Improvements in Automatic Expansion Gear for Steam Engines.
Year: 1887

page_text: Date of Application, 15th Jan., 1887
Specification Accepted. 29th Mar., 1887.
COMPLETE SPECIFICATION.
Improvements in Automatic Expansion Gear for Steam Engines.
We ALBERT HOLT and JOHN THOMAS HOLT both of Hume Street Works off
Crawford Street Rochdale in the County of Lancaster Engineers do hereby declare
the nature of of our invention for "IMPROVEMENTS IN AUTOMATIC EXPANSION GEAR
FOR STEAM ENGINES," and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :-
Our invention relates to apparatus for governing the admission of steam into the
cylinders of steam engines, being connected to the cut off valve, and under the control
of the governor, and is so adapted and arranged, that when the engine attains or
diminishes speed beyond or below its proper speed, the cut off valve is caused to be
actuated; so that steam may be cut off from, or admitted into the cylinder as the case
may be and as may be required in order to maintain the proper speed of the engine.
In order that our invention may be better understood we have reference to the
accompanying sheet of drawings in which our invention is fully illustrated, and
wherein like letters of reference indicate like parts throughout the same.
Fig. 1 is a side elevation.
Fig. 2 is a front elevation of cam arrangement.
Fig. 3 is a plan.
Fig. 4 is an end elevation.
Fig. 5 is a sectional view shewing method of securing screw wheel to the governor
sleeve.
At the lower part of the governor sleeve p we provide a collar A, which carries a
peculiar toothed wheel b being secured thereto by means of screw threaded pieces C,
the wheel b is caused to gear with a corresponding tooth wheel d axially provided on
the horizontal shaft e; which shaft is provided with a cam j, and carried by a bracket
or box i situated at the upper part of the governor stand; and which we term for
convenience of description "cam shaft" the said wheel d is adapted so as to slide in
either direction upon the said shaft, the means which we employ so as to allow the
said wheel to slide therein we will now proceed to describe.

page_text: On the cam shaft is loosely mounted a collar that is the collar is not secured to
the shaft having at one end an annular rim the wheel d is bored out and fitted on
to the collar by suitable means; the collar being provided with slots h. ¹ one on the
upper side, and one on the lower side, into each of which enters the extremities of a
key g. fitted to the cam shaft; on the cam shaft is also provided another collar,
having at one end an annular rim, the face or outer part of which is situated next to
the face or outer part of the rim of the collar, the said collar a being coupled to the
collar by means of a circular piece A', preferably of brass, and affixed to the face
part of the rim f' by means of screw threaded pieces A2, being suitably recessed to
accomodate the annular portion of the collar, such method of coupling allows the
collar to rotate with the cam shaft.
When motion is imparted to the wheel d. by the agency of the wheel b, the cam
shaft is consequently caused to revolve, the cam is then caused to act alternately upon two
bowls K. K mounted on the lever ; the said lever being connected to the spindle O
by means of levers M. N, and the spindle O being connected by means of a convenient
lever or levers to the cut off valve of the enjine, which valve may be of any
ordinary type the action of the cam on the bowls K. K¹ produces a reciprocating
motion to the lever l, consequently the spindle O is similarly actuated, and suitably so,
in order to allow the cut off valve to perform its proper functions which are well known.
We will now describe the mechanism or parts connecting the wheel d and its
appendages with the governor sleeve p.
At the upper part of the governor sleeve p levers pl p¹ engage therewith, one on each
side, being supported and carried by a spindles and free to turn in its bearings t. t'; the
spindle is provided at one extremity with a quadrant tooth wheel u, which we term for
convenience of description "quadrant" the said quadrant is caused to gear with a
toothed rack on the upper side of a horizontal sliding bar, a tooth wheel w provided
on one extremity of the shaft is caused to gear with a toothed rack at the under side
of the said sliding bar see Fig. 1, on the shaft is also provided another tooth wheel y',
which is caused to engage with a toothed rack y situated at the underside of the collar
which
see Fig. 4 when the sleeve p is caused to rise or fall on the spindle p. P
motions may be due to an accelerated or retarded velocity of the enjine, the
wheel d and its appendages is then instantly operated upon and thus caused to
slide on the cam shaft, by the agency of the mechanism of which the levers p¹p",
quadrant u, and rack vare a part and before described.
:
The sliding motion of the wheel d, being simultaneous with the sliding motion of
the wheel b, forms the essential feature of our invention; the said wheel d and
its appendages being under the influence of the movements of the sleeve p, and
arranged as described so as to move immediately on the shaft in the event of a
rise or fall of the said sleeve. We effect by such means an immediate variation
of velocity of rotation of the cam shaft, quickly or slowly, accordingly as the
wheel d is caused to travel in direction with, or in direction contrary to the motion of
the wheel on the spindle p. p, in the first case the motion of the cam shaft is
accelerated, in the second case the motion of the said shaft is retarded, such motions
being imparted to the cut off valve allows steam to be admitted into the cylinder
earlier or later as the case may be, and as may be required in order to maintain a
regular motion or the efficiency of the engine.
We would have it understood that we do not confine ourselves to the exact details
as herein shewn, as it may be necessary to depart therefrom without deviating from
tho principle thereof; as for instance, the mechanism for sliding wheel d on shaft e
may consist of any other convenient gearing and suitable disposition or arrangement
of levers.
Having now particulary described and ascertained the nature of our said invention
and in what manner the same is to be performed, we declare that what we claim is.
1. In an automatic expansion gear for steam engines the simultaneous sliding
actions of the wheels band d on the spindle and cam shaft respectively, and adapted

page_text: so that each wheel may move equal distances in the direction of their axes substantially
as and for the purposes herein fully set forth and described in the annexed drawings.
2. The use and application of a piece on the shaft e at any convenient part thereof,
and carrying a wheel d; adapted so as to both to slide on, and rotate with the said shaft,
the said piece being coupled to a sliding piece, by means of a circular piece a¹, and
screw threaded pieces a³, substantially as and for the purposes herein fully sot forth and
described in the annexed drawings.
3. The combination of the mechanisın consisting of levers p¹p", spindlos,
quadrant u, sliding bar, wheel w, shaft z, and wheel y", with the connected sliding
pieces on shaft e, and detailed in above claim, substantially as and for the purposes
herein fully set forth and described in the annexed drawings.
Dated this 14th day of January 1887
JOHN H. BUTTERWORTH,
Agent for the Applicants.