IMPROVEMENTS IN TRAMWAY CARRIAGES AND APPLIANCES USED IN CONNECTION THEREWITH
Year: 1879

page_text: PROVISIONAL SPECIFICATION left by John Smith Comrie at the Office
of the Commissioners of Patents on the 11th December 1879.
JOHN SMITH COMRIE, of 175, St. Vincent Street, in the City of Glasgow.
"IMPROVEMENTS IN TRAMWAY CARRIAGES AND APPLIANCES USED IN CONNECTION
THEREWITH."
This Invention has for its object improvements in tramway carriages, and
appliances used in connection therewith.
In order to facilitate the starting of tramway carriages, either when horses or
tractive engines are employed to draw them along a tram way, I use a draw bar
divided into two lengths meeting preferably at the centre of the car.
Here the
two lengths are coupled by an interposed spring or springs in such manner that
when draught is applied to the draught hook at the extremity of one draw bar it
compresses the spring or springs, and causes the other draw bar to be drawn
forwards, and this draw bar by a shoulder upon it then presses against the rear
end of the carriage, and pushes the carriage forwards.
Thus not only will the starting of the carriage be effected gradually instead of
with a blow or jerk, and so avoid injury to the horses shoulders or machinery of
the tractive engine, but also the carriage will be propelled by a pushing action upon
the rear end of the frame of the carriage, instead of as now usual by a distending or
pulling action, and by this means the wear and tear upon the fraine of the carriage
will be materially decreased.
For coupling together the two lengths of draw bar I prefer to use two ordinary
curved bow springs placed horizontally with their concave sides towards one
another and touching one another at their ends.
Each length of draw bar at its inner end I connect to the centre of the spring
furthest from the end of the carriage from which the length of draw bar passes.
The draw bars are for this purpose forked at their inner ends one with a single
fork, the other with a double fork. In place however of using bow springs a
coiled spring might be used, and be connected with the ends of the two lengths of
the draw bar, so as to effect the same objects.
In order that as the carriage is drawn along a tram way the tram rails may be
cleaned whenever they require to be cleaned, I mount at each end of the car a
frame which can be pressed downwards towards the rails by springs, or which can
be held up away from the rails when the cleaners are not required to be brought

page_text: into action. On each frame I mount two circular brushes one for each rail; these
brushes are carried on axes to which a revolving motion can be given from the
axle of the nearest pair of the running wheels of the carriage. The brushes and
their axles are inclined somewhat to the lines of rails, sc that the dirt removed by
them may be thrown to one side of the rail, but just at the point where the brush
acts upon the rail, and is required to enter and sweep the groove in the rail, I
deflect the bristles or parts of which the brush is formed by fixed guides placed on
either side of the brush, so that the parts of the brush immediately acting upon
the rail are caused to travel in a path parallel with the rail, but when they have
passed beyond these fixed guides they spring aside and throw any material removed
by them to one side of the rail.
Should it be desired a fixed vertical brush may be carried by the frame before
mentioned in front of each revolving brush to loosen mud caked on the rail, and
pulverize it before the revolving brush comes to it and sweeps it away to one side.
The frame may also carry a fixed prong or plough.
The revolving brushes I form by preference each of a disc, to which are jointed
all around its circumferences a number of tubes or holders each carrying a brush
composed of bristles or other material. Between the several tubes or holders are
cross pieces fixed to discs at the side of the disc to which the tubes or holders are
jointed. Each tube or holder carries, or is acted on by, a spring which bears
against one of the cross pieces, so that when the revolving brush is in action, and
any section of the brush encounters an obstacle on the rail the spring may yield to
some extent, and afterwards, as this section of the brush rises from the rail, the
spring may jerk away any material removed by the brush.