IMPROVEMENTS IN APPARATus for Regulating the VELOCITY OF ENGINES WITH GREAT EXACTNESS."
Year: 1880

page_text: LETTERS PATENT to William Wallace Girdwood, of No. 9, Lea Cottages, East
India Dock Rd., Poplar, London, E., in the County of Middlesex, Engineer,
for an Invention of "IMPROVEMENTS IN APPARATus for Regulating the
VELOCITY OF ENGINES WITH GREAT EXACTNESS."
PROVISIONAL SPECIFICATION left by the said William Wallace Girdwood
at the Office of the Commissioners of Patents on the 11th September 1880.
WILLIAM WALLACE GIRDWOOD, of No. 9, Lea Cottages, East India Dock Rd.,
Poplar, London, E., in the County of Middlesex, Engineer. "IMPROVEMENTS
IN APPARATUS FOR REGULATING THE VELOCITY OF ENGINES WITH GREAT
EXACTNESS."
My Invention has for object improvements in apparatus for regulating the
speed of engines with great exactness. The perfections of this machine emanate
from a screw of any pitch or diameter, upon whose axis forces are contending in
opposite directions, which forces when balanced so act upon the screw that steam
is cut off from the main engine thereby; any sudden acceleration of motion is
instantly retarded by the intervention of a fly wheel connected with the screw. The
speed of the engine may be regulated with great nicety by first determing the
amount of force to be balanced through the axis of the screw, upon which is fitted
the driving wheel forming a nut thereto. Now it will be obvious that so long as
motion is uniform and steady that the fly wheel will offer no impediment to be
driven, and inasmuch as the screw is connected with the fly wheel by a crank pin
passing through a hole in the crank attached to the screw, it follows that the fly
wheel and screw always travel at the same velocity; the crank pin is sufficiently
long to allow the reciprocation of the screw. Now the instant the driving wheel
attempts to travel faster than the fly wheel it imparts a rectilinear motion to the
screw from which I derive action for working the steam valves. Now, in order to
make the screw a monitor of specified speeds, it is necessary to apply a series of
forces to the extremity of the screw, either compressive or tensile, opposite that to
which the fly wheel is attached either by weight or spring proportional to the required
velocity. These forces are suspended so long as the increased velocity is constant,

page_text: but on the slightest relaxation of speed they are instantly liberated and return the
screw to its normal position; I also attach to the bed plate of the machine a small
brake which absorbs any momentum that may exist when the screw has reached
the limit of its transit.
The inertness of the fly wheel is a great element in the operation of this machine;
the brake need not be applied only in cases where the engine is liable to be
subjected to very sudden and violent shocks. Upon the driving wheel I fix two stops
which regulate in conjunction with the crank the travel of the screw; I prefer to
connect the screw direct to the throttle valve, but it may be attached to the slide
valve of an auxiliary cylinder for giving motion to the throttle valve; the motions
will be readily understood by reference to the annexed Drawing.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William Wallace Girdwood in the Great Seal Patent Office on
the 10th March 1881.
WILLIAM WALLACE GIRDWOOD, of No. 9, Lea Cottages, East India Dock Rd.,
Poplar, London, E., in the County of Middlesex, Engineer. "IMPROVEMENTS
IN APPARATUS FOR REGULATING THE VELOCITY OF ENGINES WITH GREAT
EXACTNESS."
This Invention has for its object improvements in apparatus for regulating the
speed of engines with great exactness, and so that the speed may be maintained
as uniformly as possible at the desired rate without the engines having increased
its speed before the apparatus can come into action as has hitherto generally been
the case, and so that the act of increasing its speed causes the apparatus immediately
to control and restrain the increase in proportion to the requirements of the case.
The sensitiveness and reliability of this machine arise from the manner in which
the parts are combined to secure the desired action, as will be readily understood
from the following description.
The machine consists of a screw of any suitable or convenient pitch or diameter,
upon whose axis forces are contending in opposite directions, which forces when
balanced so act upon the screw as to cause steam to be cut off from the main
engine thereby. Any acceleration of motion is instantly retarded by the inter-
vention of a fly wheel connected with the screw. The speed of the engine may be
regulated wrth great nicety by first determing the amount of force to be balanced
through the axis of the screw upon which is fitted the driving wheel forming a nut
thereto. Now it will be obvious that so long as the motion is uniform and steady
the fly wheel will offer no impediment to being driven, and inasmuch as the screw
is connected with the fly wheel by a crank pin passing through a hole in the
crank attached to the screw, it follows that the fly wheel and screw always travel
at the same velocity. The crank pin is sufficiently long to allow the reciprocation
of the screw.
I will now proceed, by the aid of the accompanying Sheet of Drawings, to more
particularly describe and explain the machine and its mode of action. Fig. 1 shows
in longitudinal elevation and part section one form and arrangement of the machine
herein before described, the driving pulley D and the fly wheel B being shown in
section.
Fig. 2 shows a transverse view of the machine. A is the screw of any suitable
pitch or diameter, and is connected to the fly wheel B by the crank pin C which is
allowed to work freely in a hole of the same diameter in the crank arm L; motion
is given to the screw by the boss of the driving wheel D which forms a kind of
nut thereto, and this boss or nut revolves in one bearing E. A cylinder F is cast
upon or attached to the face of the driving wheel and serves to envelope or
cover the crank L and stops H, H, in order to preserve or protect these parts from
dust or dirt. J is the brake attached to the bed plate in order to preserve the
inertness of the fly wheel; K is a graduated scale for indicating the speed and
pressure which is actuated by a suitable spring or weight acted upon by the
apparatus. The action of this arrangement is as follows:-
The moment there is any attempt of the driving wheel to move faster than the
fly wheel it imparts a rectilinear motion to the screw which immediately acts on
the parts operating on the steam valves. This screw, by means of a spring or
springs or weight or weights, has a certain graduated resistance applied to its
endlong motion which is proportional to the required velocity, and these resistances
are marked upon the graduated scale so as to represent the velocity and pressure so
long as the velocity is constant; the resistances do not come into action, but on the

page_text: slightest relaxation of speed the resistances instantly cause the screw to return to
its normal position, allowing thereby an increased supply of steam so as to bring
the speed up to its proper point. The small break attached to the bedplate will
come into action on there being any excess of momentum after the screw has
reached the extent of its travel. The inertness of the fly wheel is a great element
in the operation of this machine, and the break is only needed in those cases whero
the engine is liable to meet with very sudden and violent shocks. Upon the driving
wheel I fix two stops which regulate, in conjunction with the crank, the travel of
the screw.
By preference I connect the screw direct to the throttle valve of the
engine by suitable connections, but it may be attached to or connected with the
slide valve of an auxiliary cylinder for giving motion to the throttle valve, and
the annexed Drawings being referred to will render this plain.
'
Having now described the said Invention of machine for regulating the velocity
of engines with great exactness, and the manner in which the same is to or may
be performed or brought into practical use, I desire to state that I do not limit
or confine myself to the precise details shown in the accompanying Sheet of
Drawings, and herein before specified, as the same may be modified without
departing from the nature of the said Invention, nor do I claim any of the parts
individually as new, but what I do claim as of my Invention, and desire to have
protected by Letters Patent is, the arrangement and combination of parts forming
a suitable regulator for the working of steam engines combined together and acting
in the manner and as hereinbefore described and specified, and as illustrated in the
accompanying Sheet of Drawings, or any mere modification thereof.
In witness. whereof, I, the said William Wallace Girdwood, have hereunto set
my hand and seal, this Tenth day of March, in the year-of our Lord. One
thousand eight hundred and eighty one.