Year: 1899

page_text: Date of Application (in United Kingdom), 24th Oct., 1899
Complete Specification Left, 2nd Mar., 1900-Accepted, 12th May, 1900
I, CHARLES TUCKFIELD, of Albany, Western Australia, Engineer, do hereby
declare the nature of this invention to be as follows:-
This engine is designed for use as a single, compound, triple, or quadruple
expansion engine, for steam, liquid air, gas, oil or any other suitable motive
Huid.
I cast a cylinder leaving one end solid (on this end is bolted the cylinder
cover which forms steam chest): through this end a hole is bored for the piston
rod to reciprocate and revolve in, also a straight through port for front end
of cylinder. Another port is cast partly through the solid end with a steam
passage communicating with the back end of cylinder; there is also a circular
groove with communication to exhaust pipe. This end is faced up and on it
rotates a circular slide valve through which there is a steam passage which
registers with steam ports. The other part of the valve has a recess which over-
laps the steam port and exhaust groove. This valve is caused to revolve by
means of a feather projecting from a long keyway in the piston rod, the rod
itself passes through valve and is revolved by the end projecting from cylinder
being keyed on to a roller which has one or more endless spiral grooves cut in it,
each groove engaging with a stud, said stud being firmly fixed to bed plate so
that when the piston is pushed, these grooves pressing against the studs causes
the roller to revolve carrying piston and valves around with it: this rotatory
movement is communicated to the machinery to be worked by the end of the
driven shaft sliding into guide passage in roller, this passage being constructed
of such shape that the reciprocatory motion of the roller does not affect it, whilst
the rotatory movements carries it round.
For the purpose of reversing a channel is cut in that portion of the slide valve
in which the feather works and a sleeve is fixed to the valve passing out of the
cylinder through the stuffing box. By means of this sleeve the valve can be
carried round until the feather engages with the other end of the channel this
reverses the direction of the steam.
In compound or triple expansion engines the steam chest of the lower pressure
cylinders forms the back cover of the higher pressure cylinders.
Dated this 24th of 1000
HASELTINE; LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.

page_text: I, CHARLES TUCKFIELD, of 4, Thames View, East Molesey, in the County of
Surrey, formerly of Albany, Western Australia, Engineer, do hereby declare the
nature of this invention and in what manner the same is to be-performed to be
particularly described and ascertained in and by the following statement:-
This invention relates to a rotary engine of the kind in which the reciprocating
motion of a piston is converted into rotary motion by means of a helical cam.
Hitherto such engines have been constructed with a helical cam groove formed
on the interior of the cylinder and an abutment on the piston engaging there-
with, and this arrangement has been modified by forming the cam groove upon
the piston itself or upon an extension of it, and the abutment upon the cylinder.
Both these arrangements however have proved to be unsatisfactory; in the former
case a great leakage of steam took place from one side of the piston to the
other, and in the latter case a large and cumbrous engine resulted from the
necessity of providing a piston itself equal in length to the length of the stroke,
the cylinder being thus at least twice the length of the stroke. In another
modification which has been proposed a hollow drum was employed stationary
outside the cylinder and an abutment fixed on the piston rod engaged with a
helical groove formed on the interior surface of the hollow drum, the driven
member being connected to the abutment by means of a sliding connection.
Further disadvantages arose in all these constructions and were caused by the
difficulty in obtaining access to the mechanism for converting the reciprocating
motion of the piston into rotary motion; moreover the cost of constructing such
engines was greatly in excess of that of the usual type of engines of similar horse-
power.
According to the present invention these disadvantages are overcome by the
employment of a reciprocating helical cam external to the cylinders which is
operatively connected to the piston and which engages with a stationary abut-
ment. The cam which may have a cylindric body or drum has formed upon it
an endless helical thread which for half a turn is right-handed and for the other
is left-handed, or the thread may consist of zigzags of such helices, further the
right and left hand helices may be duplicated, or if desired opposed in the man-
ner hereinafter described. The cam is connected to a driven member by means
of a coupling which permits endwise, but prevents rotary motion of these parts
relatively to each other; the preferred form of coupling comprises two or more
driving rods not co-axial with either the driving part or the part driven and
which slide in the connected parts.
An engine constructed according to this invention may be arranged as a com-
pound engine the cylinders being in this case preferably arranged in tandem and
having a valve chest formed between and constituted by the ends of adjacent pairs
of cylinders.
The valves may be of the rotary type carried upon a continuous piston rod and
operated thereby directly.
The piston rod is preferably longitudinally grooved and extends through the
valve a tongue is situated within the groove and engages with the valve. A
piece of metal or other suitable material of similar cross-section to the groove is
also situated therein so as to occupy that portion of the groove which at any
time is in the stuffing box through which the rod passes. This piece of metal or
the like, hereinafter referred to as a filler, may or may not be formed in one

page_text: piece with the tongue connecting the valve and the piston rod. The object of the
filler is to prevent the escape of steam through the groove in the piston rod as
the latter reciprocates through the stuffing box; rotary but not endwise motion
takes place between the filler and stuffing box.
Reversing may be effected by forming stops upon the valves to limit the
angular movement of valve and piston rod in relation to each other and providing
gear for manually giving such limited movement to one of the valves.
The cam abutment and coupling between the cam and driven member may
conveniently be arranged within an oil bath.
The pistons may be either rotatively or non-rotatively connected to the piston
rod and in the latter case will act as fly-wheels inasmuch as the piston rod
rotates with the cam.
The employment of a cam external to the cylinder enables the latter to be of
the usual size and construction while the formation of an endless helical groove
on. the exterior of a cylindric cam or drum is both easier and cheaper than if it
were on the interior of a hollow drum. Moreover it is easy to rigidly connect
the cam or drum with the piston rod, and the reciprocating cam can be made
of large radius as to enable a short and rigid abutment to be used the com-
bination of large cam and short abutment conducing to easy working.
In the accompanying drawings:-
Figure 1 is a longitudinal central section partly in elevation of a compound
engine constructed according to this invention,
Figure 2 is an elevation of one of the valves employed in Figure 1 with the
part by which it is actuated;
Figure 3 is a section on the line 3-3 of Figure 2,
Figure 4 is a section on the line 44 of Figure 1,
Figure 5 is an elevation indicating The nature of two modified forms of the
helical cam shown in Figure 1;
Figure 6 is an elevation of another modified form of cam.
Like letters indicate like parts throughout the accompanying drawings.
Upon a base A cylinders B are arranged, preferably in tandem. Each cylinder
is provided with a piston C secured either rotatively or non-rotatively to a con-
tinuous piston-rod D. Valve chests E are arranged between, and constituted by,
the ends of each adjacent pair of cylinders B, the valve chest of one of the
said cylinders being formed upon its free end.
The piston-rod D passes out of the group of cylinders at one end and has fixed
upon it, external to these cylinders, a cam F: an endless helical groove F1 is
formed upon the exterior periphery of the cam F, the groove F1 being right-
handed for half a turn and left-handed for the other half, or being composed of
a zig-zag of such helices, as shown in Figure 6. An abutment G preferably
having upon it one or more rollers to engage the groove F¹ is secured to the
base A.
A driven member H is arranged as a continuation of the piston rod D and is
connected to the cam F by means of a coupling K which comprises two or more
driving rods K¹. These driving rods are not co-axial with either of the con-
nected parts and are fixed to the driven member H and slide in recesses formed
in the cam F. Obviously the driving rods K¹ may be fixed to the cam F and
slide in recesses on the driven member H or one or more rods may be fixed to
each of the connected parts and a corresponding number of recesses made in
each.
Angular co-axial sliding connections when used to transmit rotary motion have
been found liable to jam; the advantage of the construction described above is
that the driving rods K¹ being some distance from the axis of the connected
parts are exposed to less stress and are therefore less likely to wear or to jam. This
liability to jam may be further reduced to a minimum by making the driving
rods K circular in cross-section.

page_text: An oil bath L may be arranged to contain the cam F, abutment G and
coupling K, the piston-rod D and driven member H passing in through stuffing
Doxes L' and being supported by bearings L³.
The valves M are in the shape of discs and are mounted upon the piston-rod 1)
within the valve chests E bearing against the end of their respective cylinders.
They are provided with a slot and a recess M2, the slot M being adapted to
register alternately with two admission ports B' B2, formed in the end of the
cylinders against which the valves bear, as the latter rotate. A circular groove B³
(Figure 4) concentric with the cylinder is formed upon this end of each cylinder
. and communicates with the exhaust. The recess M2 of the valve M is arranged
so as to put one of the admission ports B₁ B2 into communication with the
groove B and so to the exhaust, while steam is being admitted through the
slot M and the other port.
The valves derive their rotary motion from the piston-rod 1 by means of a
tongue I engaging with a longitudinal groove D² in the latter and with stops Ma
formed upon the valves M; these stops are so arranged as to permit a limited
angular motion of the valves in relation to the piston-rod 1. It is necessary for
the rotary but not the reciprocating motion of the piston-rod D) to be com-
municated to the valves and in order to permit of the relative reciprocating
motion of the valves and piston-rod the groove D in the latter for each valve is
made of a length at least equal to the length of stroke.
Stuffing boxes 0 are formed on those ends of the cylinders B which are not
provided with valves and the piston-rod D passes out through the stuffing boxes.
In order to prevent the escape of steam through the groove D2 in the piston-
rod as the latter reciprocates through the stuffing boxes (), a filler P is pro-
vided for the groove D2, and is arranged within the stuffing boxes O, means
being provided to ensure each filler P remaining within its stuffing box 0.
The filler P may be made in one with or connected with the tongue DI engag
ing the piston-rod and valve, or it may be be made separate and flanged at each
end of its stuffing box.
Means are provided for manually operating one of the valves through the
limited distance allowed by the stops M³ this is preferably effected by providing
a sleeve M upon the valve M which is situated at one end of the group of
cylinders, this sleeve passing. out through the valve chest E containing its valve
and through a stuffing box Q formed upon the said valve chest. A filler P
.similar to those already described with reference to the stuffing boxes O is
situated within the stuffing box Q to prevent the escape of steam between the
sleeve and the groove D2 in the piston rod 1).
The operation of an engine constructed as above described is as follows:-
As the pistons C reciprocate within their cylinder the cam F will also recipro-
cate this reciprocating motion will be converted into rotary motion by means of
the abutment G engaging with the helical groove F¹ upon the cam F, and this
rotary motion will be communicated to the driven member H by means of the
coupling K. The reciprocating motion of the cam F will however not be com-
municated to the driven member H owing to the fact that the driving rods K'
are adapted to slide within recesses formed in one or both of these members.
The piston rod D will have both rotary and reciprocating motion and its rotary
notion will be communicated to the valves M by means of the tongue D'
engaging with both the groove D2 and with one of the stops M3 formed upon the
valves M; thus as the valves M rotate steam will be admitted alternately to each
end of the cylinders B through the ports B1 and B2. It wil be seen that the
exhaust from the high pressure cyinder is led into the valve chest of the inter-
mediate cylinder by way of the recess M2 in the valve M and circular groove B³
on the face of this cylinder which communicates with the steam chest of the
intermediate cylinder.. Similarly the exhaust from the intermediate is led into
the valve chest of the low pressure cylinder.

page_text: If desired two or more endless helical threads or grooves may be formed upon
the cam ; it is preferred that the two endless helices should be opposed to one
another, as shown in full lines in Figure 5, and in this case there will be two
abutments G, each engaging with one of the helices and arranged at opposite
ends of a diameter of the cam. If desired, however, two or more parallel helices
may be employed as shown in dotted lines in Figure 5. Again a zig-zag of
helices may be employed as shown in Figure 6, and there may be two or more
series of sucli zigzags which may be opposed to one another.
By employing opposed helices the simultaneous thrusts set up on them by
their respective abutments and operating on opposite sides of the cam act to
relieve the bearings of unbalanced stress such as would come upon them in the
case of single or parallel helices.
As stated above the pistons C may be either rotatively or non-rotatively con-
nected to the piston-rod D, in the former case they would act as fly-wheels.
Reversal of the engine is effected by moving the valves and piston rod in rela-
tion to each other through the range permitted by the stops, in a manner
analogous to that in which reversal is effected in an engine fitted with the well-
known arrangement of loose eccentric.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed 1 declare that what
I claim is: -
1. In a rotary motor of the kind described the combination of a reciprocating
helical cam external to the cylinder and a stationary abutment engaging it with
or without an oil bath.
2. In a rotary motor of the kind described the combination with one or more
cylinders of a reciprocating helical cam external to the cylinder and a stationary
abutment engaging it with or without an oil bath.
3. In a rotary motor of the kind described the combination with a reciprocat-
ing helical cam external to the cylinder of a stationary abutment engaging it
and a coupling between the cam and the part driven which permits endwise but
prevents rotary motion of those parts relatively to each other.
4. In a rotary motor having a reciprocating piston rod a helical cam with more
than one endless helix substantially as described.
5. In a rotary motor having a reciprocating piston rod a helical cam with
opposing helices for the purpose described.
6. In a rotary motor the combination with tandem cylinders of a valve chest
constituted by the ends of adjacent cylinders and a rotary valve therein.
7. In a rotary motor the combination with a reciprocating and rotating piston
rod of a rotary valve operated directly by the piston rod with or without
for permitting a limited angular movement of the valve in relation to the rod
for the purpose of reversing and with or without gear for imparting to it that
limited movement.
8. In a rotary motor of the kind described the combination with a reciprocat-
ing helical cam of a coupling which permits endwise but prevents rotary motion
in relation to each other of the cam and the part driven and includes two or
more driving rods not co-axial with the connected parts substantially as described.
9. In a rotary motor of the kind described the combination with a reciprocat-
ing helical cam external to the cylinder of a piston rod and a piston all three
rigidly connected so as to turn together for the purpose described.
10. In a rotary motor the combination with a reciprocating and rotating piston
rod of a piston free to rotate thereon but reciprocating with the rod.
11. In a rotary motor the combination with a rotary valve of a grooved piston
rod extending through it, a tongue engaging the valve and that groove and a
filler for a portion of the length of the groove substantially as described and
illustrated in the accompanying drawings.
1

page_text: 12. In a rotary motor the combination with a reciprocating rotating piston rod
of a rotary valve and means for rotating that valve and for adjusting its angular
position from the exterior of the valve chest, substantially as described and
illustrated in the accompanying drawings.
13. The complete rotary motor substantially as described or illustrated in the
accompanying drawings.
Tad 1 14 1
1000
CHARLES TUCKFIELD.
Boult, Wade & Kilburn,
Agents for the Applicant.