IMPROVEMENTS IN SPEED INDICATORS FOR VELOCIPEDES, AND IN THE MODE OF COMBINING THE SAME WITH THE BREAK LEVER, AND ALSO IN THE METHOD OF ATTACHING THE BREAK TO THE VEHICLE
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by Henry Selby Hele Shaw and
Edward Shaw at the Office of the Commissioners of Patents on the 14th July
1881.
"
HENRY SELBY HELE SILAW, Assoc. M. Inst. C.E., Lecturer, University College,
in the City & County of Bristol, and EDWARD SHAW, Pembroke Vale, Clifton,
Bristol. IMPROVEMENTS IN SPEED INDICATORS FOR VELOCIPEDES, AND IN THE
MODE OF COMBINING THE SAME WITH THE BREAK LEVER, AND ALSO IN THE
METHOD OF ATTACHING THE BREAK TO THE VEHICLE."
This Invention relates to the construction of an improved speed indicator for
velocipedes which may be attached to the break lever, so that a similar movement
to that now used may be made to bring into action either the break or the speed
indicator. The mechanism of the speed indicator is caused to act by the revolution
of a hollow roller, a narrow ring tixed on the outside of which is brought into
contact with the periphery of a wheel on which the vehicle runs.
The break consists of an L shaped metallic lever, the top of the upright arm
being connected by a link to the break handle. At one part of this lever is a slot
into which enters a fixed pin upon which the lever turns. A certain amount of
up and down play is allowed in the slot for the purpose hereinafter described.
The extremity of the horizontal arm forms the break which can be caused to bear
upon the periphery of the wheel of the vehicle, and thereby slacken the speed. A
part of the horizontal arm is made circular and hollow in the centre, thus forming
a kind of frame to which is attached the cylindrical casing of the speed indicator.
In the circular and hollow part of the horizontal arm of the break lever are fitted
two hardened steel bearings for the purpose of carrying the spindle of the hollow
roller above mentioned. Upon this spindle works a governor, somewhat similar to
the ordinary ball governor of a steam engine. Upon one end of the spindle
outside the hollow roller, slides a cap or collar having a groove in it, and which for
convenience we will call the top cap or collar. Inside the said hollow roller upon
the spindle also slides a botton cap or collar, which is connected to the top cap or
collar by means of two guide rods which pass through the top plate of the hollow
roller. Connected to the bottom cap or collar are the top arms of the governor.

page_text: The two bottom arms are connected to the bottom plate of the hollow roller, and
these top and bottom arms in their normal position lie nearly parallel with the
spindle. At the junction of the top and bottom arms are arranged ordinary
governor balls.
The two top arms are made shorter than the two bottom arms,
so that the readings at high speeds are more uniform than they otherwise
would be.
Inside the cylindrical casing of the speed indicator is arranged a rod, one end of
which is forked and takes into the groove of the above mentioned top cap or
collar, the other end being fixed to a rack and capable of sliding backwards and
forwards in a groove cut in a plate fixed in the casing. This rack gears with a
small pinion, upon the spindle of which is fixed a needle which indicates upon a
suitably marked dial the rate of speed at which the vehicle is travelling. The top
of the speed indicator is covered by a glass cover, and the bottom is covered by a
metallic plate having a slot in the centre through which the narrow ring on the
hollow roller projects. A steel scraper is fixed on the bottom plate against the
projecting part of the hollow roller so that it is constantly scraped clean.
Attached to the upright arm of the lever is a spring, the other end of which is
connected to the frame of the vehicle, and which keeps the break and the speed
indicator in their normal position off the wheel. By moving the break handle a
certain distance the projecting part of the hollow roller of the speed indicator is
caused to bear upon the periphery of the wheel, thereby causing it to revolve at a
surface velocity equal to that at which the vehicle is travelling. The centrifugal
force will cause the weights on the arms of the governor to fly outwards, according
to the velocity, and will thus draw downwards the top and bottom caps or collars
against the resistance of a spiral spring coiled round the main spindle. In conse-
quence of the forked rod taking into the groove in the top cap or collar, the said
rod will be caused to slide forwards in the groove of the plate fixed inside the
casing, and the rack will cause the pinion to revolve, and the needle will thereby
indicate upon the dial the rate of speed of the vehicle. Upon releasing the break
handle the instrument will return to its normal position; and the hollow roller
ceasing to revolve, the spiral spring inside will cause the internal mechanism, and
with it the indicating hand or needle, to resume their original places.
By moving the break handle a greater distance than necessary for causing the
speed indicator to act, the upright arm of the break lever will be caused to slide
upwards on the fixed pin, on account of the play in the slot, and will thereby cause
the break to act upon the wheel and lessen the speed of the vehicle.
It will be easily understood that the speed indicator may be used separately
from the break, in which case the spindle of the hollow roller will revolve in
bearings fixed in the cylindrical casing of the instrument.