Improvements in Valve Gear of Steam and other Fluid Motors.
Year: 1894

page_text: Date of Application, 20th Apr., 1894-Accepted, 16th June, 1894
COMPLETE SPECIFICATION.
Improvements in Valve Gear of Steam and other Fluid Motors.
We, GORDON MCDAKIN CLENCH, of The Lincoln Engine Works, Chesterfield,
and THOMAS SCOTT KING, of Stanley Street, Spital, Chesterfield, in the County
of Derby, Engineers, 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 :-
The object of this invention is the improvement and simplification of valve gears
for steam and other fluid motors, and more particularly that type of engine having
double beat valves worked by trip motion, and having the point of release
regulated automatically by some mechanical combination, such as a governor, or by
hand.
Figure 1, Sheet 1, of the annexed drawings is a sectional elevation showing the
general arrangements of trip mechanism in a locked position.
Figure 2, Sheet 2, is a sectional elevation showing the trip mechanism and general
arrangements as applied to the cylinder of an engine upon a reduced scale.
Figure 3 is a similar elevation showing the trip mechanism disengaged and the
valve closed.
Figures 4 and 5 are modifications of the trip mechanism.
In a bored recess of the cylinder A is a double beat valve seat B and a double
beat valve C. The valve spindle D working in the gland E is lifted by a lever F
which receives its motion from a mechanical arrangement to be hereinafter
described. When the spindle D is lifted, the valve C is opened for admission of
steam to the cylinder A. The valve C is closed by the pressure of steam on the
unbalanced area of the valve and by the pressure of a spring G which acts on the
top of the air piston H.
The air piston H is retarded in its descent by a volume of air automatically
trapped in the space between the piston H and the bottom of the air cushion box I,
the expulsion of the air being controlled by a small screw in a hole, a ball valve, or
other means, so as to enable the engine attendant to cause the valve to seat itself
without shock or noise.
The valve gear is operated from an eccentric J, crank, or other mechanical means
suitable for the purpose, and is connected by the rod K to the pin L in the outer
end of the radius links M and imparts a vibratory motion thereto about the pin L
as centre.
Suspended from the coupling pin L is a trip catch link N which is provided
with a hardened steel catch piece P to engage with a similar steel catch piece Q on
the trip lever F.
When the links M are at their highest point, and the valve is on its seat, as at
Figure 3, there is room for the link N to swing in towards the lever F, so that
when M is pulled down by the eccentric rod K, the steel catch piece on N engages
with the steel catch piece on F, and the three pieces F, M, N, become a locked
triangle moving about a common centre R.
The continued downward movement of the swing links M and consequently of
the lock triangle F, M, N, will cause the knock out roller S at the end of the trip
catch link N at some point on the downward stroke to come in contact with the
knocking out cam T. Previous to S coming in contact with T, S has moved on a
curve generated from the centre R. After S touches T, the path of the roller S
will coincide with the contour of the cam T, which being divergent outwardly from
the centre R, will cause the steel face on N to draw off the steel face on F, and

page_text: so release the valve, which will return to its seat in the manner hereinbefore
described.
The period during which the steel faces will be drawing asunder is determined by
the angle formed by the contour of the cam T to the curve which the roller Ŕ
describes when part of the locked triangle F, M, and N. The more obtuse the
angle, the more slowly will the steel faces draw apart.
By moving the cam or knock out piece T about the centre U by means of a
lever V (which can be done automatically by a governor, or by hand), the point at
which the trip lever is released may be varied. Thus, by depressing the lever V,
as at Figure 3, the roller S comes in contact with the cam T at an earlier point in
the downward movement of the locked triangle F, M, and N, and the lever F is
therefore released earlier. If the lever V is raised, the release of the trip lever
takes place at a later point.
The arrangement of knock out cam T and roller S may be modified in the manner
shown in Figure 4 in which there is an inclined plane S at the end of trip catch
link N and a knock out roller T¹ on the knock out lever V; or as in Figure 5
which shows an inclined plane S¹ at the end of the trip catch link N and a knock
out cam T on the lever V.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
1. The improvements in valve gear of steam and other fluid motors consisting
of the combination of parts F, M, N, with the arrangement of the knock out roller
on the end of the trip catch link, and the knock out cam on the cam shaft or
regulating shaft, as described and substantially as shown in the drawings.
2. In trip valve gears of steam and other fluid motors, the arrangement of knock
out cam T on the cam or regulating shaft U and knock out roller S on the trip
catch link N, as in Figures 1, 2, and 3, or the modification of same shown in
Figures 4 and 5 of the annexed drawings.
Dated this 20th day of April 1894.
H. GARDNER,
166, Fleet Street, London, Patent Agent,
Agent for the said Gordon M Dakin Clench and Thomas Scott King