IMPROVEMENTS IN TRAM CARS AND OTHER SIMILAR VEHICLES &
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by John Henry Johnson at the
Office of the .Commissioners of Patents on the 19th April 1883. Com-
municated to him from Messieurs Husard and Eude residing at Harfleur in
the Republic of France
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JOHN HENRY JOHNSON, of 47 Lincolns Inn Fields, in the County of Middlesex,
Gentleman, IMPROVEMENTS IN TRAM CARS AND OTHER SIMILAR VEHICLES &
communication to me from Messieurs Husard and Eude residing at Harfleur in
the Republic of France
This Invention consists in providing tramcars or other like Vehicles with means
hereinafter described whereby the propelling power is enabled to be applied under
more advantageous conditions than heretofore-It is well known that the force
required on first starting a vehicle is much greater than that necessary to propel
the same Vehicle after it has been set in motion
By means of the improved apparatus hereinafter described the starting of a
Vehicle is accomplished without a greater expenditure of power than that normally
required to keep it running
In starting a Vehicle of ordinary construction the power acts on the wheels at
the centre so that the length of the lever is only equal to the length of the radius
of the wheel-By increasing the length of this lever it is evident that the tractive
force applied to the wheel will be increased in proportion to the length of the lever
In carrying out this Invention the draw bar or its equivalent is so arranged as
to be capable of moving relatively to the frame of the Vehicle within certain limits
in the direction of its length being connected to the said frame by a spring and is
also jointed to an arm or arms acting as a pawl capable of engaging with the upper
part of a ratchet wheel or wheels rigidly connected to or preferably formed in one
piece with one or more of the travelling wheels of the Vehicle-This pawl bar is
also connected by a chain or its equivalent to the frame of the Vehicle and is
pressed towards the wheel by a spring
When the wheel is stationary or not more than the ordinary propelling power is
required the draw bar is drawn back by the traction spring into such a position
that the chain connected to the pawl bar is stretched and holds the said bar out of
contact with the wheel

page_text: When it is required to start the Vehicle or from any reason more than the
ordinary propelling power is demanded the traction spring is compressed by the
strain on the draw bar and the pawl bar being hinged to the draw bar moves with
the latter towards the relatively stationary point where the chain of the pawl bar
is attached to the frame-The result of this motion is that the chain is slackened
and allows the spring acting on the pawl bar to push the latter against the ratchet
wheel or wheels on the travelling wheel or wheels whereby this bar is caused to
transmit to the upper part of the said wheel the impulse that it receives from the
draw bar-The tractive force is thus caused to act chiefly upon the upper part of
the wheel that is to say with a length of lever equal to the diameter of the wheel
instead of being only equal to the radius as in the ordinary arrangement.
When the vehicle is set in motion and not more than the ordinary propelling
power is required the traction spring returns nearly to its original position and
draws the draw bar and pawl bar back with it; this latter being thus moved away
from the relatively stationary part of the frame to which it is attached by the
chain herein before referred to is thus pulled out of contact with the wheel and the
propulsion is continued in the ordinary manner.