First-in-Britain Stopmaster brakes on ERF
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• The first production goods chassis in Britain to carry Stopmaster brake units is an ERF 64 (P) chassis with Ritemixer 5 cu. yd. concrete mixer, now in service with G. Gibson Readhnixed Concrete Ltd. of Gateshead. To ensure that the load could be carried within a 16-ton-gross weight, chassis weight had to be less than 4 tons. Light alloy mudguards, Goodyear Super Single rear tyres and a Centrax-Rockwell single-speed rear-axle were fitted and the Stopmaster brakes were decided on because, size for size, they are some 251b lighter than conventional wedge brakes.
Stopmaster brakes are made under licence from North American Rockwell by Centrax Gears Ltd. The sizes of those fitted to the Gibson machine are 15in. by 7in. all round. The main feature of the Stopmaster brake is that there are wedge actuators at both ends of each brake shoe and these are powered by a pair of air chambers. On the ERF the chambers on each brake are on separate circuits, fed through a dual foot valve so that if there is a failure in one system each brake will still operate. Following ERF practice, parking is through Westinghouse/MGM spring brake units, one actuator on each of the rear units being of this type.