Improvements in Compensating Balance Lever Plates for Railway Signalling Purposes.
Year: 1895

page_text: Date of Application, 9th Aug.. 1895
Complete Specification Left, 9th May, 1896-Accepted, 13th June, 1896
PROVISIONAL SPECIFICATION.
Improvements in Compensating Balance Lever Plates for Railway
Signalling Purposes.
I, ARTHUR GEORGE EVANS, of 116 Palace Chambers, Bridge Street,
Westminster, in the County of Middlesex, Civil Engineer, do hereby declare the
nature of this invention to be as follows:-
My invention has reference to improvements in compensating balance lever
plates fixed upon signal posts in connection with operating the signal arm.
My invention can either be fixed acting as the ordinary balance lever plate of
the signal, or it might be fixed level with the arm so that the balance plate is
really part of the arm, thus displacing the ordinary balance lever plate upon the
signal post.
It is well known that, in consequence of the variations in temperature, if the
wire expands between the operating lever in the signal cabin and the balance lever
plate on the post, that the signalman in operating the said signal lever in his cabin
may do little more than take up the expansion of the wire and in many cases the
signal is not properly deflected, giving a doubtful signal. On the other hand,
should the weather be cold and the wire contract the balance lever on the post
might be moved to slightly deflect the signal when the signalman has not operated
his lever at all.
My invention has for its object that the arm remains in its true horizontal
position no matter what the variation in temperature may be and that any such
variation is allowed for in my improved balance lever plate.
The way in which I carry out my invention is as follows:
I will describe that form of my invention which takes the place of and displaces
the present balance lever plate on the post. My invention consists of a frame
preferably having two sides with a space in the middle in which a pulley wheel is
fixed, the fulcrum holding the plates together and forming the centre upon which
the pulley revolves and the plates themselves are tilted. The plates at one end
are connected to the ordinary upright rod for the deflection of the signal. A small
pulley wheel of suitable width for moving along the top of the plates is connected
by chain on the one side to the operating lever in the signal cabin and on the
other side to a loose balance weight.
The action of my invention is as follows:-
The normal position of the pulley to which the balance weight is attached
should be sufficiently to one side of the fulcrum to allow that the greatest amount
of contraction shall not tend to move this pulley to the other side of the plates
so that the plates might be tilted without the action of the operating lever. No
matter what the variation in temperature may be, that is to say, assuming it causes
expansion, the counter-balance weight attached to my apparatus on the post will
be lowered and will pull the pulley further along the plates thereby tending to
lock the signal arm at "danger." If now the signalman operates the signal lever
the pulley is moved along the top of the plates until it is beyond the fulcrum of
the plates, through which action the plates are tilted and the arm is deflected.
If contraction has taken place in the wire the pulley will be moved nearer to
the fulcrum and on the signalman operating his lever there will be less movement
necessary to deflect the arm, that is to say, the pulley will arrive beyond the
fulcrum of the plates, tilt the plates and deflect the signal ar
arm more rapidly..

page_text: A modification of my invention would be, in lieu of having only one pulley
between the two plates forming my improved balance plate, to arrange the chain
to pass over two pulley wheels acting substantially in a similar manner to that
herein before described.
Dated this 9th day of August 1895
JOHN P. O'DONNELL, Fel. Chart. Inst. P.A.,
70 & 71 Palace Chambers, Westminster, S. W.,
Agent for the said Applicant.
1
Improvements in Compensating Balance Lever Plates for Railway
Signalling Purposes.
I, ARTHUR GEORGE EVANS, of 116 Palace Chambers, Bridge Street,
Westminster, in the County of Middlesex, Civil Engineer, do hereby declare the
nature of this invention and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement :-
My invention has reference to improvements in compensating balance lever
plates fixed upon signal posts in connection with operating the signal arm.
My invention can either be fixed acting as the ordinary balance lever plate of
the signal, or it might be fixed level with the arm, thus displacing the ordinary
balance lever plate upon the signal post.
It is well known that, in consequence of the variations in temperature, if the wire
expands between the operating lever in the signal cabin and the balance lever
plate on the post, that the signalman in operating the said signal lever in his cabin
may do little more than take up the expansion of the wire and in many cases the
signal is not properly deflected, giving a doubtful signal. On the other hand,
should the weather be cold and the wire contract the balance lever on the post
might be moved to slightly deflect the signal when the signalman has not operated
his lever at all.
My invention has for its object that the arm remains in its true horizontal
position no matter what the variation in temperature may be and that any such
variation is allowed for in my improved balance lever plate.
In order that my invention may be better understood and more readily carried
into effect I will describe the drawings hereunto annexed.
Figure 1 is a front elevation of a signal post and arm showing the position in
which my improved compensating balance lever plate is fixed on the post. It
will be observed that this is the form which takes the place of the ordinary balance
lever and plate.
Figure 2 is an enlarged front view of that form of lever plate shown .in
Figure 1.
Figure 3 is a side view of Figure 2.
Figure 4 is a front view showing the application of my invention in the shape of
an arm plate, that is to say, fixed level with the arm, displacing the ordinary
balance lever and plate.
Figure 5 is a side view of Figure 4.
The same letters refer to the same parts in the several figures.
a is the compensating balance lever plate shown in Figures 1, 2 and 3 as in two
halves bolted together at the ends a¹ a', and fulcrumed to the base plate b at b¹;
intermediate between the two plates are pulleys c and d. To a projection e on the
end of the plates a the upright rod operating the signal arm is connected. The
usual chain f is connected at the end to the operating lever in the signal cabin
and at the end f' to a counter-balance weight f. In the chain are friction
{

page_text: rollers g, g¹ revolving on the plates a according as the signal lever operating the-
chain is moved or not.
In Figures 4 and 5 the invention is substantially the same, but in lieu of the
pulleys c and d one pulley h is substituted, revolving on the arm spindle j.
The action of my invention is as follows:-
Should the wire expand the counter-balance weight f³ falls by gravity and takes.
up
the slackness of the wire, the friction rollers g, g' moving along the top of the
plates a in the direction of the upright rod. Should the wire contract the weights f
move up and the friction rollers 9, 9 move in the opposite direction to that
previously described, towards the left." When the signal is required to be deflected
the signal lever in the cabin upon being operated gives a pull to the chain f.
moves the friction rollers g, g' along the top of the plates a and when they get beyond
the centre b¹ the continuation of the pull of the signal lever tilts the plates a,.
thereby moving upward the upright rod / and deflecting the signal arm.
Having now particularly described and ascertained the nature of my said inven--
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. A compensating arm-plate for railway signals consisting of a loose pulley, a
tilting plate, and a friction roller, substantially as described and illustrated in the
accompanying drawings.
2: A compensating balance lever-plate for railway signals consisting of two
pulleys, a tilting plate and a friction roller or rollers, substantially as described.
and illustrated in the accompanying drawings.
Dated this 9th day of May 1896
'
JOHN P. O'DONNELL, Fel. Chart. Inst. P.A.,
70 & 71 Palace Chambers, Westminster, S.W.,
Agent for the said Applicant.