Improvements in Automatic Expansion Gear for Steam Engines.
Year: 1892

page_text: Date of Application, 20th May, 1892
Complete Specification Left, 20th Feb., 1893-Accepted, 15th Apr., 1893
PROVISIONAL SPECIFICATION.
Improvements in Automatic Expansion Gear for Steam Engines.
I, JOHN SMITH RAWORTH of 112 Belvedere Road, Lambeth, in the County of
Surrey, Engineer, do hereby declare the nature of this invention to be as
follows:-
My invention relates to that class of automatic expansion gear commonly known
as flywheel governors in which centrifugal weights, counteracted by springs, vary
the position of an eccentric acting upon the steam valve in such a manner that the
stroke of the valve is altered according to the load on the engine while the lead or
point of admission of the steam is not much affected.
My invention has for its object the controlling of such automatic expansion gear
while in motion, within certain limits, so that it may be possible to vary the speed
of the engine by hand when desired, whatever may be the purpose for which the
engine is used, but more particularly when used for driving a dynamo electric
machine for the purpose of electric lighting or electric transmission of power.
According to my invention I tighten or relax one or both of the springs which
oppose the centrifugal force of the weights of the governor, or one or more
supplementary springs specially applied for the purpose. An arrangement of
meebanism for this purpose comprises an eccentric or its equivalent carried by the
crank-shaft and controlled by a spur wheel in connection with it, the said spur
wheel and eccentric being made a loose fit on the crankshaft. Adjacent to the said
spur wheel but firmly attached to the crankshaft I place a second spur wheel of
the same size as the first and having an equal number of teeth. On a fulcrum
near the crankshaft is fixed a swivel frame or bracket carrying two pairs of spur
wheels, each pair being the counterpart of the other pair, and arranged to run loose
on a pin fixed in the said swivel frame or bracket.
The wheels of each pair are joined together so that when one revolves the other
must revolve, but one wheel has one tooth more than the other, and they are
arranged in opposite positions, so that in the case of one pair the wheel having the
smaller number of teeth is nearer the engine, and in the case of the other pair the
wheel having the larger number of teeth is nearer the engine. The effect of this
arrangement is that when the swivel fiame is moved by hand, one or other of the
pairs of wheels can be brought into gear with the wheels on the crankshaft,
whereby the eccentric which influences the tension on the spring or springs will be
caused to advance or recede slowly, thereby varying the speed of the engine.
Dated this 20th day of Mov 1892
W. LLOYD WISE,
Per F. J. Brougham,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Automatic Expansion Gear for Steam Engines.
I, JOHN SMITH RAWORTH of 112 Belvedere Road, Lambeth, in the County of
Surrey, Engineer, 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 :-
My invention relates to that class of automatic expansion gear commonly known
as flywheel governors in which centrifugal weights, counteracted by springs, vary
the position of an eccentric acting upon the steam valve in such a manner that the
stroke of the valve is altered according to the load on the engine while the lead or
point of admission of the steam is not much affected.

page_text: My invention has for its object the controlling of such automatic expansion gear
while in motion, within certain limits, so that it may be possible to vary the speed
of the engine by hand when desired, whatever may be the purpose for which the
engine is used, but more particularly when used for driving a dynamo electric
machine for the purpose of electric lighting or electric transmission of power.
According to my invention I tighten or relax one or both of the springs which
oppose the centrifugal force of the weights of the governor, or one or more
supplementary springs specially applied for the purpose.
In the accompanying drawings,
Fig. 1 is an end elevation;
Fig. 2 a plan; and
Fig. 3 a longitudinal section illustrating an arrangement of mechanism for this
purpose applied to an ordinary flywheel governor.
a is the wheel; b the crankshaft; and c c the governor balls the centrifugal
force of which is resisted by a spring not shown in the drawings. d is a supple-
mentary spring the tightness of which can be controlled by hand while the engine
is working. One end of this spring d is attached to the governor arm f and the
other end to an eccentric strap that is fitted to an eccentrick which is loose on
the crankshaft. is a spur wheel connected directly with the eccentric k and m is
a spur wheel keyed to the crank shaft. These two spur wheels and m are of the
same size and have an equal number of teeth.
g
o is a swivel frame or bracket mounted on a fulcrum or pin p fixed on stationary
support near the crankshaft b and carrying two pairs of spur wheels viz. r and 's
each pair being the counterpart of the other pair and arranged to run loose on a
pin t fixed in the said swivel frame or bracket.
The wheels of each pair are joined together so that when one revolves the other
must revolve, but one wheel has one tooth more than the other, and they are
arranged in opposite positions, so that in the case of one pair the wheel having the
smaller number of teeth is nearer the engine, and in the case of the other pair the
wheel having the larger number of teeth is nearer the engine. The effect of this
arrangement is that when the swivel frame is moved by a handle lever t connected
therewith; one or other of the pairs of wheels r and s can be brought into gear with
the wheels. m on the crankshaft, whereby the eccentric which influences the
tension on the spring d (or springs) will be caused to advance or recede slowly,
thereby tightening or slackening the spring and corresponding varying the speed
of the engine.
vis a link for the purpose of preventing the eccentric strap from
revolving with the eccentric.
Having now particularly described and ascertained the nature of the said iuven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. Controlling automatic expansion gear of the kind commonly known as fly-
wheel governors by tightening or relaxing by hand and while the engine to which
the expansion gear is applied is in motion, one or more springs that oppose the
centrifugal force of the weights of the governor substantially as described and
shown.
2. The combination with automatic expansion gear of the kind herein referred
to, of a supplementary spring d and mechanism for tightening or relaxing the said
spring said mechanism comprising spur wheels having an unequal number of teeth
and arranged to operate substantially as hereinbefore described.
W. LLOYD WISE,
Per F. J. Brougham,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.