IMPROVEMENTS IN REGULATING APPARATUS FOR STEAM ENGINES
Year: 1882

page_text: LETTERS PATENT to Henry Davey of Headingly near Leeds in the County
of York for an Invention of IMPROVEMENTS IN REGULATING APPARATUS
FOR STEAM ENGINES
PROVISIONAL SPECIFICATION left by the said Henry Davey at the Office
of the Cominissioners of Patents on the 9th August 1882.
HENRY DAVEY of Headingly near Leeds in the County of York
IN REGULATING APPARATUS FOR STEAM ENGINES"
"IMPROVEMENTS
My invention relates to means of controlling steam engines, especially direct
acting pumping engines under great variations of resistance. For this purpose I
provide either in the inlet or outlet passage of the engine or in the case of a
compound engine in the passage between the two cylinders, a valve which in the
ordinary working of the engine is kept open by a catch, held by a trigger. By the
movement of this trigger the catch can be released permitting the valve to close.
The trigger is worked in the following manner :-A cataract cylinder charged with
water or other suitable liquid has a passage from one end to the other which can
be regulated by a cock or valve. The piston of the cataract cylinder is connected
to a moving part of the engine through a differential lever. One end of this lever
receives motion from the engine piston on a reduced scale, the opposite end actuates
the trigger of the valve by a tappet rod, and to an intermediate point of the lever
the cataract piston is linked. The tappet rod, when the engine is at rest, is held in
middle position by two springs opposing each other. The motion of the cataract
piston, is opposed by the resistance to the flow of the liquid which can be adjusted
as desired; when this resistance exceeds the resistance of either spring, motion is
imparted to the tappet rod, and this releases the trigger so that the valve closes.
Thus in case of a sudden increase in the velocity of the engine, the steam passage
is closed and the engine is retarded or stopped.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Henry Davey in the Great Seal Patent Office on the 8th
February 1883.
HENRY DAVEY of Headingly near Leeds in the County of York
IN REGULATING APPARATUS FOR STEAM ENGINES
"
"IMPROVEMENTS
My invention relates to means of controlling steam engines, especially direct
acting pumping engines under great variations of resistance.
For this purpose I
provide either in the inlet or outlet passage of the engine or in the case of a
compound engine in the passage between the two cylinders, a valve which in the
ordinary working of the engine is kept open by a catch, held by a trigger. By the
movement of this trigger the catch can be released permitting the valve to close.
The trigger is worked in the following manner:-A cataract cylinder charged with
water or other suitable liquid has a passage from one end to the other which can
be regulated by a cock or valve. The piston of the cataract cylinder is connected
to a moving part of the engine through a differential lever. One end of this lever
receives motion from the engine piston on a reduced scale, the opposite end actuates
the trigger of the valve by a tappet rod, and to an intermediate point of the lever
the cataract piston is linked. The tappet rod, when the engine is at rest, is held in
middle position by two springs opposing each other. The motion of the cataract
piston is opposed by the resistance to the flow of the liquid which can be adjusted
as desired; when this resistance exceeds the resistance of either spring, motion is
imparted to the tappet rod, and this releases the trigger so that the valve closes.
Thus in case of a sudden increase in the velocity of the engine, the steam passage
is closed and the engine is retarded or stopped.
The accompanying drawing is a longitudinal section shewing regulating apparatus
according to my invention applied to operate a valve V which may be of the double
beat kind, as shewn, situated in the pipe connecting the high and low pressure
cylinders of a compound engine, but which might be a valve of other form situated
in either the supply or the discharge pipe of a simple engine.
A rod A connected to a lever, worked by any convenient reciprocating part of
the engine such as the piston rod cross head, gives reciprocating motion to one arm
of a differential lever B. This lever about its middle is jointed to the piston rod of
a cataract cylinder C containing liquid with which it may be charged from a vessel D.
The two ends of the cylinder C communicate by a pas age in which there is a cock
or valve E whereby the flow of liquid can be more or less throttled. The upper
arm of the lever B is jointed to a rod F which is held stationary with a certain
degree of firmness by means of two springs G adjustable by nuts g. The rod F has
a guided continuation H jointed to it, this rod having fixed on it two tappets h h,
one on each side of a trigger K, which in its middle position has a hooked end
engaging under a sloped collar L on the rod of the valve V, but which, when it is
pushed in either direction, becomes disengaged from the collar allowing the valve V
to close. The cock or valve E and the springs G being properly adjusted and the
valve V being held open by the trigger K in its middle position, if the engine move
at such a rate that the resistance offered to the piston of the cataract cylinder C by
the passage of liquid from one end of it to the other, does not exceel the effort of
the springs G to keep the rod F at rest, then the lever B merely oscillates on its
upper pin at F as a fulcrum. But should the engine race, tending to make the
movement of the citaract piston more rapid and so to increase the resistance of the
liquid to its movement, then the upper end of the lever B will be caused to oscillate,
and if the oscillation should be such that either of the tappets encounters the
trigger K, the trigger will be pushed aside releasing the valve rod and so allowing
the valve V to close, thereby effecting retardation or stoppage of the engine.

page_text: Having thus described the nature of my invention and in what manner the same
is to be performed, I claim :-
For the purpose of controlling an engine under great variation of resistance, the
use of regulating apparatus consisting of a valve held open by a trigger subject to
the releasing action of tappets, the movement of which is determined by a
differential lever moved by the engine and resisted by a cataract piston,
substantially as herein described.
In Witness whereof I the said Henry Davey have hereunto set my hand
and seal this Seventh day of February in the year of our Lord One thousand
eight hundred and eighty-three.
HENRY DAVEY (L.S.)