Improvements in Expansion Gear of Steam Engines.
Year: 1892

page_text: Date of Application, 9th June, 1892
Complete Specification Left, 8th Apr., 1893-Accepted 9th June, 1893
·PROVISIONAL specificatiON.
Improvements in Expansion Gear of Steam Engines.
1, GEORGE SELLERS M.I.M.E. of Wakefield, in the County of Yorkshire,
Consulting Engineer, do hereby declare the nature of this invention to be as
follows:-
:-
This invention relates to several "trip gear" devices to automatically vary the
period of cut off under the control of governors of ordinary or special construction
which latter can be adapted to Corliss, Cornish, piston, slide, or gridiron valves of
steam, air, or other engines.
The principal object of this invention is to provide an automatic expansion trip
gear and valve combined capable of being coupled to existing governors so that the
great cost of a new set of governors may be obviated.
According to this invention I key upon the valve spindle a disc or pulley having
a steel biting bit fitted at a point upon its periphery.
Mounted freely upon the said spindle is three-armed lever the longer arm of.
which receives a rocking or oscillating movement from some moving part of the
engine to which the device is fitted. The two shorter arms, which are above the
valve spindle, carry triangular steel triggers pivoted thereto, and the lower ends of
which are weighted and rest on the said disc or pulley, one on each side of the
biting bit.
It will be seen that by this arrangement, the oscillating movement
of the lever is communicated to the disc and valve spindle so long as the weighted
ends of the triggers rest upon the disc and against the sides of the biting bit.
The operation of the governors is made to raise the triggers from off the
disc by presenting an obstruction to the oscillation of their upwardly extending
The governors may act upon the triggers as described in several different
ways. According to one method two stop pins are carried by a toggle arrange-
ment which is operated by the governors so as to drive the said stop pins apart
and into contact with the upwardly extending arms of the triggers at different
points according to the speed of the engine. According to another arrangement
the governors actuate a right and left handed screw, through a sector and spur
gearing, which gives movement to the stop pins.
arms.
The valve is maintained in a normally closed position by means of a spring,
vacuum pot, or other suitable device, so that when the triggers are raised out of
position the valve assumes its closed position.
Dated this Oth dan of June 1900
CASTLE SMITH,
"Invention" Office, 54, Fleet Street, London, E.C.,
Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Expansion Gear of Steam Engines.
1, GEORGE SELLERS, M.I.M.E., of Wakefield, in the County of Yorkshire,
Consulting 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 :-
This invention relates to several "trip gear" devices to automatically vary the
period of cut off under the control of governors of ordinary or special construction
which latter can be adapted to Corliss, Cornish, piston slide, or gridiron valves of
steam, air, gas or other engines.

page_text: The principal object of this invention is to provide an automatic expansion tri
gear and valve combined capable of being coupled to existing governors so tha
the great cost of a new set of governors may be obviated.
According to this invention I key upon the valve spindle a disc or pulley having
a steel biting bit fitted at a point upon its periphery. Mounted freely upon th
said spindle is a three armed lever the longer arm of which receives a rocking o
oscillating movement from some moving part of the engine to which the device is
fitted. The two shorter arms, which are above the valve spindle, carry triangula
steel triggers pivoted thereto, and the lower ends of which are weighted and res
on the said disc or pulley, one on each side of the biting bit. It will be seen that
by this arrangement, the oscillating movement of the lever is communicated to the
disc and valve spindle so long as the weighted ends of the triggers rest upon the
disc and against the sides of the biting bit. The operation of the governors is made
to raise the triggers from off the disc by presenting an obstruction to the oscillation
of their upwardly extending arms. The governors may act upon the triggers as
described in several different ways. According to one method two stop pins are
carried by a toggle arrangement which is operated by the governor so as to drive
the said stop pins apart and into contact with the upwardly extending arms of the
triggers at different points according to the speed of the engine. According to
another arrangement the governors actuate a right and left handed screw, through
a sector and spur gearing, which gives movement to the stop pins.
The valve is maintained in a normally closed position by means of a spring,
vacuum pot, or other suitable device, so that when the triggers are raised out of
position the valve assumes its closed position.
b
And in order that my invention may be more readily understood and carried into
practice I will now proceed to describe the same with reference to the accompany-
ing two sheets of drawings illustrative of my said invention of which Fig. 1 shows
the herein before described arrangement in which toggle levers are employed.
Keyed upon the valve spindle a is a disc or pulley (shown in dotted lines) having
a steel biting bit c fitted at a point upon its periphery. A three armed lever dis
mounted to rotate freely upon the spindle a its longer arm being slotted at e, to
form an adjustable connection with the rod f through which it receives a rocking
or oscillating movement from some moving part of the engine to which the device
is fitted. To the two shorter arms of the lever d are pivoted triangular steel
triggers the lower ends of which are weighted and rest upon the disc or pulley b,
one upon each side of the biting bit c. With the sides of this bit the triggers
come into contact when the lever d is rocked so that the rocking movement is
communicated through it to the valve spindle a and the valve is thereby
operated. To throw the triggers 9 out of engagement with the biting bit con
the speed of the engine increasing beyond a certain limit the spindle 7, which is
given a longitudinal movement by the operation of the governors, is connected to
the arrangement of toggle levers ; k. These are connected by studs / the
projecting ends of which come into the path of the triggers g when the toggles are
sufficiently extended by the downward movement of the spindle h. The members k
of the toggle arrangement at their lower ends ride freely upon the valve spindle a. It
will be seen that on the spindle h being depressed the studs will be separated so
as to come into contact with the triggers g before they (the triggers) reach the
limit of their reciprocating movement. The continued movement of the lever d
when the upper end of the triggers is stopped will have the effect of raising
the lower ends of the triggers out of contact with the biting bit c so that
the latter may be returned to its normal central position by the action of a
spring, vacuum pot or other device provided for the purpose and which acts to
maintain the valve in a closed position.
In Fig. 2 the triggers are mounted and operated in the same manner as already
described the only difference in this arrangement being the method employed for
throwing the triggers out of action by the operation of the governor. In this
figure it will be seen that the governor spindle h carries at its lower end a rack m

page_text: arranged to move vertically in suitable guides. With this rack gears a pinion n
the spindle p of which is extended on both sides and provided with a screw surface
working in nuts y. The ends of the spindle p are screwed in opposite directions
so that on its being rotated the nuts 9 approach or recede from one another
according to the direction of its rotation. These nuts are pivoted to slotted arms
mounted to turn freely upon the valve spindle a by means of studs s which project
into the path of the triggers g. It will be readily seen that these studs act upon
the triggers in the same manner as the studs shown at Fig. 1.
For operating lift valves I employ the modified arrangement shown at Figs. 3
and 4. According to this arrangement the governor spindle is made to operate
vertically sliding shoes t having inclined or cam faces which when depressed come
into contact with adjusting screws carried by the lifting catches u so that the
same are turned upon their pivots and thrown out of engagement with the cross
head w and the valve allowed to drop on to its seat. As at Fig. 3 the shoes t are
normally held up out of engagement with the lifting catches by the action of a
vacuum pot x. On Fig. 4 a balance weight y is used for this purpose.
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 :-
The hereinbefore described improvements in trip gear for automatically varying
the period of cut offs under the control of governors of ordinary or special con-
struction substantially as hereinbefore set forth and illustrated by the accompanying
drawings.
1
1
1
CASTLE SMITH,
"Invention" Office, 54, Fleet Street, London, E.C.,
Agent for the Applicant.