Improvements in Valve Gear for Steam Engines.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in Valve Gear for Steam Engines.
I, NOËL CHANDLER, of Cannock Chase Foundry and Engine Works, Hednes-
ford, in the County of Stafford, Engineer, do hereby declare the nature of this
invention to be as follows:-
This invention has reference to improvements in valve gear for steam engines
whereby a better distribution of steam can be obtained than by the use of
ordinary eccentric discs and straps, which, according to this invention, are
dispensed with thereby enabling the overall length, i.e. the total length
measured along the crank shaft of two or more crank engines to be reduced by
reason of there being no space occupied on the said crank shaft by the width of
the eccentrics, a further advantage being the absence of friction due to the use
of eccentrics which is a matter of great importance especially in the case of
high speed engines.
For this purpose according to this invention there is loosely pivoted to the crank
pin end of the connecting rod of an engine, or it may be to a part carried by
the crank pin or to the crank pin itself, one end of a coupling rod the other end
of which is loosely jointed to a two armed rocking lever or the like which is
pivotally mounted on a stationary part of the engine, at a suitable point inter-
mediate of its length, the bearings forming the fulcrum of the lever.
other end of the rocking lever is connected by means of a link to the valve rod.
The arrangement is such that the first mentioned end of the coupling rod is
constrained to move in a suitable path whereby motion is transmitted through
the rocking lever and connecting link to the valve spindle.
The
In one arrangement of valve gear in accordance with this invention as applied
for example to a compound vertical steam engine with the high and low pressure
cylinders arranged one above the other and worked by means of balanced piston
valves, the lower end of the connecting rod of the engine, i.e. the end carried by
the crank pin, is provided with lugs or bracket portions that carry a horizontal
pin upon which is loosely mounted the lower end of a coupling rod the upper
end of which is connected to one arm of a rocking lever the other arm being
suitably connected to the lower end of a link the other end of which is jointed
to the valve rod. The gudgeon of the said lever acting as the fulcrum is mounted
upon adjustable bearings to compensate for wear. The coupling rod is con-
veniently constructed so that adjustment can be made to take up wear at both
ends thereof.
With the arrangement described, the lower end of the coupling rod travels in
an elliptical path which is eccentric to the crank shaft whereby a suitable
movement is transmitted to the valves of the engine.
This invention is particularly applicable to single acting engines of the

page_text: closed-in type similar to those described in the Specifications of former Letters
Patent granted to me for example Nos. 5076 and 14419 of 1890; 2621 of 1893;
9606 of 1894; and 22631 of 1896, steam being admitted to the cylinders from
above the piston valves and exhausted below.
Improvements in Valve Gear for Steam Engines.
I, NOEL CHANDLER, of Cannock Chase Foundry and Engine Works, Hednes-
ford, in the County of Stafford, 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:-
are
This invention has reference to improvements in valve gear for steam engines
such as previously patented by me as herein after referred to whereby a better
distribution of steam can be obtained than by the use in such engines of
ordinary eccentric dises and straps, which, according to this invention
dispensed with, in my said engines thereby enabling the overall length, i.e. the
total length measured along the crank shaft of my two or more crank engines to be
reduced by reason of there being no space occupied on the said crank shaft by
the width of the eccentrics, a further advantage being the absence of friction due
to the use of eccentrics which is a matter of great importance, especially in the
case of high speed engines.
For this purpose according to this invention in an engine of the kind men-
tioned there is loosely pivoted to the crank pin end of the connecting rod of the
engine, or it may be to a part carried by the crank pin, or to the crank pin
itself, one end of a coupling rod the other end of which is loosely jointed to a
two armed rocking lever which is pivotally mounted on a stationary part of the
engine, at a suitable point intermediate of its length, the bearings forming the
fulcrum of the lever. The other end of the rocking lever is connected by means
of a link to the valve rod. The arrangement is such that the first mentioned end
of the coupling rod is constrained to move in a suitable path whereby motion
is transmitted through the rocking lever and connecting link to the valve
spindle.
The accompanying drawing shows partly in vertical cross section and partly
in elevation, the lower portion of a vertical steam engine of the kind referred
to provided with valve gear according to this invention.
On the lower end of the connecting rod 1 jointed to the crank pin 2, are formed
lugs or brackets 1" that carry a horizontal pin 3 to which is jointed the lower end
of a coupling rod 4 the upper end of which is jointed to one arm of a rocking
lever 5 the other arm of which is connected through a link to the valve rod 7.
The gudgeon or axle 8 of the rocking lever 5, which acts as a fulcrum, is mounted
in bearings 9 which can be adjusted so as to compensate for wear. Also the
coupling rod 4 may be made adjustable in length to compensate for wear at the
ends thereof.
With the arrangement illustrated, the lower jointed end of the coupling rod 4
travels in an elliptical path eccentric to the crank shaft, whereby a suitable

page_text: movement is obtained through the coupling rod 4, rocking lever 5, and link 6
for working the valve rod 7 and the valves connected therewith.
I know.it has been proposed to operate the valves of steam engines through
levers connected by links to the connecting rods and valve spindles but according
to this invention I apply the arrangement of valve gear described in the manner
illustrated to single acting engines of the closed in type similar to those described
in the Specifications of former Letters Patent granted to me Nos. 2621 of
1893 9606 of 1894; and 22631 of 1896, steam being admitted to the cylinders
above the pistons from above the piston valves and exhausted below.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I wish to have it
distinctly understood that I do not claim broadly operating the valves of steam
engines through levers connected by links to the connecting rods and valve
spindles but my invention is limited to the described application of such valve
gear in engines of the kind referred to in which the steam is admitted to the
cylinders above the pistons from above the piston valves and exhausted below
and I declare that what claim is:
In a single acting steam engine of the type hereinabove referred to wherein
steam is admitted to the cylinder from above the piston valve, i.e. that end
thereof furthest from the crank shaft and exhausted below, i.e. at that end
of the valve nearest to the crank shaft, valve gear comprising a two-arm rocking
lever mounted on a stationary part of the engine and having one of its arms
connected through a coupling rod to the crank pin end of the engine connecting
rod, or to the crank pin, or to a part carried thereby, and its other arm connected
to the valve rod, as described with reference to and shewn in the drawing.
Dated this 7th day of Decembar 1808