Improvements in Toothed or Sprocket Wheels with Variable Pitch, Especially Applicable to Chain Gearing.
Year: 1887

page_text: Date of Application, 6th Dec., 1887
Complete Specification Left, 1st Sept., 1888
Complete Specification Accepted, 5th Oct., 1888
Improvements in Toothed or Sprocket Wheels with Variable Pitch,
Especially Applicable to Chain Gearing.
A communication from abroad by PAUL DE MONICOURT, of 11, Rue Saint Petersbourg,
Paris, in the Republic of France, Engineer.
I, WILLIAM PHILLIPS THOMPSON F.C.S. M.I.M.E. of the Agency for Foreign
Patent Solicitors 6, Lord Street, Liverpool and 6, Bank Street, Manchester both in
the County of Lancaster and 323 High Holborn in the County of Middlesex Civil
Engineer, do hereby declare the nature of this invention to be as follows:-
This invention has for its object, a new kind of toothed wheel, having movable
teeth which are fixed to the rim separately, or in groups or segments, by means of
various fastening devices. The positions of these teeth are capable of being regulated
at will, and by this arrangement it is possible to obtain a wheel with variable pitch,
more especially suitable for chain gearing.
The special object of this is to remedy the disadvantages arising from the wear,
which rapidly takes place in chain gearing, and results in a decreased efficiency of the
same, the said wear being caused by an elongation of the links in the chain, without a
For
corresponding or equivalent elongation of the pitch of the teeth on the wheel.
the purpose of obviating this inconvenience the teeth, instead of being fixed, cast or
forged on, so as to form an integral part of the rim, as is usually the case, are
susceptible of being displaced or altogether removed at will.
These teeth can be separated from each other and fixed on the rim by various
fastening devices, such as a simple nut, nut and check nut screws, keys etcetera ; or
These can be
they can be grouped in movable segments, which are fixed on the rim.
placed on the whole periphery of the rim, or distributed in groups thereon, leaving
intervals without teeth.
In the case where the teeth are separate from each other, it is possible to leave
between each two, a space sufficient to allow of a certain amount of elongation in the

page_text: pitch of the chain, consequent upon the wear thereof. As soon, however, as the pitch
of the chain, whether ordinary link chains, (studded or open) various forms of plate
link chains, Ewart chains, cables provided with sockets or other pieces at regular
intervals, has reached a certain amount of elongation, one tooth can be removed from
the wheel, and the pitch increased by setting the various teeth further apart from each
other by means of wedges placed between them or below them.
As in practice, the wear on a link, from one tooth to the other, is not very appreciable,
and as the pull on the chain at any particular moment, is transmitted only to a small
number of teeth, it is preferable, in order to obtain an easier construction, and a
simpler and more rigid wheel, to group together a certain number of teeth so as to
form segments, whose position on the rim can be adjusted at will by means of nuts
and counter-nuts, or keys; or better still, by adjusting screws.
The arrangement for accomplishing this object may be as follows:
The cast iron wheel is so moulded that the rim is formed with a groove right round
it, in which groups of three or four teeth are placed. These groups or segments are
provided at their extremities with eyes, by means of which their position may be
regulated, and on their inner faces with openings, through which pass the bolts which
(by means of nuts and counter-nuts) secure the segments to the rim.
One segment on the rim is fixed at a definitive point, and all the other segments,
which are movable, are fixed in their required positions by taking this fixed segment
as their origin. In order to permit of the movable segments being adjusted on the
rim, the holes in the latter, through which the retaining bolts pass, are of elongated
form.
The displacement of the segments is effected by means of an adjusting screw, one
end of which is attached thereto by means of a pin passing through the above
mentioned eye, and the said screw.
The adjusting screw passes through a bush with a nut and check nut, the said bush
being provided with trunnions, which pass through the sides of the groove in the same,
and being secured thereto by a nut.
It is obvious that on turning the nuts on the screw by means of a spanner or key,
the segment can, by reason of its connection with the adjusting screw, he displaced on
the rim. Thus all segments save the fixed one, can be shifted on the rim so as to
compensate the wear of the chain links.
This system will be found advantageous in all cases where motion is communicated
by means of chain gear, and more especially for dredgers or excavators where it is
necessary to transmit a great amount of power.
Data th
1097

page_text: Especially Applicable to Chain Gearing.
A communication from abroad by PAUL DE MONICOURT, of 11, Rue St. Petersbourg,
Paris, in the Republic of France, Engineer.
1, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E. of the Agency for Foreign
Patent Solicitors, 6 Lord Street, Liverpool, and 6 Bank Street, Manchester, both in
the County of Lancaster, and 323 High Holborn, in the County of Middlesex, Civil
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 has for its object a new kind of toothed wheel, having movable teeth
which are fixed to the rim separately, or in groups or segments, by means of various
fastening devices. The positions of these teeth are capable of being regulated at will,
and by this arrangement it is possible to obtain a wheel with variable pitch more
especially suitable for chain gearing.
The special object of this invention is to remedy the disadvantages arising from the
wear, which rapidly takes place in chain gearing, and results in a decreased efficiency
of the same, the said wear being caused by an elongation of the links in the chain,
without a corresponding or equivalent elongation of the pitch of the teeth on the
wheel. For the purpose of obviating this inconvenience the teeth, instead of being
fixed, cast, or forged on, so as to form an integral part of the rim. as is usually the
case, are susceptible of being displaced or altogether removed at will.
These teeth can be separated from each other and fixed on the rim by various
fastening devices, such as a simple nut, nut and check nut screws, keys etcetera ; or
These can be
they can be grouped in movable segments, which are fixed on the rim.
placed on the whole periphery of the rim or distributed in groups thereon, leaving
intervals without teeth.
In the case where the teeth are separate from each other, it is possible to leave
between each two, a space sufficient to allow of a certain amount of elongation in the
pitch of the chain, consequent upon the wear thereof. As soon, however, as the pitch
of the chain, whether ordinary link chains, (studded or open) various forms of plate
link chains, Ewart chains, cables provided with sockets or other pieces at regular
intervals, has reached a certain amount of elongation, one tooth can be removed from
the wheel, and the pitch increased by setting the various teeth further apart from each
other by means of wedges placed between them or below them.
As in practice, the wear on a link, from one tooth to the other, is not very
appreciable, and as the pull on the chain at any particular moment is transmitted
only to a small number of teeth, it is preferable, in order to obtain an easier con-
struction, and a simpler and more rigid wheel, to group together a certain number of
teeth, so as to form segments whose position on the rim can be adjusted at will by means
of nuts and counter nuts or keys; or better still by adjusting screws.
In the accompanying drawing, Figure 1 is a sectional elevation of a portion of the
wheel with its inovable tooth segments: Figure 2 a plan: Figure 3 a cross section
through the rim and tooth segment through line x, x of Figure 1: Figure 4 a cross

page_text: section through the rim in front of the adjusting nut along, the line y, y' of
Figure 1.
The cast iron wheel is so moulded that the rim A is formed with a groove B right
round it, in which groups of three or four teeth C, D, etcetera, are placed, these groups
or segments are provided at their extremities with eyes E by means of which their
position may be regulated, and on their inner faces with openings F through which
pass the bolts, which (by means of nuts and counter nuts) secure the segments to
the rim.
On the drawing, one segment C is shown fixed by means of bolts c, and all the
other segments, which are movable like segment. D, are fixed in their required
positions by taking this fixed segment as their origin. In order to permit of the
inovable segments being adjusted on the rim, the holes d in the latter, through which
the retaining bolts pass, are of elongated form. These grooves or holes d would be
made continuous by slightly modifying the construction of the wheel rim.
The displacement of the segments D is effected by means of an adjusting screw G,
one end of which is attached thereto by means of a pin passing through the eyes E.
The adjusting screw passes through a bush L with a nut and check nut H H', the
said bush L being provided with trunnions, which pass through the sides of the groove
in the rim, and being secured thereto by nuts M.
It is obvious that on turning the nuts H H on the screw by means of a spanner or
key, the segment can, by reason of its connection with the adjusting screw G, be
displaced on the rim. Thus all segments, save the fixed one C, can be shifted on the
rim so as to compensate the wear of the chain links.
This system will be found advantageous in all cases where motion is communicated
by means of chain gear, and more especially for dredgers or excavators where it is
necessary to transmit a great amount of power.
The shape of the teeth and the dimensions and proportions of the various parts used
in the constructions of the wheels may be, of course, varied to meet the requirements
of the case.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me by
my foreign correspondent, I declare that what I claim is :
1. The improved toothed or sprocket wheels with variable pitch, which consist of
movable teeth separated from each other in groups or segments; said teeth or
segments being capable of adjustment as regards their distance apart, or suppressed at
will, and fastened on the rim by means of suitable fastenings which permit, owing to
their adjustability, of a wheel being produced which has a variable pitch and is especially
applicable to the transmission of power by means of a chain, substantially as described
and shown.
2. The combination with the herein described improved toothed or sprocket wheel
with movable teeth and variable pitch, of an adjusting screw consisting of an
arrangement of nuts secured to the rim of the wheel, and of a screw connected with
the teeth or movable segments, and which admits of the position of said teeth or
segments being adjusted at will, so that the pitch of the wheel may be increased or
diminished, substantially as and for the purpose described.
3. The arrangement of toothed or sprocket wheels, with movable teeth and variable
pitch, consisting of groups of teeth forming movable segments attached to the rim by
means of bolts and nuts, the position of which can be adjusted at will by means of
adjusting screws, substantially as and for the purpose set forth.
Dated this 30th day of August 1888.
WM. P. THOMPSON & Co.,
Agents for the Applicant.