Improvements in Toothed Gearing for the Transmission of Power.
Year: 1889

page_text: Date of Application, 12th Apr., 1889
Complete Specification Left, 11th Oct., 1889-Accepted, 16th Nov., 1889
PROVISIONAL SPECIFICATION.
Improvements in Toothed Gearing for the Transmission of Power.
I, ALFRED JAMES JARMAN, of 82 Kellett Road, Brixton, in the county of Surrey
Electrical Engineer do hereby declare the nature of this invention to be as
follows:
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The object of my invention is to construct toothed wheels for the transmission of
power in such a
manner that a comparatively noiseless motion is obtained, the
wear and tear is reduced, fractured or damaged cogs are easily replaced, "back-
lash" a frequent source of accident is minimised, and a perfect rolling contact is
maintained these advantages rendering the improved gearing according to my
invention applicable to the transmission of power from any source, and for any
purpose where toothed gearing is admissible.
The type of geared wheels generally known as "mortise" wheels have been
devised and employed chiefly for the attainment of noiseless running, and because
of the facility afforded by the special construction thereof for the removal of cogs,
and renewal of same when desirable. Wood has hitherto been adopted as the material
of which such cogs are made, and the general design of such mortise wheels has
been carried out so as to place the whole strain of transmission upon the bearing
surfaces of the teeth or cogs; these being individually supported by the shank
alone, fitting within a recess in the rim of the wheel, and secured by a pin under-
neath said rim. The defects of this arrangement are in that in the first place,
wood, such as hornbeam, apple, and the like, is sonorous, and merely semi-elastic,
therefore the "stroke" attending the contact of each cog with the corresponding
cog upon the other member of the train of gearing, is transmitted throughout
the solid portions of the machinery however rigid these may be, in a series of
vibrations. In the second place, the support afforded by the shank of the cog
within the recess formed in the rim of the wheel, alone, is insufficient, when the
force applied to each cog in the transmission of power is taken into account. And
a further disadvantage in the employment of this system of gearing is in that
the contact at the pitch line or circle is upon the surface of the cogs, therefore
the back lash due to clearance is apparent whenever the load or speed is varied,
or the motion is entirely stopped, and also, the wheels are frequently placed too
deeply into gear, so that the pitch circles intersect, or the reverse, entailing great
loss of power by friction in either case, and increasing the wear and tear of
the cogs.
I prefer to employ what is known as vulcanized fibre as a suitable material or
substance for the formation of the teeth or cogs of wheels for the transmission of
power, and the use of said material forms an important feature of this invention,
by which I am enabled to eliminate the disadvantages attending the use of gearing
as hitherto constructed and employed, and hereinbefore enumerated.
In carrying my invention into effect I form upon, or attach to, the rim of a mortise
wheel, two cheeks or flanges, upon both sides of said rim, and preferable of such
diameter as to extend to, or beyond, the intended pitch line or circle of the wheel, so
that, in fact the peripheries of said cheeks or flanges constitute a rolling or frictional
contact with the corresponding cheeks or flanges of the other wheel or wheels, either
at the pitch circle, or upon either side of the same. The teeth or cogs are formed,
preferably, of vulcanized fibre, although in certain cases I may employ cogs or teeth
made of other material or substance. Said cogs are fitted, and driven into the
recesses formed within the rim of the wheel for that purpose, but, instead of, pinning
the shank upon the inside of the rim as hitherto has been the case in the construction
of mortise wheels, I prefer to drill a hole through both cheeks or flanges, just below,

page_text: or upon the pitch line or circle, and fit a pin, screw, or bolt and nut thereto, which
passing through both flanges as aforesaid, and also through the cog, firmly secures
the latter to the wheel. By the adoption of this device according to my invention I
am enabled to transmit the strain imposed upon the cog by the working load, directly
to the rim of the wheel, from the centre of said cog, instead of the root thereof as
hitherto, and the shank is thereby relieved of the major part of the strain, and the
wheel is structurally rendered more efficient. I may form the rim of said wheel with
one of the flanges or cheeks cast upon it, or rigidly attached thereto, and the opposite
flange or cheek may be detachable in order to afford greater facility for "pitching"
and "trimming" the cogs than would be the case were both flanges immoveable.
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The opposite wheel of a pair according to my invention need not necessarily be a
mortise wheel, but may be made entirely of metal, being, however provided with
cheeks or flanges corresponding to those upon the other wheel, and of such diameter
as to be in close contact therewith when the wheels are properly in gear, so that the
pitch lines or circles coincide. When this is the case, the circumferential velocity of
the peripheries of the cheeks or flanges in contact is proportional to that of the rolling
contact of the cogs of the wheels, therefore the action of said cheeks or flanges is that
of a pair of friction drums or wheels, assisting the cogs or teeth in the transmission
of power, and also reducing the reverse impulse known as "back lash," when the load
is varied.
I may however cause the flanges or cheeks to extend to the points of the teeth or
cogs, in which case I form vertical grooves upon both inner surfaces, to aid in
supporting said teeth or cogs, these being pinned exactly upon the pitch line, as
herein before described.
I do not confine myself to the employment of any special kind, or formation of
cogs or teeth in carrying out my invention, although I prefer to use those of cycloidal
form.
Dated this 11th day of April 1889.
FREDK. WALKER & HYDE,
4, Little Moorfields, London, E.C., Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Toothed Gearing for the Transmission of Power.
I, ALFRED JAMES JARMAN of 82 Kellett Road, Brixton, in the County of Surrey,
Electrical 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 :-
The object of my invention is to construct toothed wheels for the transmission of
power in such a manner that a comparatively noiseless motion is obtained, the wear
and tear of the working parts is reduced, fractured or damaged cogs are easily
replaced, and "back-lash," which is a frequent source of accident is minimised, while
a. perfect rolling contact is maintained. A further advantage resulting from the
reduction of vibration while working, is that the spindles or shafts used for trans-
mitting power are not so liable to fracture, due to crystallization, or fatigue of metal,
as occurs in the case of ordinary toothed gearing, as hitherto made and used.
The improved gearing, according to my invention is applicable to the transmission
of power from any source, and for any purpose where toothed gearing may advan-
tageously be employed.
The type of geared wheels generally known as "mortise wheels" have been devised
and used chiefly for the attainment of noiseless running, also for the facility afforded
by the special construction thereof for the removal and renewal of cogs when
desirable. Wood has hitherto been adopted as the material best suited for making the
cogs, and the general design of such mortise wheels bas been carried out so as to
place the whole strain of transmission upon the bearing or driving surfaces of said
cogs, these being individually supported by the shank alone, fitting within a recess in

page_text: the rim of the wheel, and secured by a pin passing through that portion of said shank
which projects below said rim. The defects of this arrangement are in that, in the
first place, wood, such as hornbeam, apple, and the like is sonorous, and merely semi-
elastic; therefore the stroke attending the contact of each tooth or cog with the
corresponding cog upon the other member of the train of gearing, is transmitted by a
series of vibrations throughout the solid portions of the machinery, however rigid
these may be. In the second place the support afforded by the shank of each cog
within the recess formed in the rim of the wheel, alone, is insufficient when the force
applied to, and strain imposed upon each cog in the transmission of power is taken
into account. And a further disadvantage in the employment of this system of
gearing is in that the contact at the pitch line or circle is upon the surface of the
cogs only, therefore the "back lash," or recoil due to the clearance, is apparent when-
ever the load or speed is varied, or the motion is entirely stopped, and also, that the
wheels are frequently placed too deeply into gear, so that the pitch circles intersect,
or the reverse, entailing great loss of power by friction in either case, and increasing
the wear and tear of the teeth or cogs.
I prefer to employ what is known as vulcanized fibre as a suitable material or
substance for the formation of the teeth or cogs of geared wheels for the transmission
of power, and the use of said material forms an important feature of this invention by
means of which I am enabled to eliminate the disadvantages attending the use of
gearing as hitherto constructed and employed, and hereinbefore enumerated.
In order that my invention may be clearly understood, I have appended the accom-
panying sheet of drawings, in which Figure 1 represents a portion of a mortise wheel
and pinion in gear, in elevation, with a portion of the flange of said mortise wheel
removed to shew the manner in which the cogs or teeth are fitted. Figure 2 is a
cross sectional view of the same upon the line A B and Figure 3 is an end elevation
of the portions of said wheels as shewn in front elevation by Figure 1. Figure 4 is a
front elevation of a portion of a mortise wheel and pinion shewing an alternative
arrangement, and Figure 5 is a cross section upon the lines CD, Figure 4. Figure 6
is another view representing a cross section upon the line E F Figure 4, and also
illustrating a further modification. Figures 7 and 8 are front and end elevations
respectively of one of the cogs or teeth formed according to my invention, and
Figures 9 and 10 shew a portion of one of the flanges, in elevation and plan respec-
tively, shewing the recesses for holding and retaining the cogs or teeth in place.
Similar letters of reference indicate corresponding or equivalent parts throughout the
several views.
In carrying my invention into effect I may form a mortise wheel A, Figures 12
and 3 in such a manner as to have two flanges R, R' cast upon the rim or body
thereof, or otherwise attached thereto, and the peripheries of said flanges are truly
turned to co-incide with the face of the teeth or cogs when fitted and trimmed. The
rim or body of the mortise wheel A is provided with rectangular holes for the
reception of the shanks of said cogs, and the flanges R R are each furnished with
a recess or groove opposite to said rectangular holes, said groove or recess being
either rectangular or of other suitable shape. This is best shown by the detached
views Figures 9 and 10, the recesses or grooves being shewn by g. If said recesses g
be rectangular, the cogs or teeth, Figures 7 and 8 may be so shaped as to have
similarly formed edges, f and f¹ so as to fit tightly therein when driven into their places,
and are thus retained, the shank s fitting into the hole in the rim of the wheel in the
usual manner. I drill, or otherwise pierce a hole through each tooth or cog, and also
through each flange R R¹ at or near to the pitch line or circle, and pass a pin a
through said hole, either rivetting or burring the ends over, or employing a suitable
bolt or nut. In this method of construction I am enabled to cause the total strain
upon each cog or tooth in the transmission of power, to be immediately transferred
to the rim and arms of the wheel from a point at or near the pitch line or circle, the
recesses g Figures 9 and 10, and the projections or rims ff¹ fitting therein, Figures 7
and 8, taking part of said strain, and the pin or bolt a sustaining the remainder of
said strain due to the load. I form the pinion B, which may be a cast, or solid wheel,

page_text: with flanges T T², corresponding to those upon the mortise wheel R R¹, and truly
turned to coincide therewith when the wheels A and B are properly in gear. There-
fore, in the case illustrated by Figures 1, 2, and 3, the flanges T, T₁ upon the pinion B
extend above the root of the tooth or cog to the extent of the clearance, as shown by
the dotted circle. The flanges R R and TT' therefore act in the same manner as
friction discs or drums, and since the circumferential speeds thereof are exactly pro-
portional to the relative speeds of the geared wheels, it is evident that. the action of
said flanges not only renders the motion uniform, but also in a great measure prevents
"back lash," and also keeps the wheels properly in gear so that the pitch lines or
circles thereof perfectly coincide.
Therefore, by the adoption of my invention, the elasticity of the cogs or teeth con-
structed of vulcanized fibre, which is also a bad conductor of sound waves, or
vibrations, renders the wheels noiseless when running, and is at the same time a more
durable material for the purpose than wood, as hitherto used; and the manner of
forming the wheel, and fitting said teeth or cogs therein causes the strain to be borne
by the larger and working part thereof, and relieving the shank in consequence; also
the frictional or rolling contact of the peripheries of the flanges causes the motion of
said wheels to be uniform.
As a modification of my said invention, I may cause said flanges R R¹T T¹ to
extend to, or near to, the pitch line or circle, as shewn by Figures 4, 5 and 6, fitting
the teeth or cogs in the same manner as hereinbefore described, with the exception of
the position of the bolt or pin a which may be either above or below the pitch line or
circle, according to the extent of the flanges R R¹. One of said flanges may be cast
or formed upon the rim of the wheel as shewn by R, Figure 5, while the opposite
flange R is removeable, and fixed to said rim by bolts, studs, or equivalent means,
preferably however being kept in position by a fillet d.
Or, as an alternative device, I may cause both flanges to be separate from the
body of the wheel, as shown by Figure 6, which is a cross section upon the line E F
Figure 4. In this case I may employ through bolts e for holding said flanges in
position in addition to the fillets d d¹, or I may adopt any suitable means for
attaching them to the rim of the wheel Á.
In any of the foregoing modifications, I do not confine myself to the rectangular
recess 9 Figures 9 and 10, but may form these to correspond to the shape of the
cogs or teeth, so that the rims or edges f, f', Figures 7 and 8, may be dispensed with,
and the cogs may preserve the same conformation and outline throughout the
width thereof, which in certain cases may afford greater facility for pitching and
trimming. I may also form the recess g Figures 9 and 10 of such a shape and
dimension as to engage with a fillet formed upon the cog or tooth, of a width
equal to, or less than, the width of the point of said tooth or cog, thus saving
the waste of material incidental to the cutting of blanks to the width of the roots
of said teeth or cogs. In the case however of the modification shewn by Figure 5,
where the flange R is removeable and R¹ is cast upon, or otherwise formed upon
the wheel A, I prefer to form or shape the recesses in the flange R¹ in the
manner shewn by Figures 9 and 10, or I may form these recesses to suit a narrower
projecting fillet as hereinbefore described, which is less than the width of the cog
or tooth at the pitch line or circle. In either case, the blank may be properly
shanked, fitted, and pitched and trimmed in the usual manner, while the flange R
is removed, the recesses g in R corresponding to the external conformation of the
cogs or teeth, or to the projections formed thereupon.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what I
claim is,
First. In toothed gearing, the construction of a mortise wheel with cheeks or
flanges, in combination with cogs or teeth of vulcanized fibre, retained in position
by pins, bolts and nuts or the like passing through said cogs at or near the pitch
line or circle substantially as herein described, and shewn by the drawings.

page_text: Second. In toothed gearing the employment of fixed or removeable flanges or
cheeks, recessed to fit the sides of the cogs or teeth, substantially as herein described
and shewn by the drawings.
Third. In toothed gearing the employment of flanges or cheeks as referred to in
the preceding claim, arranged so that the peripheries thereof upon the driving and
driven wheels of a train of gearing, may touch when running, and act as auxiliary
frictional driving gear, substantially as and for the purposes herein described, with
reference to the accompanying drawings.
Fourth. In toothed gearing, the employment of one removeable flange, as referred
to in the preceding claim, in combination with a similar flange formed upon the
rim of a mortise wheel, substantially as herein described, and shewn by the appended
drawings.
Fifth. In toothed gearing, the employment of two removeable flanges, or two fixed
ones, as referred to in the preceding claim, in combination with a mortise wheel,
substantially as herein described and shewn by the drawings.
Sixth. In toothed gearing, the employment of what is generally known as vul-
canized fibre for constructing the cogs or teeth, substantially as and for the
purposes herein set forth.
1
1000
FREDK. WALKER & HYDE,
4, Little Moorfields, London, E.C., Agents for the Applicant.