IMPROVEMENTS IN REGULATORS OF SPEED OR POWER, APPLICABLE PARTLY TO ENGINES, AND PARTLY TO OTHER MACHINERY.
Year: 1872

page_text: LETTERS PATENT to Arthur Rigg, Engineer, of St. Benèt Chambers,
Number One, Fenchurch Street, in the City of London, for the In-
vention of "IMPROVEMENTS IN REGULATORS OF SPEED OR POWER, APPLICABLE
PARTLY TO ENGINES, AND PARTLY TO OTHER MACHINERY.
Sealed the 7th March 1873, and dated the 16th December 1872.
PROVISIONAL SPECIFICATION left by the said Arthur Rigg at the
Office of the Commissioners of Patents, with his Petition, on
the 16th December 1872.
"
I, ARTHUR RIGG, Engineer, of St. Benèt Chambers, Number One,
Fenchurch Street, in the City of London, do hereby declare the nature
of the said Invention for "IMPROVEMENTS IN REGULATORS OF SPEED OR Power,
APPLICABLE PARTLY TO ENGINES, AND PARTLY TO OTHER MACHINERY,” to he as
follows:-
The first part of this Invention comprises arrangements for changing
the stroke or position, or stroke and position, of eccentrics, cranks, or
cams acting on the valves of steam or other elastic fluid engines, so as

page_text: to vary the quantity admitted and act as a governor of speed. When
applied to hydraulic or inelastic fluid engines similar arrangements act
upon their main cranks for the same purpose.
One arrangement for doing this consists of a compound screw, having
at one end a thread of the usual kind, and at the other end a long
pitched screw, constructed so that rotation is produced by drawing a nut.
along it. This compound screw is held in bearings perpendicularly upon
Attached to the above-named nut, or
the engine shaft, or nearly so.
connected with it, is a weight capable of being moved by the action of
centrifugal force, and held towards the engine shaft by a spring. When
sufficient number of revolutions are attained by the engine, so that enough
centrifugal force is generated in the weight to overcome the resistance
of the spring and friction, a motion of the weight ensues, thereby
When speed
causing a corresponding rotation of the compound screw.
is reduced the weight is drawn back again by the spring and the screw
reversed. By means of a nut upon the other portion of the compound
screw, or other suitable connection, the position or stroke of eccentrics
or cams on the main shaft may be varied, so as to act on the engine
valves and diminish or increase the quantity of steam admitted, and so
regulate speed.
Either one weight and spring may be employed, as above-described, or
more than one, as most convenient
•
A similar arrangement applies to the main cranks of hydraulic engines
to alter the piston stroke, so performing the part of a governor to
regulate the quantity of water or other inelastic fluid admitted, and the
same construction used with pumps driven by cranks or excentrics would
vary their stroke as the speed of rotation is changed.
Another construction of apparatus for carrying out these objects
replaces the compound screw by a flat plate having in it an oblique
groove. This plate is drawn in and out by centrifugal force acting on a
weight and spring similarly to the nut before described. A stud upon
the excentric or cam, whose position has to be changed, fits into the
oblique groove which acts after the manner of inclined planes, and
draws the excentric backwards and forwards in a direction at right
The same effect
angles to the movement of the weight, or nearly so.
would be produced by allowing a stud to be drawn by the weight and
fixing a plate to the excentric. Both these arrangements may be further

page_text: modified by allowing the plate to oscillate on a stud, the groove being
oblique relatively to the path of the weight, whether that path be straight
or curved.
The second part of this Invention applies to hydraulic engines or other
machinery where the load is subject to isochronous variations. Upon
the main shaft is a cam having a roller or slide held against it by a
known pressure. At one period of a revolution the cam experiences
resistance from this pressure, and at another period the pressure assists
its rotation. These periods are calculated so as to compensate for
irregular strains due to the action of a crank or other cause.
Either part of this Invention may be used with or without the other.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Arthur Rigg in the Great Seal Patent Office on
the 27th May 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, Arthur
RIGG, Engineer, of St. Benet Chambers, Number One, Fenchurch Street,
in the City of London, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Sixteenth day of December, in the year of our
Lord One thousand eight hundred and seventy-two, in the thirty-sixth 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 executors, 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 thereafter 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 "REGULATORS OF SPEED OR POWER, APPLICABLE
PARTLY TO ENGINES, AND PARTLY TO OTHER MACHINERY," upon the condition
(amongst others) that I, the said Arthur Rigg, my executors or admi- .
nistrators, by an instrument in writing under my, or their, or one of
their hands and seals, should particularly describe and ascertain the
nature of the said Invention, and in what manner the same was to

page_text: be performed, and cause the same to be filed in the Great Scal 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 5
be performed, to be particularly described and ascertained in and by
the following statement, reference being had to the Drawings annexed,
and to the letters and figures marked thereon, that is to say :-
―:
Figures 1 to 10 refer to the first part of this Invention for using the
centrifugal force of a revolving weight to alter the positions of excentrics 1
or cams in steam or other elastic fluid engines, that they may act on the
valves and cut off steam sooner or later and so regulate speed. When
applied to hydraulic or to inelastic fluid engines somewhat similar
arrangements are used to alter the stroke of the main cranks.
Figures 11 to 14 refer to the second part of this Invention for 1
equalizing the load on machines or giving an uniform or nearly uniform
driving power to hydraulic or inelastic fluid engines where as usually
constructed the tangential driving power would be irregular. Similar
letters correspond, as far as possible, to similar parts in the different
arrangements shewn by the Drawings.
2
Figures 1, 2, 3, and 4 are views of one form of construction, Figures
5 and 6 represent another, Figures 7 and 8 are a third design, and
Figures 9 and 10 are a more compact method of carrying out the same
idea. They all represent the method by which the centrifugal force of
the weight W, resisted by a spring S, acts upon excentrics working slide a
valves or expansion valves of steam engines, so varying the cut off steam
and regulating speed as governors.
Similar arrangements may be used to act on cams, but the first
arrangement (Figures 1 to 4) is preferable for use in regulating the
stroke of the main cranks of hydraulic or inelastic fluid engines.
In all the Figures referring to the first part of this Invention A is a
casting keyed on the engine shaft E or other shaft connected therewith.
This casting carries an excentric C in a slide so arranged that it can move
backwards or forwards radially for expansion valves where the stroke
only requires alteration, but tangentially to a small circle where a single
short D slide valve is used to vary the expansion of steam. The latter

page_text: plan is shewn only on Figures 5 and 6. The excentrics on all the other
figures are for working expansion valves that move on the back of slide
valves, cutting off more or less steam by variation in stroke only, and it
is desirable that these valves shall be balanced and cut off steam by their
inner edges in a manner well known to engineers.
°
The weight W may be made in one or more pieces if desired, and it is
fixed upon a fork F, which slides radially with it under control of the
adjustable spring S. When the number of revolutions is such that
centrifugal force in this weight overcomes the spring, it flies out, and
whenever speed, diminishes the spring recovers its original position,
drawing back the weight, and finally retaining it at such an intermediate
position that both forces, namely, that of the spring and the centrifugal
force of the weight, balance each other. This feature is common to all
the arrangements included in the first part of my Invention, and by
varying either weight or spring, any given number of rotations may
cause motion. Moreover, the weight may be constructed to travel its
full range by slight variation in speed, so giving a motion practically
isochronous, or by the use of a spring of different proportions, a much
greater change in speed may be requisite to give the full range, and thus
a sluggish governor action be secured.
The excentric C is put on in halves, and slides in a groove on the
block A to the extent of its required range, and it is moved by a
compound screw K, M. The nut G is attached to C, and the nut H to A,
one having a right and the other a left hand thread. Thus one rotation of
the screw K, M, gives a movement to the excentric equal to the pitch of
both these screws added together. Upon the weight W there is fixed a
third nut J, having a long thread, so that rotation is given to K, M, by
any movement of W. By this arrangement an excentric can be made to
vary its position or stroke or both in proportion to the movement of a
weight, and by working a slide or expansion valve through such arrange-
ment a direct acting governor is obtained. One important and essential
feature is contained in all these arrangements of the first part of my
Invention, namely, that though any movement of the weight W effects
an alteration in the eccentric, yet no movement of the eccentric bas
power to alter the position of W.
The above description refers mainly to Figures 1, 2, 3, and 4, and so
far as general principles are concerned applies to the Figures up to No. 10
inclusive. In all a weight, by the effect of centrifugal force during

page_text: rotation, draws a spring and regulates the position of excentrics, and for
the double acting compound screws simpler arrangements may be
substituted.
Figures 5 and 6 shew a governor acting directly on a slide valve eccentric
by means of an oblique groove N, O, in the fork F, and a pin O in the
excentric itself. The motion of this excentric is not radial to the shaft,
but tangential to a small circle, and while shortening its stroke the angle
of advance beyond the crank is increased, and the lead kept right. In
this case no further expansion valve is required, though the plan shewn
by Figures 5 and 6 may be adapted to vary the stroke of an expansion
valve just as the plans in the other Figures may be adapted to work
changes in the position and stroke of slide valve excentrics.
Figures 7 and 8 shew a lever P, Q, O, replacing the previously
described arrangements for transferring motion from the weight W to
the excentric C. In this case there is a stud R fixed in the main ]
casting A, upon which the lever can oscillate. There is a short slot in one
end, which receives a pin O connected with the excentric C, and a long
slot in the other end to admit a pin Q attached to W, and to allow of its
motion. As the weight slides radially the lever P, Q, O, is constructed
to oscillate upon its stud R, and so move the excentric C in the slide
prepared for it, and thus the apparatus becomes a governor of speed, as
previously described.
Figures 9 and 10 illustrate an arrangement of governor acting on the
same general principles as those already described, but differing in some
details. The weight W is fastened upon a flat plate F, F, oscillating
upon a stud O in the main casting A, which forms a circular guard
enclosing the whole apparatus. An adjustable flat spring S presses
against a pin H in the plate F, F, and controls any movements of W as
its position varies through the action of centrifugal force. In the
plate F, F, there is a curved groove R, P, through which passes a pin P,
attached to the excentric C. This excentric is free to slide radially, as
shewn when working an expansion valve, but tangentially to a small
circle when working a slide valve direct. By any oscillation of the
plate F, F, upon its centre O the curved groove draws the pin P in or
out, and so varies the position of the excentric in a manner corresponding
with the movements of W, thus cutting off more steam as the speed of
the engine increases.

page_text: Figures 11 and 12 illustrate the second part of my Invention for
equalizing the strain in driving machinery, such as a double acting lift
and force pump, where the load is subject to periodic variations; and
Figures 13 and 14 shew the inverse, namely, where the power is
uniformly irregular, in the case of an hydraulic engine with a single
cylinder, and yet the tangential driving power of the shaft is the same
or nearly the same at every part of its revolution.
In Figures 11 and 12 the shaft A turns a crank B, giving motion
through a connecting rod F to the plunger C. Under ordinary circum-
stances strain is increased as the crank approaches the middle of its
stroke, and diminished towards the ends, but to compensate for these
variations a double ended cam D, D, is keyed on the shaft (and also
forms the crank face plate in the present illustration), and against it a
roller E is permanently pressed by. a suitable weight W at the end of a
lever G, H. The cam D, D, lifts the weight twice in every revolution at
those periods where the driving power required by the pump is less than
an average, and the weight in falling. again turns the crank over during
those periods in a revolution where the driving power required would be
greater than an average.
By apparatus constructed upon this principle, whether the auxiliary
power be obtained by gravity or other methods irregular strains may be
rendered nearly or altogether uniform provided they occur at regular
periods.
Figures 13 and 14 are elevations partly in section shewing an hydraulic
engine with my Invention applied, for rendering its irregular driving
power uniform or nearly so. It consists of one oscillating cylinder K,
having a piston area equal to twice that of the ram G. While the
engine is working high pressure water is admitted permanently on the
upper side of the piston, but alternately with the exhaust on the lower
side by means of a valve. Thus motion is got in the usual manner, and
transmitted to the shaft A, causing a tangential driving power, which
varies from zero to a maximum twice in every revolution. In order to
take away the excess over an average during those parts where the power
is strongest, and restore it where the power is weakest, the cam D is
keyed on the main shaft A, with a roller E held against it by hydraulic
pressure through a supplementary plunger F, also permanently in con-
nection with the inlet. This cam D is formed so that it shall force F

page_text: down when the tangential pressure on A would be above the average,
and that the cam D shall itself be turned over by the reaction of F when
the tangential pressure on A would be found below an average. By these
arrangements an uniform driving power is obtained, notwithstanding the
intermittent action of an ordinary crank.
When preferred the pressure given by a small plunger F may be
obtained by other means.
It may be mentioned that the shape of cam D is shewn correct for
an oscillating cylinder such as K, but would not necessarily be the same
for other oscillating cylinders, nor for hydraulic engines worked with
connecting rods and fixed cylinders.
Having now described the nature of the said Invention, and the
manner in which it may be performed, I do not confine the same to the
precise details of parts so long as the general principles are maintained,
nor do I restrict myself to carrying out the first and second parts together
or separately, but as may be found most convenient. What I do claim as
Invention is,-
my
Firstly. The construction of governors or regulators of speed or power,
described and as illustrated by the Drawings in Figures 1 to 10.
Secondly. The cam arrangement described and illustrated by Drawings
Figures 11 to 14, for equalizing the strain on shafting where the load is
subject to periodic variations through the action of cranks or other
causes, or else for equalizing the tangential driving power of hydraulic
engines where the crank usually causes irregularities.
In witness whereof, I, the said Arthur Rigg, have hereunto set
my
hand and seal, this 27th day of May, in the year of our Lord
One thousand eight hundred and seventy-three.