Improvements in Friction Brake Apparatus for Railways and Tramways.
Year: 1889

page_text: Date of Application, 17th Sept., 1889
Complete Specification Left, 17th June, 1890-Accepted, 19th July, 1890
PROVISIONAL SPECIFICATION.
[Communicated from abroad by E. DOHLEMANN, of Berlin, in the German Empire,
Engineer.]
Improvements in Friction Brake Apparatus for Railways and
Tramways.
I, CHARLES FAIRHOLME of No. 18 St. Dunstans Hill in the City of London,
Captain in the Royal Navy do hereby declare the nature of this invention to be as
follows:-
This invention relates to brake apparatus of that kind wherein when it is desired to
put on the brakes the rotation of a drum on a running axle is made by friction to
cause rotation of another drum brought in contact with it, so as to wind up a chain
connected to the brake levers, and thereby to bring the brake blocks to bear against
the wheels. In such apparatus, as it is usually arranged, the druin on the axle and
the drum which is brought in contact with it are in the same vertical plane and
consequently the oscillations of the carriage from which the second drum is suspended,
by varying the frictional contact of the two drums, causes variation of the strain with
which the brakes are pressed against the wheels. The object of the present invention
is to provide against this defect. For this purpose, two discs are mounted one on
each side of the axle drum their planes being at right angles to the plane of the drum,
the periphery of which faces the discs near their peripheries. The axle of each disc
is mounted in a swing frame and has connected to it one end of a chain which passes
over guide pullies and over a roller mounted on the one arm of a bell crank lever,
the other arm of which is connected by roils to the brake levers. Usually while the
vehicle is running the dises are held by means of a cord extending along the train
out of contact with the aslé drum and the chain is left slack, the brakes being' off.
But when it is desired to put on the brakes, or when the train cord is accidentally
broken, the dises are by means of a weight, no longer supported, made to press against
the axle drum and are thus caused to revolve by the frictional contact. By their
revolution they wind up the chain moving the bell crank lever and so causing the
brakes to be pressed against the wheels.
:
In order to prevent the brakes from being applied with excessive pressure such as
might cause the wheels to skid, the bell crank lever after moving a certain distance
raises a weight and thus relieves the strain with which one of the discs is pressed
against the axle drum the strain on the chain is thus relieved and consequently the
pressure of the brakes on the wheels. It is preferred to apply springs in the rods
leading to the brake levers so as to take off shock in applying the brakes. By
employing two discs as above described situated on opposite sides of the axle drum,
and both contributing to wind up the brake chain, the variations of strain on the
brakes due to oscillations of the carriage are almost entirely suppressed.
Dated this 17th day of September 1889.
ABEL & IMRAI,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Friction Brake Apparatus for Railways and
Tramways.
I, CHARLES FAIRHOLME of No. 18 St. Dunstans. Hill in the City of London, Captain
in the Royal Navy 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 :-
This Invention relates to brake apparatus of that kind, wherein when it is desired
to put on the brakes the rotation of a drum on a running axle is made by friction to
D

page_text: cause rotation of another drum brought in contact with it so as to wind up a chain
connected to the brake levers, and. thereby to bring the brake block's to bear against
the wheels. In such apparatus as it is usually arranged, the drum on the axle and
the drum which is brought in contact with it are in the same vertical plane and
consequently the oscillations of the carriage from which the second drum is suspended,
by varying the frictional contact of the two drums causes variation of the strain with
which the brakes are pressed against the wheels. The object of the present Invention
is to provide against this defect, as I will describe with reference to the accompanying
drawings in which Figure 1 shews a side elevation of the brake gear. Figure 2-a
plan. Figure 3 a part end view and Figure 4 a plan of the friction discs. Two
discs bare mounted one on each side of the axle drum a, their planes being at
right angles to the plane of the drum, the periphery of which faces the discs near
their peripheries. The axle of each disc is mounted in a swing frame m and has
connected to it one end of a chain which passes over guide pullies and over a roller e
mounted on the one arm of a bell crank lever pivotted at the other arm of which
is connected by rods to the brake levers. On bringing the discs in contact
with a they are rotated in contrary directions, and thereby simultaneously effect the
winding up of each end of the chain upon the rollers fixed on the axes of bb.
By this means the above described disturbing relative motion of the wheel axle and
the carriage frame is obviated as the said influence on the strain of the chain can no
longer take place, any yielding of the chain on the one rollor will at once result
in the winding on of a corresponding amount of chain on the other roller c.
The peculiarly formed frames m m are suspended at the points from the
framing A. and they are moved towards or from the axle drum a for bringing
the discs into or out of contact, by the action of their own weight controlled by
the slackening or tightening in the known manner of the continuous brake cords
acting upon the levers and pull rods o oo o² and o³ 0 0 0 0 0. For guiding the
chain, rollers ppare provided in fixed bearings in the frames, and the roller
levery works up and down in slots in the frame. On winding up the ends of the
chain on the rollers c c, the roller is drawn downward, thereby depressing the upper
arm of lever g, the lower arm of which acts on the brake rods yr. On the
axis of lever g is fixed a lever having a pin at its end which after the lever g
has been moved down a certain distance is made to bear against the upper end of a
slot in a lever k, and thereby to lift a weight Q, pivotted at to the one frame m¨so
as to convert this weight from a loading weight into a counterweight. The length
of the slot is somewhat smaller than the movement of the lever g g in order that,
as soon as the brake is applied, the weight shall no longer press against the axle
drum so as to cause a skidding of the wheels.
on
With favorable conditions of frictional contact the lifting of the weight is effected
at onco, while under unfavorable conditions it continues to act as a load, for increasing
the frictional contact until this is sufficient to apply the brakes. On releasing the
brakes, the weight acts as balance weight for raising the lever 99 and thereby
drawing the chain off the rollers e and removing the brake blocks from the
wheels.
The arrangement of the weight and of the double frictional surfaces will operate
beneficially upon the uniform action of the apparatus, even with unfavorable conditions
of frictional contact.
As the roller e can only move through a limited distance, which is not sufficient
to allow for a considerable wear of the brake blocks without adjustment, there is
provided in the brake gear a suitable self acting regulating device for the brake
blocks. For this purpose there are provided in the brake rods suitable springs.y
so that the application of the brakes is effected in an elastic manner.
The action remains the same both for the forward and the backward movement of
the carriage principally because any weakening of the action of the one half of
the apparatus is balanced by a corresponding increase in the action of the other half.
Fig. 5 shews a side elevation and Fig. 6 a plan of a modified construction of
the apparatus, in which the two friction discs are arranged on one and the

page_text: same side of the axle drum a, the object being to obtain a simplification and
cheapening of the apparatus, more particularly applicable for narrow gauge railways.
In this arrangement, as opposite sides of the discs are brought in contact
with the drum a they will be rotated in contrary directions as before, and will
consequently each effect the winding on of one end of the chain, the other end
of which is attached to the pivot of the frame m. The chains are led over
rollers e e suspended from levers w, the common axis of which rollers: is connected
by a link to the weighted brake lever . With this arrangement the one frame m
is, dispensed with, and the connections are simplified, and the extent of motion of
the roller is not limited, no spring adjustment of the brake blocks is required.
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 1
claim is:-
1. In friction brake apparatus for railways, the use of two friction dises bb that
are rotated in contrary directions by the axle drum a, and are thereby made to
wind up simultaneously either both ends of a single brake chain as at Figs. 1
to 4 of the drawings or the one end of two brake chains, as at Figs. 5 and 6.
2. In the construction of brake apparatus referred to in the preceding claim; the
use of a weight Q for loading the friction discs so as to compensate for unfavorable
conditions of friction, which weight, is automatically raised by levers i and k acted
upon by the brake chain, and afterwards acts as counterweight for taking off the
brakes.
Dated this 17th day of June 1890
ABEL & IMRAY,
Agents for the Applicant.