IMPROVE- MENTS IN AUTOMATIC FOG SIGNAL APPARATUS
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by Henry Whitehead and Thomas Dodd
at the Office of the Commissioners of Patents on the 10th May 1881.
HENRY WHITEHEAD,. of Bucknall, in the County of Stafford, Coal Merchant,
and THOMAS DODD, of Winsford, in the County of Chester, Engineer. " IMPROVE-
MENTS IN AUTOMATIC FOG SIGNAL APPARATUS."
The nature of this Invention appears in the title, and it is carried into effect in
the following manner :-We provide two cast iron brackets which are secured to the
outside of the rail at suitable distances apart, and which may be, say, about twenty
one feet. The first of these brackets is intended to carry one end of the depression'
bar, to which it is secured by an iron stud. The said depression bar is proposed to
be about twenty two feet in length, and is formed by preference of two and a half
inch T iron.
The other bracket is for the purpose of carrying a bearing for a cross shaft, which
may be about one and a half inches in diameter and four feet in length. Inside
the rail on the end of this cross shaft is keyed a lever, which is attached to the
other end of the depression bar. For the opposite end of this cross shaft a bearing
is provided and secured to the sleeper by two screw bolts. On the cross shaft
near to this bearing a bell crank or lever is keyed, on which is placed a balance
weight for the purpose of raising the depression bar after it has been lowered, and
withdrawing the connecting rods and slides to their normal positions after the
passing of a train. Two castings are also provided, one of which is fixed about
three feet from the cross shaft before named. The other casting is fixed about
eighteen feet from the first. One end of these castings is firmly secured to the
outside of the rail, and the opposite end is secured to the sleeper by screw bolts or
by other suitable means. These castings are provided with a recess from end to
end, the bottom of this recess being on a level with the face of the rail. Over this
recess the cover is secured by means of four screw bolts, this recess then forming a
channel along which the detonators or fog signals may be propelled to the face of
the rail. On the end of this cover farthest from the rail a socket and flange is
provided for the purpose of carrying the tube which is to contain the needful supply
of detonators or fog signals for the machines. This tube is placed in the socket
before named and is proposed to be secured to the flange by two screw bolts.
The tubes have two cases, one being placed inside the other, and there is a groove

page_text: about an inch in width nearly the entire length of the cases. A part movement of
the outside case places the two grooves exactly opposite to each other, and when in
- this position the tubes can be filled with detonators or fog signals, after which the
outside case can be turned to its normal position.
On one side of each of the two castings, at the end farthest from the rail, a bell
crank is provided, one end of which is attached to a slide which is caused to move
in the recess before named, these slides being for the purpose of propelling the
detonators or fog signals.
A casting is also provided and secured to a sleeper by means of two or more
screw bolts, about nine feet from each of the two machines.
This casting is for the purpose of carrying a T lever, on one end of which is
placed a balance weight. To the upper end of this T lever a wire is attached, which
is carried forward a distance of about thirty yards, and attached at the end to the
lever of the signal or semaphore arm.
At the bottom end of this lever two connecting rods are attached, one being
carried forward and attached to the bell crank on the first of the machines, which
we will call number one machine, the other being carried forward and attached to
bell crank on number two machine.
From the end of the connecting rod near the bell crank on number one machine
a chain is attached and carried forward and attached to the bell crank on the cross
shaft on which the balance weight is placed.
It will thus be understood that the first wheel of any carriage or train upon
passing this point will cause the depression bar to be lowered, this will in turn
cause a part revolution or motion of the cross shaft and elevate the balance weight
on the bell crank from its normal position, and this will cause the connecting chain
to be slackened, and thus the balance weight on the T lever will come into action
and act upon the connecting rods, which in their turn will act upon the bell cranks.
The two slides will then be moved forward and two detonators or fog signals will
be placed on the face of the rail, the tread or face of the wheel passing over them
will then cause two distinct explosions or reports at a distance of about six yards
apart; and immediately the train has passed clear of the machines the depression
bar will be raised, and all the other parts will resume their normal positions, and
the slides become recharged ready for the next train.
But in case the semaphore or signal arm should happen to be lowered before the
train reaches the machines (thus indicating a clear line) the wire connected with
the top of the T lever will prevent the machines from placing on the rail any
detonators or fog signals, and the train will then pass without any explosion taking
place. But immediately the semaphore or signal arm is again raised, the machines
would be ready for action as first, described.
It should be mentioned that we can use steel or other springs in the place of the
balance weights herein described if desired.