IMPROVE. MENTS IN TRAMWAYS
Year: 1873

page_text: PROVISIONAL SPECIFICATION left by Hiram Codd at the Office of
-
the Commissioners of Patents, with his Petition, on the 18th
January 1873.
I, HIRAM CODD, of Grove Lane, Camberwell, in the County of
Surrey, do hereby declare the nature of the said Invention for "IMPROVE.
MENTS IN TRAMWAYS," to be as follows:-
This Invention has for its object to construct tramways which are
laid along streets or roads in such a manner that they shall not interfere
with the ordinary traffic, and that the surface of the tramway shall
always be level with the road surface without any grooves in it of a
sufficient width for the wheels of ordinary vehicles to enter: For this
purpose in place of the guiding or supporting wheels of the tram cars
being arranged to run in open grooves in fixed rails as usual I arrange
that the wheels shall run in grooves or channels which open as the
wheels come up, and again close after the guiding or supporting wheels
of the car have passed so as to leave an even surface over which the
ordinary wheeled vehicles can run freely. This may be effected by
forming the groove or channel in which the wheels are to run of two
"

page_text: sets of parallel plates laid side by side and supported at their adjacent
sides upon pin joints, so that when a wheel having a V shaped periphery
presses upon the adjacent edges of such plates, the plates turn upwards
upon their pin joints and form a V groove for the wheels to run in.
The plates are carried by trough shaped supports which are fixed down
to the sleepers, the pins or joints upon which the plates turn are carried
by partitions formed across such trough shaped supports, and the outer
edges of the plates rest upon and are supported by the sides of the
trough. One set only of parallel plates might also be used if the guide
wheels of the car be made conical at their periphery. In this case the
edge of the plates comes up to and is level with the top of the trough.
When the wheel presses upon the edge of the plates it turns them on
their pin joints and runs in the groove so formed between them and the
side of the trough. The wheels of the tram cars when they turn the
plates upwards as above described may rest upon a fixed narrow rail of
steel, so that the weight of the car is not supported by the movable
plates, but these only serve as guides to compel the car to travel in a
straight course along the tram.
The supporting wheels of the tram cars might also be arranged to run
upon broad flat surfaces whilst other guide wheels carried at the central :
line of the cars might act with a single central guide rail or channel
constructed as above described; in place also of using jointed plates along
one or both sides of a rail as above described, the tram wheels might run
upon a fixed rail made hemispherical on its under side and supported at
intervals by pins or studs from the bottom of a curved trough which
is concentric with the under side of the rail, and in the space between
the trough and rail semi-cylindrical curved plates are introduced.
When the tram cars are not moving over the rails the upper edges of
these filling plates are level with the top of the trough and of the rail,
so as to make a level surface over which ordinary wheeled vehicles can
pass freely; but when the tram car moves along the rails flanges upon
the wheels of the car act upon one edge of the filling plates and depress it,
so opening a groove between the rail and trough in which the flanges of
the wheel remain; and at the back of the car a roller is arranged to act
upon the opposite edges of the filling plates and to move the plates
back again to their original position so as to leave their upper edges
level with the surface of the rail. The filling up of the groove by stones
or dirt entering into it is thus prevented.

page_text: In order also that a groove may not be worn in the road along side of
the sleepers which carry the tram rails, I form the outer edges of such
sleepers with projections at intervals so that in place of the wheels of an
ordinary carriage running in a rut along side of the sleepers, the wheel
is continually lifted out of any rut or hollow that may be formed by the
projections from the sides of the sleepers, and thus the rut is not liable
to be worn continually deeper and deeper.