
Page 66
Page 66, 12th July 1957 — A Two-Circuit Braking System
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A BRAKING system intended for r-i• tractor-trailer combinations is shown in patent No. 776,725. (Maschinenfabrik Augsburg-Nurnberg A.G., Nurnberg, Germany.) The chief

feature is the use of both compressed air and hydraulic mechanism, the two being interconnected so that failure of the air system automatically applies the hydraulic brakes.

In the drawing, the front brakes (1) are worked hydraulically, whilst the rear ones are applied by a compressed-air

cylinder (2). The hydraulic mastercylinder (3) is strongly biased by a spring into the " on " position, but normally the spring is inactive, its force being opposed by that of an air-operated servo-piston (4). Also in the air system is a trailer-brake pipe-line (5) which is controlled by a valve (6).

When the pedal (7) is depressed it allows air from the reservoir (8) to operate the rear brakes; it also moves the trailer-brake valve into a position in which both the trailer brakes and the servo-cylinder are vented, thus bringing front brakes and trailer brakes into action.

Should the compressed-air system fail or the trailer break away, the vehicle would be stopped by the application of the front brakes. They can, however, be released by pressing an emergency escape-valve (9), but thereafter, only the hand-brake would be effective.

A HEAVY-DUTY VEHICLE PATENT No. 776,775 shows a vehicle for transporting loads of the order of 50 tons, and in particular of the type having an eight-wheeled bogie at the

.rear, (Scannmell Lorries, Ltd., Tolpits Lane, Watford West) The vehicle is novel in the fact that it has two separate engines, each with its own gearbox. Each unit drives one side of the eightwheeled bogie, making all eight wheels powered.

The specification illustrates the complete vehicle, but the adjacent drawing shows only the bogie driving arrangements. From each gearbox runs a pair of propeller shafts, one (I) at a .) low level to drive the leading half bogie and another (2) which passes over the top of the leading axle to take the drive to the rear one.

At full loads, both engines would be used separately, but when running light the two gearboxes can he coupled to allow one engine to provide all the power. To provide a good view down each side of the vehicle, there is a separate near-side cab 'and an off-side one, with the engines located between them and covered by a bonnet.

To permit detachment of the inner wheel of each pair, a davit (3) is provided, with which the wheel can be hoisted out through a trapdoor as indicated at 4.

PREVENTING BRAKE SURGE A FORM of vacuum brake disclosed in a previous patent numbered 694,582 had as its object to give the driver a good sense of feel of the force he was applying. Now, in patent No. 775,321, the same brake is shown with certain modifications aimed at preventing surge in the system when the brake is applied. (Girling; Ltd., Kings Road, Tyseley, Birmingham.)

ALL-RUBBER SUSPENSION FOR HEAVY VEHICLES

A SUSPENSION system for heavy 1-1. vehicles, employing rubber for the resilient medium, is shown in patent No. 776,620. Although intended chiefly for trailers and semi-trailers, it is said to be,suitable also for driven wheels whether steerable or not (Cranes (Derehann), Ltd., South Green Road, Dcrcham, Norfolk.) To the axle is connected a radius arm (1), its bulbous end being contained in a housing (2) fixed to the frame. The housing is split and bolted together and is fitted with a rubber lining to grip the bulbous portion. Steel sandwich plates (3) may be incorporated, the number of them governing the degree of resilience of the joint. When the unit is deflected under load, the rabbet. is

corn pressed at one corner and allowed to expand on the opposite corner.

The arrangement is claimed to be much lighter than a Comparable steel springing system, has nothing to wear and considerably reduces the• unsprung weight of the axle assembly.

AN AUTOMATIC BRAKE ADJUSTER

AN automatic take-up for excessive brake clearance is revealed in patent No. 776,849. (S.A.D.U.B., 104 rue d'Angleterre, Tanger.) The two shoes are interconnected by a non-return friction member consisting of a pack of spring-blades in a tube. The blades will move freely outwards, but bite if a return stroke is attempted.

A COMPOSITE BRAKE ACOMPOSITE brake utilizing both drum and disc surfaces is disclosed in patent No. 776,743. (Bendix Aviation Corp., South Bend, Indiana, U.S.A.) The disc portion is primarily energized, and its attempted rotation and consequent pivotal action used to expand the peripherally faced portion.

A double-ended hydraulic cylinder (I) pushes an arcuate member (2) in one circumferential direction and a second member (3) in the opposite direction. A number of ball and ramp combinations, as indicated at 4, translate this movement into axial thrust and so bring the disc surfaces (5 and 6) to bear.

The anchors of the arcuate members are so located that the torque generated by the disc action forces the peripheral• facing (7) outwards into braking contact with the drum. The arrangement works in either direction and is largely self-energizing.

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