An Improved Worm Wheel.
Year: 1892

page_text: Date of Application, 5th Oct., 1892
Complete Specification Left, 5th Aug., 1893-Accepted. 9th Sept., 1893
PROVISIONAL SPECIFICATION.
An Improved Worm Wheel.
I, PETER WALLACE of 40 Prince Street, Pollokshields, Glasgow, Scotland,
Master Mariner, do hereby declare the nature of this invention to be as follows:-
This invention relates to a worm-wheel the periphery of which is furnished with
teeth so as to engage with the thread of a worm, and consists in cutting the teeth
so as to engage either simultaneously or separately with worms having a right-hand
or left-hand thread. To effect this I cause the periphery to be cross cut so that
the teeth are intersected with diagonal lines, and there remain only triangular lugs
with interstices for the thread of the worm. If this is properly done the wheel will
engage on one side with a right hand thread and on the opposite side with a left
hand thread, thus enabling two shafts to operate the wheel or to be operated by it,
a result of considerable importance in some mechanical movements.
Dated this 5th day of October 1892
S. S. BROMHEAD,
97, Newgate Street, E.C., Agent for Applicant.
COMPLETE SPECIFICATION.
An Improved Worm Wheel.
I, Peter WALLACE of 40 Prince Street, Pollokshields, Glasgow, Scotland,
Master Mariner, do hereby declare the nature of this invention and in what manner
the same is to be performed, to be particularly described and ascertained in and by
the following statement :-
This invention relates to worm or screw gearing, and refers more especially to
spur wheels or toothed wheels which engage with the thread of a screw or worm on
a shaft or axle. It consists in so forming the teeth on the periphery of the wheel
that the wheel will engage either separately or simultaneously with screws or
worms having a right hand or left hand thread.
To effect this I cause the periphery of the wheel to be cross-cut so that the teeth
are intersected by diagonal channels or lines. If this be properly done there will
remain on the face of the wheel, triangular or diamond shaped lugs, shewing an
inclined surface in either direction. Between these projections will be interstices
for the thread of the worm. The wheel will now engage on one side with a right
hand screw and on the opposite side with a left hand screw, so that it can engage
with two shafts at the same time, and consequently can operate two shafts or can
transmit motion from two shafts, or can receive motion on one side and transmit it
reversed on the other. These advantages are of considerable importance in some
mechanical movements, as for instance in steering gear for large ships, and in wind-
lasses, turning gear, and for driving of any description where a common worm
wheel is used, as the power can be applied more uniformly, and the liability to
break down is lessened.
I will now describe the invention with reference to the accompanying drawings
in which
Fig. 1, shows a plan view of a worm wheel arranged for steering gear, and driven
simultaneously by two shafts, one of which has a right-hand screw and the other
a left hand screw.
Fig. 2, shows a sectional elevation of a capstan with the worm wheel on top, as
used for steering purposes, and displays the special form of projecting lugs or
teeth.

page_text: a is the worm wheel.
bb are the double action teeth.
c, c, are worms on shafts, one being right-hand and the other left hand.
d is the axle of the worm wheel.
e, e, are the shaft bearings.
is a chain wheel for conveying power to quadrant of rudder post.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed I declare that what I
claim is :-
An improved worn-wheel the periphery of which is formed with double action
teeth so as to cugage with either a right hand or left hand screw simultaneously or
separately, as herein described and set forth.
Dated this 5th day of August. 1893
S. S. BROMHEAD,
97, Newgate Street, London, E.C., Patent Agent.