IMPROVEMENTS IN THE CUT-OFF MOTION AND SLIDE VALVES OF STEAM ENGINES
Year: 1860

page_text: PROVISIONAL SPECIFICATION left by Alfred Vincent Newton at the Office
of the Commissioners of Patents, with his Petition, on the 3rd January
1860. A communication from abroad by Charles Auguste Schultz and
John Hauck, both of New York, in the United States of America.
I, ALFRED VINCENT NEWTON, of the Office for Patents, 66, Chancery Lane,
in the County of Middlesex, Mechanical Draughtsman, do hereby declare the
nature of the said Invention for "IMPROVEMENTS IN THE CUT-OFF MOTION AND
SLIDE VALVES OF STEAM ENGINES," to be as follows:-
This Invention relates to an arrangement of face cams, which are relatively
adjustable by means of a V-shaped yoke for operating the slide valves of steam
engines, and thereby cutting off the steam at any desirable part of the stroke.
And the Invention also relates to a certain novel arrangement of the slide
valve, whereby the pressure of the steam exerted on the valve in one direction
is balanced by the pressure against the top of the valve in the other direction.
The body of the balance slide valve is similar to the ordinary slide valve, but
from it rise four columns supporting a flat plate. Fitted steam-tight over this
plate is a cap, which is allowed to move up and down freely. The columns are
made hollow to contain springs which force the cap up against the cover of the
steam chest and the valve down on its seat: If, therefore, the area of the plate
is made equal to the superficial area of the valve, the latter will be perfectly
balanced, no steam being allowed to come between the cap and the plate, or
between the cap and the cover of the steam chest.
The valve is operated by means of a tappet rod connected with the valve

page_text: stem by a clutch. Between the tappets on this rod works a double cam, which
is secured to a rotary shaft, placed in suitable bearings on the side of the frame,
and deriving its motion from the crank shaft of the engine.
The double cam consists of two parts placed one inside the other, one being
for opening, and the other for cutting off the steam; each of the cams is provided
with a hole and with a slot, the hole in the one cam being opposite to the slot
of the other cam. Through these openings the two prongs of a bent V-shaped
yoke pass freely, and when moved in a longitudinal direction the relative
positions of the cams is changed, and the steam is consequently cut off at an
earlier or later stage of the stroke. This yoke is attached to a sleeve that
slides on the cam shaft, and it connects by means of a forked pointer with a
screw rod that slides in two standards. The hub of the pointer is tapped to
work on the screw rod, and the pointer moves over a fixed scale, to indicate
the part of the stroke at which steam is cut off. This screw rod connects by
means of a crank lever with the governor, so that when the speed of the
engine increases, and the balls of the governor fly out, a sliding motion is im-
parted to the rod in the direction from the cylinder, thereby increasing the
distance between the sleeve and double cam, and causing the steam to be
cut off at an earlier stage of the stroke. The position of the sleeve with the
yoke is adjusted by turning the screw rod, so as to bring the forked pointer
nearer to or further from the cylinder, and the speed of the governor is so
adjusted, that it instantly corrects any variation in the speed of the engine from
work being put on or thrown off, or from other causes.