IMPROVEMENTS IN A METHOD AND MEANS FOR CONVERTING RECIPROCATING MOTION INTO ROTARY MOTION
Year: 1877

page_text: LETTERS PATENT to William Farr Goodwin, of Stelton, in the County of
Middlesex, and State of New Jersey, in the United States of America, for
the Invention of "IMPROVEMENTS IN A METHOD AND MEANS FOR CONVERTING
RECIPROCATING MOTION INTO ROTARY MOTION."
Sealed the 9th May 1878, and dated the 9th November 1877.
COMPLETE SPECIFICATION filed by the said William Farr Goodwin at the
Office of the Commissioners of Patents on the 9th November 1877.
WILLIAM FARR GOODWIN, of Stelton, in the County of Middlesex, and State
of New Jersey, in the United States of America. "IMPROVEMENTS IN A METHOD
AND MEANS FOR CONVERTING RECIPROCATING MOTION INTO ROTARY MOTION."
The object of my Invention is to convert a direct reciprocating motion into a
continuous rotary motion, avoiding dead centres, and preserving a uniform rotation
at all points between the power exerted upon the rotating shaft and the rotation of
said shaft in order to secure a perfect equilibrium of power at all points of rotation.
I also preserve such a relation between the speed of the reciprocating parts as to
secure a longitudinal equilibrium of the shaft, thus avoiding loss of power at the
bearings of such shaft.
To effect these results, and in order to rotate the shaft, I first attach thereto a
screw-threaded disc or helicoid, and use in combination therewith two corresponding
screw-threaded surfaces connected to and moving with a piston or steam cylinder,
the power being applied in line with the axis of rotation.
Second. To secure an equilibrium of power at all points of rotation I employ a
second apparatus similar to the one last aforesaid, whose bearings upon the shaft are
opposite or nearly opposite to the bearings of the first. This result is also accom-
plished by casting the two helicoidal parts in one piece, forming a double-threaded
screw.
Third. To obtain a longitudinal equilibrium of the shaft I so adjust the
reciprocating parts that in their movements to and from each other they,

page_text: threads.
mood we have adopted for laying out the screw
Figure 2 represents the Invention when used in connection with two steam
cylinders, the parts being in section.
Figure 3 is an end view of the screw thread employed in Fig. 2.
Figures 4, 9, 10, 11, and 12 illustrate modifications in the construction shown in
Fig. 2.
Figure 5 is an end view of the screw shown in Figs. 4, 6, and 7.
Figures 6, 7, and
illustrate further modifications having double-threaded screws;
and Figure 13 is an end view of Figure 11.
I will now describe one method for laying out and forming the patterns from which
the screw-thread sections or helicoidal parts are cast, reference being had to Fig. 1
of the Drawings.
If castings for a movement which makes one full revolution of the shaft for each
reciprocation or forward and backward stroke of the piston is required, a cylinder
of wood or other suitable material is provided and turned to the desired dimensions.
This wooden cylinder should be formed of two pieces joined together in such
manner that they may be easily separated after the screw threads are formed, which
forming of threads is effected by turning in a lathe. The cylinder should be
sufficiently long to form a right-hand thread on one end, and a left-hand thread on
the other. After the right and left hand threads are completed the cylinder is
divided and the corresponding right and left hand threads are placed together
opposite to each other so as to form the movement shown in Fig. If it is
desired to form a movement with two threads, producing one revolution of the
shaft for every two reciprocations of the piston, the cylinder from which the patterns
are made should be composed of four pieces joined together in quarters, which, when
the threads are formed, should be separated and rejoined in the manner above
explained, the right and left threads forming the movement shown in Figs.
If a greater number of threads are required than contained in the two movements
above described, the pattern should be made of wood, in the best possible manner,
and a casting of the pieces should be taken in iron and finished upon a compound
shaping machine geared to move any desired distance either way, so that the sharp-
pointed tool will cut directly to or from the centre of rotation of the piece of move-
ment in process of shaping. The piece should be mounted so as to rotate around its
centre, moving at each stroke of the cutter a distance corresponding to that moved
by the cutter, the relative movements of each being such as to finish a given
distance in an equal given number of strokes of the shaper, which strokes serve to
operate the feed simultaneously for both motions. When this movement is used to
convert rotary motion into reciprocating motion, as is the case with the screw move-
ment described and shown in Letters Patent granted to me in Great Britain under
date of November 9, 1877, No. for "Improvements in Mowing Machines," every
thread imparts a reciprocating movement to the vibrating piece, but when employed
to convert reciprocating into rotary motion (as herein described), every thread
requires a reciprocation of the piston of a steam or other reciprocally moving engine
or power, or reciprocally moving part thereof..
It is obvious that in the use of this movement it is necessary that the wearing
surfaces of the screw inclinations should be kept well lubricated to insure utility and
durability. Hence I have so constructed my movement that it shall be surrounded
by an oil-tight casing which receives and contains a quantity of oil sufficient to
keep the working surfaces thoroughly drenched, and to prevent metallic contact of
the screw-thread inclinations. This oil-tight casing affords another great advantage
peculiar to this movement by making it air-tight; the confined air assists the oil in
resisting a metallic contact of the thread surfaces; and, lastly, it excludes all dust,
grit, or other possible obstructions from the working parts..
:

page_text: The method and means herein described and shown in the accompanying
Drawings as applied for converting reciprocating into rotary motion possesses the
many advantages which are peculiar to the principles of the screw, but which are
not found in any other mechanical principles.
First. The power is imparted to the movement in lines parallel to the axis of
rotation of the shaft; is equally distributed upon all parts of the surface of the disc
around the centre or axis of rotation; bears equally and uniformly upon all points
and lines from the centre to the circumference, making a perfectly balanced power
similar to the steam upon the piston of a reciprocating engine, and acts directly
upon the screw plane, rotating the shaft without lateral pressure upon its journal
bearings. On the contrary, all eccentric arrangements (such as cams) and all com-
pound levers (such as cog gears), loose a large per-centage of power from lateral
pressure in the journal bearings.
Second. The power is continuous and equal at all points in the motion, and none
is lost in reversing the directions, whereas the crank generally in use loses a
large amount of power while it is passing through the two quadrants of its circle
which are nearest to or farthest from the engine. Again, with the crank there is no
point at which the power is direct or equal to that exerted at other points, much
power being wasted by pushing and pulling the journals of the shaft against their
bearings, which thus act as friction brakes.
Third. As this construction admits the most direct application of the powers
above mentioned and loses but little by friction it will of course require less fuel or
other prime power to produce a given result, and as a saving of force is a saving of
expense, my new movement is more economical than those now in use for the same
purposes.
And, lastly. The arrangements for applying the principle are extremely simple
and cheap, and easily adapted to a variety of work.
In Figure 2 I have shown the manner in which the reciprocating motion of two
pistons actuated by, steam or other power, and imparting their power to my
improved movement, is converted into the rotary motion of a driving shaft; and in
this Figure A, A, is the bed plate or frame supporting the engines and screw move-
ment; B is the rotating shaft, mounted in suitable bearings in the girts A², A²;
and C is a section of a screw thread secured to shaft B; C1, C2, are corresponding
sections of a screw thread mounted in a shell or cylinder E constructed to slide
freely in or upon the frame A, A; F and G are two steam cylinders, divided by a
partition, which makes two independently acting engines, the piston of engine F
being connected to the casing E of the movement by means of the piston rod f,
while the piston of engine G is connected to the casing D of the movement by'
means of the piston rod g and links g³, 92, and cross head g¹. I is another section of
screw thread, also secured to shaft B; and I', I2, are two corresponding screw threads
mounted in the casing or shell D, which like casing E slides on frame A, A. As the
rotating pieces or discs I and Care both attached to the shaft B the powers of both
engines are united in rotating said shaft.
The parts I and Care attached to the shaft with their corresponding points opposite
or nearly opposite to each other in the manner shown in Fig. 2, in order to balance
the bearing on the shaft, and to enable the engines to assist each other in supporting
regular and continuous motions. This is accomplished by placing one piston G¹ at a
point slightly in the lead, and at full power at the time that the other piston has
finished its stroke and is beginning to reverse its direction. This action is alter-
nated at every revolution of the shaft B. The piston F¹ is represented as having
finished its stroke in the direction indicated by the arrow. The piston G is repre-
sented as being yet in bearing, and although moving in the opposite direction
longitudinally, yet it continues to impart through casing D the same rotary motion
to the shaft B as did the piston F through shell E.
Any approved method for passing steam in and out of the steam cylinder may be
employed, and I confine my description to the novel features in the mechanism
necessary to apply the principle embodied in my new movement.

page_text: Fig. 4 shows a modified construction in which but one steam cylinder is employed,
the steam engine and the movement being arranged to operate together upon the
one shaft B.
The cylinder A¹ may be made by boring through one piece in the
ordinary way, and afterwards fitting a partition H in the centre, and securing the
same by bolts through the casing, as represented in said Figure 4; or it may be made
in two sections joined together upon the partition H, as shown in Fig. 4. The centre
piece F is made the reciprocating part, and is secured from rotation by means of
grooves, into which the tongue or bar is fitted. This bar is fitted to the inside of
the cylinder A' and to partition H, and prevents the piece F2 from rotating, but
permits it to slide back and forth. The double-headed piston is formed of the discs
of the backs of the screw piece F2, which for this purpose is made in two sections
joined together by means of the sleeve F³, which surrounds the shaft B. The piston
heads are packed in the usual manner to prevent the escape of steam, said packing
serving also to prevent oil from entering into the steam spaces of the cylinder.
The piston is operated by the steam entering between the partition H and the
piston head, acting against each piston head and its corresponding side of the
partition alternately, the valves being made to open and close in any approved
manner.
The rotating sections F of the movement are keyed to the shaft in proper relation
to the reciprocating disc to receive the wedging force of said disc in order to cause
the rotation of the sections F and the shaft B.
The diameter of the steam space may be smaller than that of the movement
should any difficulty be experienced from the mixing of the oil with the steam, or
vice versa.
The waste steam escaping around the piston heads will find vent around the shaft
or through a hole made in the top of the cylinder. This construction admits of
placing two or more of the engines upon one shaft for the purpose of uniting their
power and motion in the manner shown in Fig. 2. In this Figure, as in Figs. 6, 7,
and 8, to be described, the arrangement of screw threads is such that two complete
reciprocations in both directions of the piston are required to produce one revolution
of the shaft, converting speed into power with the proportion of two to one.
In Fig. 6 the steam cylinder A. is similar to that in Fig. 2; the rotating discs I
and C are similarly attached to shaft B, but in this Fig. the steam cylinder is placed
between the screw movements, and the latter are enclosed in cylinders A¹, A², similar
to the steam cylinder A.
The end cylinders may be so made as to retain the oil, in which case the means
used to connect the end discs of the movement casing need not be an oil-tight
chamber.
The reciprocating sections F, F1, are each operated by two rods d, d, e, e, one rod
being placed on each side of the shaft. Two rods are used for each to balance the
power. This is a double-threaded movement similar to that shown in Fig. 4.
Fig. 7 shows a means for operating the movement by any ordinary engine. The
outside screw sections F, F, rotate, one end of each casing D, E, being keyed to the
shaft B. The centre pieces I, C, receive motion from the levers L, L', through holes
in the casings D, E, by means of sleeves e, cast with the central piece surrounding
the shaft B. The centre or vibrating sections I and C are secured from rotating by
means of a cross head, the ends of which pivot at o, o¹, in the levers L, L¹, having
their fulcra at points behind the shaft B. The swinging ends of the levers L, L', are
operated by the steam through the rods f, g, which impart motion and power to the
levers L, L, and through the latter to the cross heads, sleeves, and reciprocating
sections of the movement; the wedging influence of the last, acting upon the rotating
sections F, F, serves to convert reciprocating into rotary motion.
The arrangement just described is very simple, and may be readily applied to
and is well adapted for work on a small scale, to operate street cars, for example,
or for hoisting apparatus, and for many uses where the ordinary engine can be
employed.
Figure 8 shows a steam engine in which two reciprocating screw movements are

page_text: used similar to those shown in Fig. 2. The shaft B passes through the cylinder A,
and to it are keyed the centre rotating pieces I and C. This arrangement permits
that the casings D, E, which enclose the movements and carry the sections F, F, may
be used for piston heads. These casings D, E, can be packed at each of their ends
d', d, e, e², by the ordinary spring or other suitable packing. The steam is admitted
through a port a in the middle of the cylinder, and enters between the two piston
heads d, e, forcing them apart and moving them in opposite directions at the same
time. When the strokes in opposite directions are finished, the induction port is
closed, while at that instant the exhaust. port is opened; the same motion of the
same valve closes the other exhaust ports and opens the induction ports, admitting
steam to both ends of the main cylinder A simultaneously against the opposite or
outer ends d, e, of the pistons D, E, to reverse their motion, forcing them towards
each other. The valve being automatically changed, the motion is continued as long
as steam is supplied. The screw sections F, F, within the pistons in their reciproca-
tions cause the rotation of the shaft, as before explained.
Figures 9 and 10 show different views of the last above-described engine, having
their pistons in different positions respectively, and having a screw movement
similar to that shown in Fig. 2. V, V, are lugs sliding in suitable grooves in the
sides of the cylinder, which serve to prevent the piston casing and its reciprocating
parts of the driving movement from rotating.
Fig. 10 also shows at a, b, c, d, means for admitting steam to and exhausting it
from the cylinder A, but any approved valves may be used..
Fig. 11 shows a modification of the engine, as illustrated by Figures 9 and 10,
and has a similar screw movement, and is operated in the same manner, but has
its screw movements outside the steam cylinder, and two independent pistons
attached to the movement casings D, E, by means of sleeves d, e, that pass through
holes in the cylinder heads, said holes being stuffed steam-tight. Steam is admitted
between the pistons and at both ends of the cylinder in the same manner as shown
in Figs. 8 and 10. The outside shell m serves to support the cylinder and the
slide grooves in which the lugs V move and hold the reciprocating parts from
rotating, and may be cast separate from the movement casings D, E, if desired, and
may form with one end the cylinder head, and be bolted to the cylinder, as shown
in said Fig. 11.
Figure 13 is an end view of the outside casing m cast to the cylinder head. The
grooves V', provided to receive the lugs V, are shown, and also the hollow sleeve d,
by which the piston is attached to the movement and the shaft B.
Figure 12 is a modification of the plans above described, in which three of the
screw movements D, D1, D2, are employed upon the same shaft B, and within the
same cylinder A, which latter is open at both ends, and the casings D, D¹, D², of
the movements serve both as piston and cylinder heads. In this arrangement the
steam is admitted between the ends of the centre movement D and each of the end
movements alternately, forcing them asunder. Each end piston, after finishing its
outward stroke, is drawn back by the screw disc on the rotating shaft in time to
receive the steam, which again forces it out. While one end piston is forced out
by the steam the other is drawn in automatically. This arrangement affords a large
steam surface on the pistons in proportion to the diameter of the cylinder, and
steam is admitted at a, b, c.
In none of the plans herein-before described, and shown by the accompanying
Drawings, do I permit steam to come in contact with the rotating screw surface of
the movement. Each movement casing is constructed so as to retain oil upon the
working surfaces, and in all constructions I avoid rotating the packed piston, and
thus avoid resistance from rotary friction.
In order that my improved mechanical movement may be better understood, I
will explain its principles in detail.
First. The screw is a rotary inclined plane as applied to motion, the rotation of
which must be concentric with its axis, and imparts a rectilinear motion in lines
parallel with said axis of rotation from points radiating to and equidistant-there-

page_text: from; and is the only one of the six mechanical powers which in its action bears
.equally and upon all points around and equidistant from its axis at the same time,
and is independent of central supports and lateral bearings. It differs from the
cam in the fact that the latter acts eccentrically in its operation, and bears alike
upon its supports.
A spirally threaded cylinder may be employed as a cam by applying power on
one side of its axis only, or as a screw by passing it through a female threaded
nut, or applying power on opposite sides of its axis at the same time in the manner
herein-before described,
The single-threaded movement, shown in Fig. 2 (in which one half of a revolution
of the shaft is caused by one direct motion of the piston or power applied in lines
parallel with the axis of the shaft, motion in the opposite direction acting upon the
opposite inclined plane completing the revolution), if used singly would be a cam
movement (its bearings being eccentric or one sided).
The pressure of the power acting on one side of the axis of the shaft would cause
lateral pressure upon the journal bearings of the shaft, which would increase
friction in proportion to the power applied.
The end of the thread of a single-threaded screw stops upon one side of its centre
or axis, and only becomes concentric and assumes the principle of a screw when
screwed into a nut or female screw sufficiently to take bearings on the thread all
around its centre, which, with a reciprocating screw movement, would be impossible
with the thread continuing in one direction for the reason that a half turn of a
similar thread winding in the opposite direction must intersect to act in its turn to
continue rotation in one direction; while the reciprocating power is acting in a
reverse direction; therefore, it becomes necessary (in order to complete the con-
tinuous screw principle, and restore the equilibrium and concentricity of the screw)
that a similar arrangement of screw threads be placed on the opposite side of the
shaft, thus making up the other halves of the riglit and left threads, which com-
pletes their circuit around the shaft, see A, B, Fig. 2a. Thus, a bearing is effected
upon both sides of the centre as at A, B, Fig. 2a, at the same time balancing the
power applied, and thus avoiding lateral pressure in the bearings of the shaft.
It is obvious that when two threads are used; as in Figs. 4, 6, 7, & 8, the right
and left threads intersect at four points, viz., the four quarters of the circle; hence
the two ends of the thread are opposite on the shaft, and maintain its con-
centricity, and completes the screw principle in the one system of movement
requiring four direct motions (two in each direction) to complete one revolution of
the shaft.
Having now described my Invention, and the manner and some of the means in
which it may be carried into practical effect, what I claim and desire to secure by
Letters Patent is,-
Firstly. The employment of a right and left hand threaded screw combined into
one movement to convert reciprocating motion into continuous rotary motion, sub-
stantially as set forth.
Secondly. In combination with an engine and a rotating shaft two or more of
the herein-described screw movements arranged to equilibrate the powers exerted
upon the rotating parts, substantially as set forth.
Thirdly. In combination with a steam cylinder and the aforesaid reciprocating.
screw movements, the use of the ends of the oil-retaining cases which enclose the
movements as pistons, substantially as set forth..
Fourthly. In combination with said screw movement a case or box, which serves
to retain oil and supply it to the screw surfaces, substantially as set forth.
Fifthly. In combination with a steam cylinder and the said screw movement,
pistons attached to the screw movements, and arranged to move to and from each
other, substantially as set forth.
Sixthly. In combination with the said movement and a steam cylinder with
open ends, in which the ends of the cases or oil-retaining cylinders which are
attached to and enclose the movements, operate both as piston heads and cylinder
3

page_text: heads, substantially as set forth, and shown by Figure 12 of the accompanying
Sheet of Drawings.
Seventhly. In combination with the said reciprocating screw movement the
lever L, which vibrates the reciprocating part of the movement, substantially as
set forth, and shown in Figure 7 of the accompanying Sheet of Drawings.
In witness whereof, I, the said William Farr Goodwin, have hereunto set my
hand and seal, this Sixteenth day of October, in the year of our Lord One
thousand eight hundred and seventy-seven.
WILLIAM FARR GOODWIN. (L.S.)