IMPROVEMENTS IN MODES OF AND APPARATUS FOR WORKING THE SLIDE VALVES OF STEAM AND OTHER ENGINES
Year: 1876

page_text: LETTERS PATENT to Moses Dickinson and David Cullen, both of Bolton, in the
County of Lancaster, for the Invention of "IMPROVEMENTS IN MODES OF AND
APPARATUS FOR WORKING THE SLIDE VALVES OF STEAM AND OTHER
ENGINES."
Sealed the 17th April 1877, and dated the 25th October 1876.
PROVISIONAL SPECIFICATION left by the said Moses Dickinson and David
Cullen at the Office of the Commissioners of Patents on the 25th October
1876.
«
MOSES DICKINSON and DAVID CULLEN, both of Bolton, in the County of
Lancaster. 'IMPROVEMENTS IN MODES OF AND APPARATUS FOR WORKING THE
SLIDE VALVES OF STEAM AND OTHER ENGINES."
Our apparatus as constructed for horizontal engines is as follows:-To the end of
the valve rod of any ordinary slide valve we attach a cross head connected with
another cross head parallel thereto by rigid links, one vertically above the other, at
each end of the cross heads. These cross leads have sliding bars attached to their top
and bottom, and working in slides usually forming the links aforesaid; to the 2nd
cross head, preferably in line with the valve rod, we attach a rod called the buffer
rod hereafter described. On cach cross head we construct a tappet projecting
toward the other; on the same horizontal plane as the valve rod, and at right
angles thereto is a shaft. It could be either the main shaft of the engine or a
counter or intermediate shaft geared to it; on feathers of this shaft slides a single
or double cam, so shaped that in revolving it shall push the valve spindle and buffer
rod by means of the tappets backward and forwards so as to open and close the
valve at the right times. The cam is of varying form, so that by pushing the cam
forward or backward on its shaft and feathers, it can cut off at any required portion
of the stroke. We usually attach the governor to the cam so as to push it back-
ward and forward and thus regulate the admission, applying hand apparatus in the
case of double cams for reversing and throwing the right cam into action. The
same lever that thus reverses the engine can rearrange the governor in its connexion
with the cam; steam or mechanical aids can also be applied to reverse the engine.
D. "77

page_text: The buffer rod already described has two pistons placed loose upon it between
which is a spring. These pistons have trunks round the rod projecting through the
cylinder covers. Two nuts or projections on the rod come against the said trunks,
allowing considerable play between, but not nearly as much as the entire stroke of
the valve rod. The consequence is the spring is compressed at times during the
stroke. The object of this spring arrangement is to more easily, and quickly close
the valve instead of so shaping the cam as to do it. This we prefer to employing
the-cam only, we can however dispense with the spring arrangement entirely.
For other engines than horizontal, the same form of apparatus with very slight
modifications applies. The mode of action is as follows:-The engine is just com-
mencing the forward stroke, the steam port has been thrown wide open by means
of the tappet in the further cross head actuated by cam. The cam in the mean time
has compressed the spring, which remains compressed till the point of cut off on the
cam is reached, that is, till the end of the cylindrical portion of the cam is reached
by the tappet when the latter is released, and the spring flies back and carries the
rods with it, instantaneously cutting off the steam; the same with the return stroke.
The exhaust is unaffected by this arrangement as we unvariably have no lap on the
exhaust, but on the contrary a little clearance.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Moses Dickinson and David Cullen in the Great Seal Patent Office on
the 25th April 1877.
MOSES DICKINSON and DAVID CULLEN, both of Bolton, in the County of
Lancaster. "IMPROVEMENTS IN MODES OF AND APPARATUS FOR WORKING THE
SLIDE VALVES OF STEAM AND OTHER ENGINES."
Our apparatus as constructed for horizontal engines is as follows:-To the end of
the valve rod of any ordinary slide valve we attach a cross head connected with
another cross head parallel thereto by rigid links, one vertically above the other at
each end of the cross heads. These cross heads have sliding bars attached to their
top and bottom, working in slides usually forming the links aforesaid, to the 2nd
cross head, preferably in line with the valve rod, we attach a rod called the buffer
rod hereafter described. On each cross head we construct a tappet projecting
toward the other; on the same horizontal plane as the valve rod, and at right
angles thereto is a shaft. It could be either the main shaft of the engine or a
counter or intermediate shaft geared to it; on feathers on this shaft slides a single
or double cam, so shaped that in revolving it shall push the valve spindle and buffer
rod by means of the tappets backwards and forwards so as to open and close the
valve at the right times. The cam is of varying form, so that by pushing the cam
forward or backward on its shaft and feathers, it can cut off at any required
portion of the stroke. We usually attach the governor to the cam so as to push
it backward and forward and thus regulate the admission, applying hand apparatus
in the case of double cams for reversing and throwing the right cam into action.
The same lever that thus reverses the engine can re-arrange the governor in its con-
nection with the cam; steam or mechanical aids can also be applied to reverse the
engine.
The buffer rod already described has two pistons placed loose upon it between
which is a spring. These pistons have trunks round the rod projecting through the
cylinder covers. Two nuts or projections on the rod come against the said trunks,
allowing considerable play however, but not nearly as much as the entire stroke of
the valve rod. The consequence is the spring is compressed at times during the
stroke. The object of this spring arrangement is to more easily, and quickly close
the valve instead of so shaping the cam as to do it. This we prefer to employing
the cam only, we can however dispense with the spring arrangement entirely.

page_text: EXPLANATION OF DRAWINGS.
This Invention since filing the Provisional application has been successfully
worked, and the Drawings herewith shown except in a few unimportant particulars
are an actual representation of an engine now at work at the Dacca Twist Company's
Mill, of Messrs. Rylands and Sons, Limited, in Bolton. In these Figures, 1 and 2
are vertical elevations with parts in section; Figure 3, an enlarged view of cam.
In these A is the valve chest; B, valve; C, valve rod; D, valve rod cross heads;
E, tappets; F, guide rods; G, guides; H, "buffer rod"; I, J, sliding bushes or
pistons; K, spring in cylinder between sliding bushes; L, M, nuts on the "buffer
rod," that coming against the sliding bushes near both extremes of stroke cause the
said bushes to compress the spring as shown in a very slightly exaggerated form in
the Drawing; N is the cam moveable longitudinally on feathers on the crank shaft,
or as in the present instance on a countershaft geared at equal speeds with it. It is
shown in larger size in Fig. 3 as designed to work with various degrees of expansion,
the exact amount being regulated by the position of the tappets on the cam, the
clutch is actuated by governor O, by means of lever P, or instead of levers
differential gearing can be used, as shown in Drawings at Q, except that with the
depicted position of the balls the friction mitre wheel Q should be in contact with
the upper wheel R rather than the lower, S. In this plan if the balls go too slow
and sink, wheel R touches the wheel Q and sets it going, and thus by convenient
mechanism moves the cam N forward beneath the tappets, thus giving more steam;
if the balls go too fast the lower wheel S comes into gear and draws the cam back,
thus reducing the amount of steam. We do not however make any claim for the
differential governor, as it is old, but merely introduce it to better explain our
Invention.
In the Drawings we have only shown a single cam as the special engine depicted
is not wanted to ever be reversed. When however our valve motion is applied to a
reversing engine, we simply place two of these cams on the same shaft exactly
reversed in every respect so that one shall be right for forward motion, the other for
backward. To reverse the engine one has therefore merely to push the other cam
into play, the same mechanism that pushes the cams forward or backward to reverse
also changing the governor attachment by any of the numerous mechanical
appliances known for this purpose. The cam N on this engine can be oiled by a
spring oiling pad connected with the upper tappet, but in horizontal engines the
kind we prefer for this valve gear the cam can be kept partially immersed in a box
of oil without 'any waste.
Having now particularly described our Invention and the modes of carrying it
into effect, we wish it to be understood that what we claim as our Invention and
desire to protect under the herein-before in part recited Letters Patent is,―
1st. The peculiar construction of the cam N whether single or double, and its com-
bination with the tappets E, E, and the valve rod C or their mechanical equivalents,
substantially as and for the purposes described.
2nd. The combination of the buffer rod H; the nuts or stops M; the sliding bushes
or pistons I, J; and the spring K for the purposes described.

page_text: 3rd. The general arrangement of mechanism, substantially as and for the purposes
described.
4th. The mode of actuating a slide valve, substantially as described.
In witness whereof, we, the said Moses Dickinson and David Cullen, have
hereunto set our hands and seals, this Twenty-first day of April, in the
of our Lord One thousand eight hundred and seventy-seven.
year
MOSES DICKINSON. (L.S.)
DAVID CULLEN.
(L.S.)