Improvements in the Expansion Gear of Steam Engines.
Year: 1890

page_text: Date of Application, 5th May, 1890
Complete Specification Left, 4th Feb., 1891-Accepted, 21st Mar., 1891
PROVISIONAL SPECIFICATION.
Improvements in the Expansion Gear of Steam Engines.
I, WILLIAM WALKER, of 12, Holly Street, Eccles New Road, Salford,
Manchester, Mechanical Engineer, do hereby declare the nature of this invention
to be as follows :-
My invention consists in what is commonly known as trip gear, the period of
cut-off being automatically controlled by the governor. My arrangement is
particularly applicable to existing engines, and I may actuate by this mechanism,
#: cross
either drop valves of "Cornish" construction, or what is generally termed a
rid" valve, working transversely to the motion of the main slide valve.
I use a hollow sleeve of suitable diameter, which is made to oscillate to and fro
by a lever from any convenient part of the engine.
Within this hollow sleeve (which is bored out) are two discs, the said discs being
driven in either direction by means of a detent piece, through the said hollow
sleeve.
On each of these discs is a pin which lift the cut-off valve alternately. On the
same pin is mounted a bell crank lever, the longer end being of curvilinear form,
and its short end "toggle" shaped, the said toggle" being embraced by the
detent piece, which is fixed on each disc, and made to slide out of gear radially
from the motion imparted to it by the hollow sleeve, at varying periods determined
by the governor.
This period of sliding out of gear of the detent piece, and consequent time of
"release" or ແ tripping," simply depends upon each curvilinear end of the bell
crank lever, reaching a sliding pin sooner or later, the said sliding pin being raised
or lowered by the governor; and when either of the bell crank lever ends come in
contact with the governor pin, one or other of the detents (as the case may be) is
made to quit or leave its driving edge radially, and the valve is quickly but quietly
closed, through the intervention of the ordinary "dashpot."
The point at which the sliding detent again enters radially into gear by use of a
spring, always occurs at a time, when the working lever of the hollow sleeve is in
its normal position or slowest travel, and consequently an almost noiseless action is
maintained.
Dated this 3rd day of May 1890
WILLIAM WALKER.
COMPLETE SPECIFICATION.
Improvements in the Expansion Gear of Steam Engines.
WILLIAM WALKER, 12, Holly Street, Eccles New Road, Salford, Manchester,
Mechanical 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 consists in what is commonly known as "trip gear" the period of
cut-off being automatically controlled by the governor.
My arrangement is particularly applicable to existing engines, and I may operate
by this mechanisin either a drop valve of Cornish construction, or what is generally
termed a cross grid" valve, working transversely to the motion of the main slide
兹
valve.

page_text: I use a hollow sleeve of suitable diameter which is made to oscillate to and fro
by a lever actuated from any convenient part of the engine.
Within this hollow sleeve (which is bored out) are two discs, the said discs
being driven in either direction by means of a detent piece through the said hollow
sleeve.
On each of these discs, is a pin which lift the ent-off valve alternately. On the
same pin is mounted a bell erank lever the longer end being of curvilinear form,
and its short end toggle shapel, the said toggle being embraced by the detent piece
which is fixed on each disc, and mude to slide out of gear radially, from the motion
imparted to it by the hollow sleeve, at varying periods determined by the
governor.
This period of sliding out of gear of the detent piece, and consequent time of
release" or tripping, simply depends upon each curvilinear end of the bell crank
lever reaching a sliding pin sooner or later, the said sliding pin being raised or
lowered by the governor, and when either of the bell crank lever ends come in
contact with the governor pin, one or other of the detents (as the case may be) is
made to quit or leave its driving edge radially and the valve is quickly but quietly
closed through the intervention of the ordinary dashpot.
The point at which the sliding detent again enters radially into gear by use of
a spring, always occurs at a time when the working lever of the hollow sleeve is in
its normal position or slowest travel, and consequently an almost noiseless action is
maintained.
Figs. 1 & 2 on the necompanying drawing shews a l'orter governor (A) driven
in the usual manner, and (B) à easing containing a Cornish or "drop" valve by
preference.
(C) is a spring dash pot with air snifting valve (D). for regulating the velocity
of closing, and the degree of cushioning the said Cornish valve upon its release
hereafter described.
The working lever (E) Figs. 2 and 3 is keyed on to the hollow sleeve (F), which
is of one casting, and this hollow sleeve has a constant to and fro motion imparted
to it from the engine. In Fig. 3 the hollow sleeve (F) is shown in the position of
beginning to drive the dise (0) from right to left, and lift the said Cornish valve.
by means of the pin (H) upon which the said curvilinear bell crank, or detent
lever (G) is mounted, the lifting plate (1) resting upon the said pin (11) also.
This lifting of the Cornish valve continues until the curvilinear part of the bell
crank or detent lever (G) reaches the governor pin (J), upon which the toggle end
of the said detent levor (G) is forced away from the driving edge (M) of the hollow
sleeve (F) in the direction shewn by the arrow, whereupon the tripping or release
of the parts driven, causes the Cornish valve to return to its seat at a time sooner
or later, according to the location of the vertical height of the governor pin (J).
The saine action obtains with the other disc (01) and its similar mountings, or
counterparts, but of an opposite hand to those already described and specified,
so as to give two lifts of the Cornish valve for each revolution of the engine.
The detent slides (of circular form) marked (T) and (T) contained in the
dises (0) and (01) have a spring in cach, whereby the curvilinear bell crank, or
detent levers (G) and (G) are alternately brought into position with their
respective driving faces at every back stroke of the hollow sleeve (F) as shewn in
the case of the said detent lever (G) in Fig. 3.
Figs. 4 & 5 shew my invention as applied for the tripping or release of Corliss
valves, or a well known type of valve on the "cross grid" principle, the mechanism
for this purpose being arranged under the same conditions and circumstances as
already described.
(P) and (F) are the governor pins which are made to move to and fro longi-
tudinally by the governor rod (R) according to the load on the engine, and thereby
vary the period when the bell crank detent levers (G) and (G) come into contact
with the said pins (P) and (P), and so effect the release or closing of the valves,
thereby altering the point of cut-off' accordingly.

page_text: 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 :-
1st. In valve gear of the kind herein before named, a curvilinear bell crank lever
or levers with a toggle end, and working on a single pin joint or its equivalent,
substantially as and for the purpose herein before described.
2nd. In valve gear of the kind hereinbefore described, a curvilinear bell crank
lever or levers, being kept into its driving position by a spring enclosed in a circular
detent box, substantially as and for the purpose hereinbefore described.
3rd. A hollow sleeve having within it a driving disc in connection with a curvi-
linear bell crank lever, and sliding detent piece, substantially as and for the purpose
hereinbefore described.
Dated this 2nd dow of Tabur 1801
WILLIAM WALKER.