vv Brakes for AutomaticCoupling Semi-Trailer
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terference with fully automatic ding is caused by the fitting of hydraulic semi-trailer braking reduced by the Primrose Third ., Ltd., Clitheroe, Lancs.
iydraulic system and master are carried on the semi-trailer orccarriage, whilst the actuating m is fitted to the tractor. A servo on the tractor operates a king about a fulcrum point level top of the chassis frame. Above :ny this point two rods arc to the lever which, when it is ulls on the lower rod and pushes per one.
)wer rod is connected to the nech a n ical semi-trailer braking Nhich passes through the centre wupling turntable. whilst the d actuates the master cylinder. open U-shaped member on its
which, when the tractor is
coupled to the semi-trailer, contacts the push-rod for the master cylinder. This unit is mounted on the off side of the lower stationary half of the semi-trailer turntable.
From the preisure outlet of the master cylinder a copper pipe .transfers fluid to a three-way connector attached to the front of the lower turntable. From there, fluid is taken through a flexible pipe to a similar connector on the top half of the turntable and thence through rigid piping to the wheel cylinders. The :lexible piping allows for relative movement between the turntable halves.
Although a vacuum servo is used a1 present, it would be possible to employ an air-pressure servo after reversing the position of the actuating rods on the servo lever. The mechanical braking system is retained to allow a tractor modified for hydraulic braking to be used with an unmodified semi-trailer or vice versa.