IMPROVEMENTS IN SIGNALLING APPARATUS IN CONNECTION WITH VACUUM BRAKES FOR RAILWAYS
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by William John Adams at the Office
of the Commissioners of Patents on the 18th January 1883.
WILLIAM JOHN ADAMS of Queen Victoria Street in the City of London,
Engineer IMPROVEMENTS IN SIGNALLING APPARATUS IN CONNECTION WITH
VACUUM BRAKES FOR RAILWAYS
The objects of this invention are to make known to the engine-driver or guard
of a train to which pneumatic brake apparatus is fitted when leakage has occurred
in the vacuum pipes, and has put the apparatus out of order, and also to enable
passengers to signal to the attendants of a train.
In pneumatic brake apparatus it is usual to connect the vacuum pipes with a
small air ejector which is in constant action. This will produce a low vacuum in
the pipes too feeble to put the brakes in action, but it greatly facilitates the
exhaustion of the pipes by a large ejector which is put in action by the engine
driver when the train is required to be retarded or stopped.
To afford an indication that the pipe joints are sound, a visible signal is now
used on some lines of railway.
I propose however to add to this signalling apparatus an audible signal. Thus,
I apply for example to the Gresham form of indicator which consists of an
oscillating double faced angle plate working behind a longitudinal opening in the
face of a pressure gauge a bell and hammer for calling the attention of the driver
or guard to the visible indicating apparatus.
The oscillating angle plate carries a cam pieco which is intended to act upon the
tail of the bell hammer when the signal is to be given. The oscillating angle
plate is linked to a flexible diaphragm or floating piston fitted to the case of the
indicator such diaphragm or piston being open at one side to the vacuum pipe of
the train.
On the axle of the oscillating angle plate a spring is coiled which spring serves to
bold the visible signal to "wrong" when the vacuum in the pipe is defective.
When however the vacuum holds back the diaphragm or piston the visible
signal will shew" " right."

page_text: It is to give an audible indication of a defect in the vacuum pipe, at the same
time that the visible signal is given that the bell and a spring hammer are
introduced.
The tail of the hammer is jointed to allow the cam piece of the oscillating plate
to pass freely under it to the back, and at this position it stands, so long as the
vacuum is properly maintained. When, however, air is admitted to the vacuum
pipe, the coiled spring being no longer restrained will bring the signal "wrong" into
view, and at the same time the cam piece striking the tail of the hammer will rock
the hammer, put a tension on the spring with which the hammer is provided, and
passing under the tail of the hammer will allow the same to return under the pull
of its spring and strike the bell.
The same effect will be produced if a passenger by opening a valve in connection
with the vacuum pipe admits air thereto and by establishing a code, a repetition of
such signals may be made to communicate any required information to the guard
or engine driver.
My invention is also applicable to automatic vacuum brakes, and independently
of the visible signal.
In this case also the diaphragm or piston in communication with the vacuum
pipe may, through its connection with a rock lever or shaft be caused to act on the
hammer as before, and thereby give the audible signal.
The enclosing chamber may be exhausted on both sides of the piston or
diaphragm, an opening covered by a clack valve which opens towards the exhaust,
being provided in the diaphragm or piston to permit of the simultaneous
exhaustion on both sides of the diaphragm or piston. Or a spring may be used on
one side to counterbalance the action of the vacuum on the other side of the
diaphragm or piston, and serve, like a rush of air in the first example, to set the
apparatus in action.