IMPROVEMENTS IN STEAM ENGINES AND BOILERS
Year: 1860

page_text: PROVISIONAL SPECIFICATION left by John Charles Pearce at the Office
of the Commissioners of Patents, with his Petition, on the 31st October
1860.
I, JOHN CHARLES PEARCE, of the Bowling Iron Works, near Bradford, in
the County of York, Engineer, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN STEAM ENGINES AND BOILERS," to be as
follows, that is to say :-
This Invention relates to various improvements in the arrangement and
construction of parts of steam engines and boilers, and comprises modifica-
tions of some of the improvements described in the Specification of Letters
Patent for "Improvements in Apparatus for Generating and Economising
Steam," granted to the present applicant under date the 22nd May 1856,
(No. 1219,) together with additional improvements, the object being generally
to economise fuel, and to render the engine and boiler capable of developing
steadier and increased power.
The improvements in engines relate, firstly, to the construction of metallic
pistons as described in the Specification herein-before referred to, and consist
in making the outer or wearing ring in two parts depthwise, and the inner or
spring rings with wedge-shaped or angular surfaces, so that the combined
elasticity of the latter may exert a constant pressure both laterally and ver-

page_text: tically upon the outer rings, thus keeping them in close contact with the
surface of the cylinder and the flanches of the piston.
The improvements also include a new method of fixing the piston upon the
rod by means of keys driven into suitable grooves formed in the eye of the
piston and the conical part of the rod.
Another portion of the improvements in engines has reference to the
governor or throttle valve. In one modification the valve is composed of two
parts, one of the parts being fixed in a suitably shaped box or casing, and the
other part accurately fitted into or upon it, so as to admit of a rotating or par-
tially rotating and reciprocating movement being communicated to it by means
of a lever attached to the valve spindle outside the casing. Both parts of the
valve are furnished with a series of apertures placed at suitable distances
asunder, so that in one position of the valve all the apertures coincide and
form thoroughfares for the passage of the steam into or out of the casing, as
the case may be. A very slight movement of the lever brings the apertures
of the moveable portion of the valve over or partly over the partitions of the
fixed portion, thus effectually closing or partially closing the thoroughfares, as
circumstances may require, without in any way disturbing the equilibrium of
the valve with regard to the steam pressure. The fixed portion of the valve
is in some cases made to answer the double purpose of seating for both throttle
and stop valve, the latter being conveniently contained in the same casing as
the former.
In another arrangement the valve is made to slide through a double seating,
the latter being composed of one or two parts, as found most convenient. In
this case the apertures of the seating are dispensed with.
The improvements in boilers relate principally to the application of cylin-
drical or other shaped water spaces or vessels to the interior of fire or smoke
flues; such water spaces or vessels being united to the sides of the flues by
rivetted seams running longitudinally, or by metal rings or frames rivetted
between their respective surfaces so as to admit of ample passages for the cir-
culation of the water into and out of the vessels; other parts of the vessels
being further provided with pipes communicating with the water beneath the
flues. The object of these water spaces or vessels being to increase the
evaporative power of the boiler, and the methods of uniting them to the
flues having special reference to convenience for cleaning their respective
surfaces.
Another portion of these improvements consists in constructing the furnace
grate bars with two longitudinal parts connected together by a series of light

page_text: cross ribs, with a view to secure a large area for the passage of air to the
burning fuel, and to economise the material of the bars.
A further improvement in boilers consists in a peculiarly constructed safety
plug, composed partly of tin or other easily fused metal or alloy, fitted into or
cast upon a seating of iron or other hard metal, by means of which it is
secured or otherwise fitted into a suitable hole formed in that part of the
boiler most liable to injury from deficiency of water and over-heating.