IMPROVEMENTS IN GOVERNORS AND SLIDE VALVES
Year: 1874

page_text: LETTERS PATENT to Arthur Rigg, Engineer, of Number 1, Fen-
church Street, London, E.C., for the Invention of "IMPROVEMENTS
IN GOVERNORS AND SLIDE VALVES."
Sealed the 20th April 1875, and dated the 23rd October 1874.
PROVISIONAL SPECIFICATION left by the said Arthur Rigg at the
Office of the Commissioners of Patents, with his Petition, on the
23rd October 1874.
I, ARTHUR RIGG, Engineer, of Number 1, Fenchurch Street,
London, E.C., do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN GOVERNORS AND SLIDE VALVES," to be as follows:-
My Invention relates to improved arrangements of governor to
regulate the speed of an engine by altering the position of an eccentric
driving slide or expansion valves, or acting in any other suitable manner
to regulate the expansion of an elastic fluid, to an improved arrange-
ment of expansion valve, and to an improved slide valve.
I employ one or other of the governors described in the Specification
of a Patent granted to me for "Improvements in Regulators of Speed'or
->

page_text: Power, applicable Partly to Engines and Partly to other Machinery,"
bearing date the Sixteenth day of December, One thousand eight hundred
and seventy-two, but in addition where necessary I balance its moving
parts to neutralize the effect of gravity. Or else I make use of the
following improved arrangement based upon the construction described
under Figures Five and Six in the Specification already referred to,
instead of a groove N, O, and pin O I fix on each side of the fork F
inclined or wedge-shaped pieces, whose inclined surfaces are parallel to
each other, and fit between projections on an excentric so mounted as to
slide in a direction at about right angles to the slide on which the
governor moves, and any change in position of the latter causes a
movement of the excentric to a less extent, or inclines may be fixed on
the excentric.
The effect of gravity on the moving parts of these governors may be
neutralised directly by balance weights when required, but I prefer to
construct the strap and weight to balance each other by connecting them
by levers or otherwise, or else I give an end pressure to the valve
spindle in such a direction as tends to lift the moving parts of the
governor, and this end pressure may got by an enlargement of the
valve spindle, where it passes through the gland, or by other means.
Where in double cylinder engines each cylinder has its own expansion
valve, I prefer to use one governor and to move the second excentric
from the one connected with this governor, or else I work both valves
from one excentric by suitable connections.
In constructing an expansion valve to use with the governor arrange-
ments described or otherwise, I prefer that it slide over ports on the
back of a slide valve, or else work as a piston valve within it. Each
expansion valve is formed in two parts capable of being fixed at a
suitable distance asunder in order to adjust the lap, and an expansion
valve thus arranged is driven by an excentric having its position
variable.
In slide valves working under high pressures I enlarge the bearing
surface and cut channels, separating the additional portion from the
ordinary valve surface. These channels communicate with the inlet,
and they may be cut on the valve itself or on the surface upon which it
slides. This construction may be applied to any valves sliding on

page_text: surfaces, whether their movement be straight or circular, moveover the
additional surface need not necessarily be in the same plane as the valve
face.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Arthur Rigg in the Great Seal Patent Office on
the 22nd April 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ARTHUR
RIGG, of Number One, Fenchurch Street, London, E.C., send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-third day of October, in the year
of our Lord One thousand eight hundred and seventy-four, in the thirty-
seventh year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Arthur Rigg, Her special licence that
I, the said Arthur Rigg, my exccutors, administrators, and assigns, or
such others as I, the said Arthur Rigg, my executors, administrators,
and assigns, should at any time agree with, and no others, from time
to time and at all times thercafter during the term therein expressed,
should and lawfully might make, use, exercise, and vend, within the
United Kingdom of Great Britain and Ireland, the Channel Islands,
and Isle of Man, an Invention for "IMPROVEMENTS IN GOVERNORS AND
SLIDE VALVES," upon the condition (amongst others) that I, the said
Arthur Rigg, my executors or administrators, by an instrument in
writing under or their, or one of their hands and seals, should
particularly describe and ascertain the nature of the said Invention, and
in what manuer the same was to be performed and cause the same
to be filed in the Great Seal Patent Office within six calendar months
next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Arthur Rigg, do hereby declare
the nature of my said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by
the following statement thereof, that is to say :-
In Figures 1 and 2 the governor ball A is connected with a frame B
by means of links and levers centred on N, and the frame B balances

page_text: the ball A, so that in any position the whole apparatus is in statical
equilibrium or nearly so. An adjustable spring S presses against B,
tending to force it towards the engine shaft E, while during rotation
centrifugal force developed in A acts in the opposite direction." An
intermediato position such as the one shewn in the Drawing only occurs
when centrifugal force equals the spring's resistance. On the frame B
are inclines C, D, like those in Figure 5, which fit into projections
F and G, clearly seen by the back view of the eccentric in Figure 3. By
this construction any variation in the position of B moves the eccentric
in a lesser degree, and in a direction at or about at right angles to
its own.
In Figure 4 another modification of these arrangements is shown.
Here the governor ball or weight A is attached directly to the frame B,
and balanced by simple counterbalance weights H. The remaining
details correspond closely with those previously described.
Another construction is shewn in Figure 5; no direct counterbalance
is provided, but the weight A and frame B are connected together much
as in Figure 4, and act by inclines C, D, to vary the stroke of an
éccentric. In order to counteract the effect of gravity in those cases
where this system can be applied, a plunger P gives a constant pressure
against the inclines in such a direction, and to such an amount as will
prevent the weight and frame falling. In connection with this plan it
is well to have an air piston or spiral screw, round which the weight
turns as it travels in or out; or some other contrivance to restrain its
too energetic movements.
.
An eccentric ruled by any of these governors is arranged to act on an
expansion valve in preference to a slide valve, and such an expansion
valve works best when moving in equilibrium. As any construction for
this purpose is well understood, to save unnecessary confusion an
ordinary expansion valve is shewn on the Drawing. It moves on the
back of a ported slide valve K, which is driven by its own separate
eccentric, and the expansion valve is constructed in two parts L and M
which may be set at any required distance asunder. The range of
expansion is settled by the variable stroke of the governor's eccentric,
but by altering the lap on the expansion valve it may for example
vary expansion from stroke to stroke, or else from ¼ to ½ stroko
approximately-

page_text: A slide valve intended to work at high pressures is shown in Figures
6, 7, 9, and 8. Here P, Q, is the surface of an ordinary hydraulic slide
valve, and R, S, and T, U, represent enlargements of its surface in the
same plane as shown by Figure 6, or in another but parallel plane as
shewn by Figure 8, and the additional faces may be placed where most
convenient. They are separated from the ordinary surface of the valvo
by channels open to the inlet. This construction must not be confused
with a customary practice of grooving the surface of ordinary .slide
valves. When applying the same system to circular valves, it is con-
venient to make the grooves concentric, but there must be a communi-
cation from them through the back or otherwise with the inlet.
The Drawings are given to shew the general form of governors and
valves made according to my Invention, but I do not restrict myself to
those designs exactly, as many modifications may be adopted in applying
the system to special circumstances.
Having now described my said Invention of "Improvements in
Governors and Slide Valves," and the manner in which the same may
be carried into effect I wish it to be understood that I claim,―
Firstly. The various arrangements of governor described with any
modifications in construction as may be required to adapt them for
practical use.
Secondly. The use of an expansion valve made in two parts with its
lap adjustable while its stroke is variable, the stroke alone being under
the control of a governor.