IMPROVEMENTS IN DIRECT ACTING STEAM ENGINES FOR PUMPING AND OTHER PURPOSES
Year: 1873

page_text: PROVISIONAL SPECIFICATION left by William Walker, John Walker,
and Samuel Walker at the Office of the Commissioners of Patents,
with their Petition, on the 28th October 1873.
We, WILLIAM WALKER, of Newton Moor, JOHN WALKER, of
Stalybridge, and SAMUEL WALKER, of Dukinfield, all in the County of
Chester, Engineers, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN DIRECT ACTING STEAM ENGINES FOR PUMPING AND OTHER
PURPOSES," to be as follows:-
The principal feature of our Invention relates to a mode of working
the steam expansively in engines where the valve for admitting steam to
the work piston of the engine is actuated directly by steam, such valves
only having motion at or near the end of a stroke of the work
piston.
.
Our Invention consists of the following arrangement and com-
bination: The work piston is formed by a cylinder closed at both
ends longer than the length of the stroke, it has one or more sets of
packing rings at each. end. This work cylinder piston fits a steam
cylinder of ordinary construction (with the exception herein-after
described), which steam cylinder is equal in length to the length of the

page_text: work cylinder piston, plus the length of the stroke. The steam is
brought to a branch in the middle of the steam cylinder which conveys
the steam to the interior of the work cylinder piston through a slot in
the lengthway of its side, and the steam passes from the work cylinder
piston through another slot in its side and through a hole in the side of
the steam cylinder into the valve box and then passes in the usual
manner through ordinary "ports" and passages to act upon the ends of
work cylinder piston.
There are two holes in the side of the steam cylinder for the steam to
pass to the valve chest, one supplying steam to one end the other to the 1
other end of the cylinder, and the length of the slot in the work cylinder
piston which works opposite to the said holes in the sides of the steam
cylinder determines the "cut off" of the supply of steam to the steam
cylinder, and thus the degree of its expansive working.
Arrangements are made where desired for readily changing or varying 1
the length of the said slot in the side of the said work cylinder piston to
vary the "cut off." There is also a slot in the lengthway of the work
cylinder piston into which the end of a tap enters that is screwed into
the steam cylinder, which serves to keep the work cylinder piston from
turning, and to draw off the condensed steam therefrom. There are also 2
two well-know ports and passages in the said work cylinder piston
which open a communication between the exhaust side of the work
cylinder piston and the space in the valve chest at each end of the
piston valve alternately when the work cylinder piston arrives at each
end of its stroke, in which position either one or the other of the two
"ports" in the said work cylinder piston will come opposite a hole in the
side of the steam cylinder that communicates with the space in the valve
chest at that end of the piston valve towards which the valve is next
to be moved.
The valve chest is cylindrical and the valve is a cylindrical piston &
valve, having four piston projections, one at each end, and two which
serve as faces and edges that cover and regulate the immission and
emission of steam to and from the "ports" of the steam cylinder.
The piston valve is hollow but has small holes in its ends and sides, so
that the steam supplied from the work cylinder piston can fill it and
pass to the cavities at each end of the valve chest formed between the
ends of the piston valve and its cylindrical chest.

page_text: The valve receives motion in a well-known manner as before intimated,
when the steam is exhausted from either of the said cavities through the
passages and ports in the work cylinder piston, as the expansion of the
steam in the cavity of the valve chest at the opposite end of the valve
which is not in communication with the exhaust pushes the piston
valve over to the other end of its stroke, the steam being at the timo
more rapidly exhausted from the cavity than it can be replaced through
the small holes provided in the piston valve for restoring the equilibrium
after each movement of the piston valve.