IMPROVEMENTS IN WIRE TRAMWAYS
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by John Brown at the Office of the
Commissioners of Patents on the 16th February 1882,
JOHN BROWN, of 113 Cannon Street, in the City of London, "IMPROVEMENTS
IN WIRE TRAMWAYS,"
My improvements are especially directed to remedy a defect in wire-tramways
hitherto regarded as insurmountable. When the inclination of the path taken by
the wire exceeds a certain angle or gradient, a difficulty is experienced in pre-
venting the ordinary carrier to which the load is attached from slipping on the
wire; and when the inclination to be ascended becomes very considerable, it not
only arrests the usual onward course of the load, but, were the load, by special
temporary means, placed on the wire-tramway at some part of its steep course, it
would immediately slip backwards on the wire.
I propose, in the following manner, to obviate this defect in wire tramways, when
it is desired to carry them up steep acclivities. I form a carrier or saddle in such
wise that it shall sit on, or rather straddle, the travelling wire, though certain
portions only of its under surface are to come into direct contact with the said wire.
It is oblong in form, of convenient dimensions, and made of any suitable material.
For a certain distance along its under surface, beginning at each end, I cut triangular
grooves, or grooves in the form of a saddle. These grooves may be lined with
india rubber, leather, or any yielding and elastic material, in order, to some extent,
to assist in preventing any tendency on the part of the saddle to slide on the wire.
This lining, however, is not very essential. Let it be supposed that the two parts
of the saddle just described are resting upon the wire, the underneath central part
of the carrier being perfectly free. Through the centre of the carrier in a vertical
direction, I make a hole sufficiently large, not only to admit, but to allow move-
ment or play to, the prolonged arms of a pincer or pinchers placed underneath the
saddle for the purpose of clasping and pressing the wire. The internal shape of
the jaws of the pincer will be curved so as to suit the form of the wire. On the
central part of the top of the carrier, I place, in an horizontal and transverse
position, a small shaft. To one end of this shaft is suspended by means of a
curved and articulated rod, the load to be carried, which is made to occupy a
position strictly vertical in its relation to the wire.

page_text: I now come to the most important part of my Invention. From the upper part
of the aforesaid shaft, where it crosses the centre of the carrier, rises a stud, the
plan or horizontal section of which has an accutely elliptical form, or it may be
likened to the longitudinal section of a spindle. The two arms of the pincer
before-mentioned rise above the shaft, and reach at least to the level of the top of
the stud, The end of each is shaped fork-wise, so that the shaft may occupy freely
the passage thus made. Now it is evident that any opening or separation of these
arms must tend to close the jaws of the pincer, and thus force them to act
upon the wire. This occasionally necessary tightening is effected in the following
manner-Each sharp end or edge of the stud reaches the line which, on each side
of the shaft, separates the two arms. If the shaft turns, the stud must accompany
it, and in its course necessarily force open more or less widely the arms just men-
tioned; thus compelling the pincer to fasten its jaws upon the travelling wire.
This action is unnecessary whilst the course of the wire is over level or slightly
undulating ground, because the load underneath hanging vertically, and therefore
at right angles, or nearly so, to the wire, no slipping of the carrier on the wire is
to be apprehended. But in ascending any considerable acclivity, it would be
brought into play; for the curved and articulated rod before-mentioned, which is in
fact a prolongation of the shaft, ever maintaining its vertical position, owing to the
weight of the load attached to it, would form a more or less acute angle with the
wire in its ascending course. This persistent vertical position of the rod with its
burthen, would have the effect, under the changed circumstances, of turning the
shaft and with it the stud, which would then separate the arms of the pincer, and
force it to tighten its grasp on the wire; thus preventing any backward or sliding
movement of the saddle. This tightening action must obviously increase in
proportion to the increase of the acclivity to be ascended.
The object of my Invention is the effectual holding of the wire, at certain times,
by the jaws of a pincer, and I prefer to effect this in the manner described; but
there are various modifications by which I might produce this closing movement of
the jaws.