IMPROVEMENTS IN THE DRIVING WHEELS OF LOCOMOTIVE ENGINES, AND IN THE PERMANENT WAY
Year: 1877

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, for the Invention of "IMPROVEMENTS
IN THE DRIVING WHEELS OF LOCOMOTIVE ENGINES, AND IN THE PERMANENT
WAY." A communication from abroad by Jean Larmanjat, of Paris, France.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark
at the Office of the Commissioners of Patents on the 7th March 1877.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent. "IMPROVEMENTS IN THE DRIVING WHEELS OF LOCOMOTIVE ENGINES,
AND IN THE PERMANENT WAY." A communication from abroad by Jean Larmanjat,
of Paris, France.
This Invention consists mainly in providing the driving wheels of locomotives
with movable spring teeth to gear with racks alongside the rails to facilitate the
ascent of steep gradients.
The Invention is illustrated by way of example in the accompanying Drawing.
Figure 1 shows a face view with the cover plate removed.
And Figure 2, a transverse section of a railway wheel, showing the way the teeth
are fitted, and the internal construction of the wheel.
Figure 3 represents the cover plate separately, and shows the circle of lugs on said
plate to limit the movement of the spring teeth A.
Figure 4 shows a cross section, and Figure 5 a side elevation of the ordinary and
rack rails fixed on a longitudinal sleeper.
Figure 6 represents a plan of the sleeper, with an improved metallic tie bar H
bent at right angles at h, h, inside and outside the sleeper to maintain the guage of
the line.
Each spring tooth A has attached to it a small spring catch B, which engages
with the circle of lugs in plate F to retain the teeth A withdrawn into the wheel, as
represented in the case of the tooth A¹. The teeth A are fitted to slide in and out
in sockets in the wheel, and have spiral springs C on their inner ends, by which they
are projected beyond the periphery of the wheel when the catches B are released from

page_text: the lugs on plate F, which is effected in the following manner :-D, D, Figure 1, are
two blocks fixed on the inner face of the plate F, and received in circular grooves in
the body of the wheel containing springs E. By turning plate F round on the
wheel a distance equal to the width of a lug the spring catches B will be no longer
retained by the lugs, and the teeth A will be projected outwards to the full extent
by their springs C. The plate F, which may be revolved by any suitable means,
such as by a brake for example, is returned to its original position by the springs E,
so as to bring the lugs in plate F in line with the spring catches B to retain
the teeth withdrawn into the wheel whenever they are driven inwards by any
obstacle, as shown by the tooth A", Figure 1, which having passed the toothed part
of the rack rail F is driven inwards on arriving at the plain part of the rail. This
plain part is equal in length to the circumference of the wheel, so that the whole of
the teeth will be similarly driven inwards, and thus form no obstacle to ordinary
travelling when they are not required.
This construction of wheel is more particularly applicable on lines with gradients
exceeding 1 or 2 in 100, and the advantage of such an arrangement of toothed
gear coming into operation only at places where the driving wheels of the locomotive
would slip would be readily seen.
The great objection to the employment of toothed gearing on railways has been
due to the difference in the circumference of the toothed and plain portions of the
wheels, for if at any moment sufficient adhesion is obtained on the smooth rail the
teeth of the wheel are caused to ride upon the teeth of the rack instead of falling
in the spaces between them, and they become not only useless but dangerous. This
objection is entirely obviated in the wheel of this Invention, the spring teeth
gearing instantly with the rack wherever it is provided on the rails. To appreciate
the gain in power realized it is only necessary to mention that under ordinary
circumstances the tractive power of an engine is no more than one-seventh of its
weight, but by means of this Invention the power is increased to upwards of one-
half its weight.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alexander Melville Clark in the Great Seal Patent Office on the 1st
September 1877
.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent. "IMPROVEMENTS IN THE DRIVING WHEELS OF LOCOMOTIVE ENGINES,
AND IN THE PERMANENT WAY." A communication from abroad by Jean Larmanjat,
of Paris, France.
This Invention relates to an improvement upon that form of traction or driving
wheel for locomotives, in which spring seated teeth are arranged to project radially
from the wheel, which teeth secure a better hold, and at the same time yield to any
obstruction that may present itself.
;
The improvement consists in the means for controlling the said teeth, as herein-
after described, whereby they may be allowed to project to engage with a rack rail
to increase the traction or be withdrawn into the periphery of the wheel, as may be
desired.
The Invention is illustrated in the accompanying Drawings, in which,-
Figure 1 shows a face view of a railway wheel with the cover plate removed.
Figure 2, a transverse section, showing the way the teeth are fitted, and the
internal construction of the wheel.
Figure 3 represents the cover plate separately, and shows the circle of lugs on
said plate, whereby the spring teeth are retained, as herein-after described.
Figure 4 shows a cross section; and Figure 5, a side elevation of the ordinary
rail, with the rack rail alongside of it, and both fixed on a longitudinal sleeper.

page_text: Figure 6 represents a plan of the sleeper with an improved metallic tic: bar H,
bent at right angles at h, h, inside and outside the sleeper, to maintain the gauge of
the line.
Each spring tooth A has attached to it a small spring catch B, which engages
with the circle of lugs. I in a circular groove K in plate F, which lugs serve to
retain the teeth A withdrawn within the wheel, as represented in the case of the
tooth A. The teeth A are fitted to slide in and out in sockets L in the body of
the wheel, and have spiral springs C on their inner ends, by which they are pro-
jected a certain distance (limited by the shoulders a on the teeth) beyond the
periphery of the wheel, when the catches B are released from the lugs on plate F,
which is effected while the engine is travelling in the following manner :-D, D,
Figure 1, are two blocks fixed on the inner face of the plate F, and received in
circular grooves M in the body of the wheel containing springs E. By turning
plate F round on the wheel a distance equal to the width of a lug I the spring
catches B will be no longer held by the lugs I, but will pass between them, and the
teeth A. will be projected outward by their springs C. As the wheel is rotating
when the gear teeth A are brought into action it is sufficient to retard the plate F
by any suitable means, by a brake for example, in order to release catches B from
lugs I, and cause the teeth to project. If the brake be now released the plate F
will be returned to its original position by the springs E, so as to bring the lugs in
plate F again in line with the spring catches B. Should any of the teeth now be
driven inward by encountering any obstacle on the rack rail its catch B will slip
over the lug I, and the tooth will remain withdrawn into the wheel, as shown by
the tooth A, Figure 1, which having passed beyond the toothed part of the rack
rail Fis driven inward on arriving at a plain length of rail provided at the end of
the rack rail. This plain part is at least equal in length to the circumference of the
wheel, so that the whole of the teeth of the wheel will be similarly driven inward
immediately they are no longer required, and thus form no obstacle to ordinary
travelling. The plate F is fitted to rotate on the boss of the wheel, to which it is
connected by bolts N passing through sufficiently elongated slots O to admit of the
rotary movement of the plate F on the wheel.
This construction of wheel is more particularly applicable on lines with gradients
exceeding one or two in one hundred, and the advantage of such an arrangement of
teeth coming into operation only at places where the driving wheels of the locomo-
tive would slip will be readily scen.
The great objection to the employment of toothed gearing on railways has been
due to the difference in the circumference of the toothed and plain portions of the
wheels, for if at any moment sufficient adhesion is obtained on the smooth rail the
teeth of the wheel are caused to ride upon the teeth of the rack instead of falling
in the spaces between them, and they become not only useless but dangerous. This
objection is entirely obviated in the wheel of this Invention, the spring teeth gearing
instantly with the rack wherever it is provided on the rails. To appreciate the gain
in power realized it is only necessary to mention that under ordinary circumstances
the tractive power of an engine is no more than one-seventh of its weight, but by
means of this Invention the power is increased to upwards of one-half its weight.
Having described the nature of the said Invention, and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
berein-before in part recited Letters Patent is,-
1st. A locomotive driving wheel provided with radially arranged spring seated
teeth combined with catches for holding them withdrawn into the wheel, substan-
tially as and for the purpose described.
2nd. The driving wheel having the radially arranged spring seated teeth provided
with spring catches B in combination with the concentric plate F made adjustable
upon its centre, and having lugs I adapted to hold the said teeth in when in one
position, or to be turned to allow the same to project, substantially as described.
3rd. The circularly arranged spring E and movable block D in combination with

page_text: the driving wheel having radially arranged spring seated teeth having spring catches,
and with adjustable plate F having lugs I, substantially as described and for the
purpose set forth.
In witness whereof, I, the said Alexander Melville Clark, have hereunto set
my hand and seal, this Thirty-first day of August, in the year of our Lord t
One thousand eight hundred and seventy-seven.