1962 December, “Railway braking—progress and prospects”, in Modern Railways, page 400:
Fitting vacuum-operated two-cylinder block brakes is difficult: on hopper wagons very limited space is available for housing the complicated gear, and on 16-ton and 21-ton flat-bottom wagons, the brake gear is fouled by haulage and tipping equipment installed before the introduction of fitted mineral trains and often encroaching on the permitted available clear space between the inside of the wheels and below the axle.
