IMPROVEMENTS IN WORM GEARING APPLICABLE IN AGRICULTURAL AND OTHER MACHINES
Year: 1879

page_text: LETTERS PATENT to John Imray, of No. 20, Southampton Buildings, in the
County of Middlesex, for the Invention of "IMPROVEMENTS IN WORM GEARING
APPLICABLE IN AGRICULTURAL AND OTHER MACHINES." A communication from
abroad by Edouard Maitre, of Montigny-sur-Aube (Cote d'Or), France.
PROVISIONAL SPECIFICATION left by the said John Imray at the Office of
the Commissioners of Patents on the 29th March 1879.
JOHN IMRAY, of No. 20, Southampton Buildings, in the County of Middlesex.
"IMPROVEMENTS IN WORM GEARING APPLICABLE IN AGRICULTURAL AND OTHER
MACHINES." [A communication from abroad by Edouard Maitre, of Montigny-sur-
Aube (Cote d'Or), France.]
This Invention relates to improvements in worm gearing of the kind described in
a Specification filed by me on the 19th July 1878, No. 2890, a communication to
me from abroad by Edouard Maitre, and in the means of applying such gearing in
agricultural machines, such as reaping or mowing machines, in which a wheel
revolving comparatively slowly has to impart much more rapid movement to a
crank or eccentric for driving knives or cutters. The gearing, according to this
The wheel
Invention, consists essentially of two parts, the wheel and the worm.
has, projecting radially from its periphery or projecting from its face parallel to its
axis, a number of pins equally spaced round the circumference, on each of which
pins is mounted a roller capable of turning freely. These rollers take the place of
the ordinary cogs or teeth of a worm wheel, gearing with the worm, but with a
rolling action instead of a rubbing friction, so that the wheel can readily turn the
worm, or the worm can turn the wheel without the frictional strain and the
excessive wear of ordinary worm gearing. The worm, when it gears with rollers
projecting perpendicularly from the face of the wheel, is cylindrical in form, mounted
with its axis parallel to the face of the wheel, so as to have several of the rollers
engaged in its successive convolutions. It is generally preferable, however, to
mount the rollers of the wheel projecting radially from its periphery, and in that
case the worm has an outline hollowed in the middle so as to fit the circular arc of
the wheel against which it lies, several of the rollers being also in this case engaged
with the successive convolutions of the worm. In both cases the convolutions of
the worm require a peculiar formation so as to suit the uniform movement of the

page_text: rollers in their circular path. Hence, on each side of the middle line of the pitch,
or that radius of the wheel which is perpendicular to the axis of the worm, the
screw pitch of the worm has to be somewhat less than the pitch at the middle, that
is to say, the pitch instead of being uniform throughout the worm has to become
gradually lessened in each direction from the middle in the proportion of the sines
of circular arcs to the arcs themselves. In order to produce a screw of this kind,
the worm is mounted in a latho to have its screw thread cut, but instead of that
thread being cut by a tool travelling in a straight line parallel to the axis, which
would cut a uniform thread in the usual way, the cutting tool is fixed on a radius
equal to that of the wheel with which the worm is intended to gear, and is made
to move uniformly in the circular arc determined by this radius, while the worm
itself is uniformly revolving round its own axis. The general or average pitch of
the worm thus prepared will obviously be determined by the relative speed of the
two movements, and the worm so cut will, when applied to the wheel, fit by its
successive convolutions the rollers of the wheel as they advance to their successive
positions in their circular path. In applying gearing of the kind described to
agricultural machines, such, for example, as a reaping machine, the wheel is fixed
on the axle of the travelling wheels of the machine, revolving comparatively slowly.
The worm is mounted in bearings in a bracket, with its axis a little inclined from
the vertical. On the lower end of its axis is fixed a disc, which has a crank pin
connected by a jointed connecting rod to the bar which works the knives or cutters
of the machine. The worm being put in comparatively rapid motion, the knives or
cutters are caused to reciprocate quickly, as required in such machines, without the
necessity for complex intermediate gearing. At the upper and lower bearings of
the worm spindle, oil cups are provided for lubrication, and the upper bearing may
conveniently be arranged as a centre pin, fixed in the bracket projecting down into
an oil cup formed in the upper end of the worm. The jointing of the connecting
rod to the crank at the lower end of the worm spindle consists of a block having
bushes fitting the crank pin, retained in their place by gib headed or T headed
bolts, and through this block passes a transverse pin, on which the connecting rod
is jointed, the whole thus forming a double joint admitting of the movement of the
connecting rod in two planes. The worm gearing above described may obviously
be applied in machines of other kinds in which it is desired to convert rotary
motion in one plane into a rotary motion in a plano at right angles to the former
with considerable change of speed.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Imray in the Great Seal Patent Office on the 18th July
1879.
JOHN IMRAY, of No. 20, Southampton Buildings, in the County of Middlesex.
"IMPROVEMENTS IN WORM GEARING APPLICABLE IN AGRICULTURAL AND OTHER
MACHINES." A communication from abroad by Edouard Maitre, of Montigny-sur-
Aube (Cote d'Or), France.
This Invention relates to improvements in worm gearing of the kind described
in the Specificacion filed by me on the 19th July 1878, No. 2890, a communication
to me from abroad by Edouard Maitre, and in the means of applying such gearing
in agricultural machines, such as reaping or mowing machines, in which a wheel
revolving comparatively slowly has to impart much more rapid movement to a
crank or eccentric for driving knives or cutters. The gearing according to this
Invention consists essentially of two parts, the wheel and the worm. The wheel
has projecting radially from its periphery or projecting from its face parallel to its
axis a number of pins equally spaced round the circumference, on each of which
pins is mounted a roller capable of turning freely, these rollers take the place of
the ordinary cogs or teeth of a worm wheel gearing with the worm, but with a
rolling action instead of a rubbing friction, so that the wheel can readily turn the
worm, or the worm can turn the wheel without the frictional strain, and the
excessive wear of ordinary worm gearing. The worm when it gears with rollers
projecting perpendicularly from the face of the wheel is cylindrical in form, mounted
with its axis parallel to the face of the wheel, so as to have several of the rollers
engaged in its successive convolutions. It is generally preferable, however, to
mount the rollers of the wheel projecting radially from its periphery, and in that
case the worm has an outline hollowed in the middle so as to fit the circular arc of
the wheel against which it lies, soveral of the rollers being also in this case engaged
with the successive convolutions of the worm. In both cases the convolutions of
the worm require a peculiar formation so as to suit the uniform movement of the
rollers in their circular path, hence, on each side of the middle line of the pitch, or
that radius of the wheel which is perpendicular to the axis of the worm, the screw
pitch of the worm has to be somewhat less than the pitch at the middle, that is to
cay, the pitch instead of being uniform throughout the worm, has to become
gradually lessened in each direction from the middle, in the proportion of the sines
of the circular arcs to the arcs themselves. In order to produce a screw of this
kind, the worm is mounted in a lathe to have its screw thread cut, but instead of
that thread being cut by a tool travelling in a straight line parallel to the axis
which would cut a uniform thread in the usual way, the cutting tool is fixed on a
radius equal to that of the wheel with which the worm is intended to gear, and is
made to move uniformly in the circular arc determined by this radius, while the
worm itself is uniformly revolving round its own axis. The general or average
pitch of the worm thus prepared will obviously be determined by the relative speed
of the two movements, and the worm so cut will, when applied to the wheel, fit by
its successive convolutions the rollers of the wheel as they advance to their successive
positions in their circular path. In applying gearing of the kind described to
agricultural machines, such for example as a reaping machine, the wheel is fixed on
the axle of the travelling wheels of the machine revolving comparatively slowly.
The worm is mounted in bearings in a bracket with its axis a little inclined from
the vertical. On the lower end of its axis is fixed a disc which has a crank pin
connected by a jointed connecting rod to the bar which works the knives or cutters
of the machine. The worm being put in comparatively rapid motion, the knives or
cutters are caused to reciprocate quickly as required in such machines, without the
necessity for complex intermediate gearing. At the upper and lower bearings of the

page_text: worm spindle, oil cups are provided for lubrication, and the upper bearing may
conveniently be arranged as a centre pin fixed in the bracket projecting down into
an oil cup forined in the upper end of the worm. The jointing of the connecting
rod to the crank at the lower end of the worm spindle consists of a block having
bushes filling the crank pin retained in their place by gib-headed or T headed bolts,
and through this block passes a transverse pin on which the connecting rod is
jointed, the whole thus forming a double joint, admitting of the movement of the
connecting rod in two planes. The worm gearing above described may obviously
be applied in machines of other kinds in which it is desired to convert rotary
motion in one plane into a rotary motion in a plane at right angles to the former
with considerable change of speed.
In the accompanying Drawings are shewn portions of a reaping machine to
which is applied worm gearing according to this Invention. Fig. 1 is an end view,
Fig. 2 a plan, and Fig. 3 is a vertical section through the worm. A is the rectan-
gular frame carrying bearings B for the axle C of the travelling wheels R. On the
axle C is fixed the worm wheel D, having on its periphery rollers which engage
with several convolutions of the worm E. A section of the worm is shewn to an
enlarged scale at Fig. 4. Its lower spindle O turns in a bearing in the bracket F,
and it is centered at the top by an adjusting pin o¹ entering an oil cup n¹. The
lower spindle O works in an oil cup n, and carries a disc G with a crank pin a,
which by means of the connecting rod X works the cutters S. The head to which
the connecting rod is jointed is shewn in transverse section in Fig. 4, and in sectional
plan at Fig. 5; its bush and key being shown at Fig. 7, and the end of the con-
necting rod being shewn in section at Fig. 6. The head has within it a bush b held
in position by a key c, and it is jointed to the connecting rod end e by a bolt d
passed through holes o in the head and in e, the end of the connecting rod h works
in a sleeve g, which is jointed toe by a pin f, the two joints d and permitting
movement to the connecting rod in two planes. To allow a little elastic yielding of
the rod, there are springs or caoutchouc washers r, r', placed in the sleeve g on each
side of a collar h² on the rod h. The lower end of the connecting rod h is shewn in
section at Fig. 8, and in plan at Fig. 9. It terminates with a pin i working in a
socket j, which is connected by a horizontal joint k to the bracket that projects
upwards from a flange m fixed to the bar of the cutters S. It will be seen that all
the working parts described are provided with means of lubricating them, the oil
cups n and n¹ for the bearings of the worm, the oil cavity X in the head of the a
connecting rod, and also the oil cavity and passages in ; and i at the lower end of
the connecting rod. The raising or lowering of the cutters S is effected by a chain
t attached to the connecting rod at x, and passing over a guide pulley u to a volute
or fusee pulley 8', of which a plan and front view are shewn to an enlarged scale in
Figs. 11 and 12 respectively. This fusee is fixed on the axis q of a worm wheel p, 4
which is worked by a worm v. A lever L serves to cant the cutter frame to an
angle. Figs. 10 to 14 are transverse sections of the cutter fingers N on the lines
A, B, and E, F, of Fig. 13, which is a longitudinal section of these fingers slotted to
receive the cutters and cutter-bar M to which the cutters are fixed by bolts y.
Figs. 15 and 16 shew, by side view, and plan, and arrangement for raising the 4
cutters. The cutter frame is jointed at o¹ to a lever b' which is pivoted at o³, and
on the same pivot is the segment 83, the periphery of which receives the chain x'
that passes over the guide pulley p'. On pulling this chain, the whole is raised
till the lever b¹ comes against a stop 2, whereupon the farther pulling of the chain
cants the segment &³, causing the cutter frame S to rise as indicated by the arrow. 5
The travelling wheels R are connected to the axle C by clutches shewn in section
and face view at Figs. 17 and 18. The nave of the wheel contains a number of
spring sliding pawls 2 which engage in recesses of the boss d, which is filled by
a feather c¹ on the axle C, and can be slid up to clutch with the pawls t. The
bosses d' may be connected so as to be slid up to a clutch or slid back to unclutch 5
simultaneously, as shewn on the diagram plan, Fig. 19. Each boss is worked by a
fork lever m¹ pivotted at e¹ for the one boss, and m³ pivotted at e² for the other

page_text: boss, the two levers being connected by a rod 6%, so that on moving the lever m³
both bosses are slid into or out of gear with the wheel naves.
The lever m² may
be made as shewn to an enlarged scale at Fig. 20, with an inclined slot near its
end, so that on working a vertical lever passing through this slot, the lever m³ is
moved to the one hand or the other horizontally.
Although the above description relates to the application of the improved worm
gear to work the cutters of a reaping or mowing machine, it may likewise be
applied to work the rake or gathering apparatus, as well as to other machinery.
Sometimes it is convenient to transmit power by a rapidly rotating shaft driven by
the worm gear, as shewn diagrammetrically at Fig. 21, for working a threshing
machine. is the vertical horse shaft revolving slowly by means of a wheel R
and worm H; it drives rapidly the communicating shaft M, the end A of which
has a worm wheel R2 working a worm H' on the beater shaft X. Fig. 22 shews
diagrammatically the variation of pitch of the worm referred to above, as resulting
from the engagement of several of its convolutions, with rollers of the worm wheel
on each side of the centre line. It will be understood that the pitch a is greatest
at the middle, and decreases each way from the middle, 6 being less than a, and c
being less than b, as will result from the process above described for cutting or
rendering true the screw for this purpose.
Having thus described the nature of this Invention, and in what manner the
same is to be performed as communicated to me from abroad by my foreign
correspondent, I claim,―
First. The construction substantially as herein described of a worm wheel with
rollers for teeth, and of worm having its pitch suitably varied to engage several of
the said rollers in several of its successive convolutions.
Second. The method herein described of cutting or rendering true & worm, such
as is referred to in the preceding claim, by the use of a cutting tool travelling in a
circular path whilst the worm revolves on its own axis.
Third. The combination of a roller, wheel, and worm of the kind referred to in
the first claim, with a double jointed connecting rod for working cutters of a
reaping or mowing machino, substantially as herein described.
Fourth. In the arrangement referred to in the preceding claim providing for
lubrication of the worm bearings by means of oil cups enclosing them as herein
described with reference to Fig. 4 of the accompanying Drawings.
In witness whereof, I, the said John Imray, have hereunto set my hand
and seal, this Eighteenth day of July, in the year of our Lord One thousand
eight hundred and seventy nine.
JOHN IMRAY. (LS)