Improvements in Chain Gearing.
Year: 1891

page_text: Date of Application, 13th Mar., 1891
Complete Specification Left, 12th Dec., 1891-Accepted. 16th Jan. 1892
PROVISIONAL SPECIFICATION.
Improvements in Chain Gearing.
I, HANS RENOLD of Green Lane, Manchester in the County of Lancaster,
Engineer, do hereby declare the nature of this invention to be as follows:-
trans-
My invention relates to the chain gearing used in the transmission of rotury
motion as is well understood.
In such gearing the teeth of wheels enter the
spaces between ends of the inner links and the sides of the outer links in
the chain the motion being transmitted from the wheel to the chain or from
the chain to the wheel by the contact of the said teeth with the ends of the
inner links of the chain. In ordinary practice the pitch of the toothed wheel is
made or intended to be the same as the pitch of the chain the supposition being
that the force will be, transmitted through several teeth at the same time so
that the strain and friction will be divided amongst a number of teeth. Even
if this result could be obtained by the employment of great accuracy in the
construction of the parts it would be of short duration as it is well known that
the extension of the chain arising from the wearing of its joints commences as
soon as the chain is put to work and I have found that practically the entire
strain upon a wheel is borne by the teeth singly in succession and is only
divided to some extent between two teeth during the changing of the strain
from one tooth to another. During such changing there is sliding contact
between the parts of the chain and wheel through which the strain is
mitted the result being a loss of power and an excessive wearing of the
parts. Owing to the pitch of the chain being greater than that of the wheel
the strain is taken by the first tooth of a driver wheel which meets the chain the
consequence being that there is only a comparatively loose contact between
the wheel and the part of the chain which is passing over the wheel. To
remedy these defects I so form the block or inner link or links of the chain
and the teeth of the wheels as that on the passing of each successive tooth into
and out of gear the movement of the block or link upon such tooth becomes a
rocking or rolling motion instead of a sliding movement as in the cases of ordinary
gearing, and I make the pitch of the teeth of the driver wheel greater than that of
the chain. Taking the case of a chain composed of metal blocks or extra thick links
hinged together by means of joint pins and outside links I form the block with a
corner at each end of the side which is intended to bed upon the wheel and I adapt
the wheel to take hold of or to bear against the corners upon the blocks.
illustration I will state that each block might be square at each end instead of
semi-cylindrical as is usual so that the block would have four corners. I do not
however confine myself to any precise formation of the block ends so long as
the block has two or four corners more or less acute or it may be slightly
rounded. A form of block which I now consider to be suitable would have four
Hat sides and two ends inclined or curved in both directions from a centre line
to corners on the two sides which would be intended to come into contact with
the peripheries of the wheels. The wheels would be polygonal having teeth at
the junctions of the angles the junctions of the teeth with the flat faces forming
angular corners. The wheels would be so proportioned as that when one tooth
of the wheel and one block of the chain would be in driving contact the next
tooth and block would clear to an extent which would be fixed upon as being
a suitable allowance for extension of the chain during its continuance in use.
addition to this allowance there would be such a clearance for the other end of
the block as would be necessary according to the number of blocks which would
be in contact with the wheel at one time. When the parts are so proportioned
' '
As an
In

page_text: the tooth which is leaving the chain in the case of the driver wheel takes the
strain so that the links which are in contact with the flat faces on the wheel
sustain the pull or driving strain and are therefore pressed into frictional contact
with the wheel and by such contact relieve the teeth from a portion of the strain.
When a block in the chain is leaving the wheel it rolls upon the tooth the
block by such rolling movement permitting the next tooth to take the strain.
I may so form the parts as that the block eud clears the tooth the block rocking
upon its corner without the rolling contact with the teeth. The said block may
in some cases consist of a number of associated links as is usual in some patterns
of chain. If considered to be advisable for any reason the driving contact
might be made with the outer links instead of with the intermediate link which
would take the place of the said block. My invention is applicable in cases
wherein links are so formed as to hinge together without the intervention of
connecting blocks or links.
Dated this 12th day of March 1891.
DUTTON & FULTON,
1, St. James' Square, Manchester, Agents.
COMPLETE SPECIFICATION.
Improvements in Chain Gearing.
I HANS RENOLD of Green Lane, Manchester, in the County of Lancaster,
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 and accompanying drawings :―
My invention relates to the chain gearing used in the transmission of rotary
motion as is well understood. In such gearing the teeth of wheels enter the
spaces between the ends of the inner links and the sides of the outer links in
the chain the motion being transmitted from the wheel to the chain or from the
chain to the wheel by the contact of the said teeth with the ends of the inner
links of the chain. In ordinary practice the pitch of the toothed wheel is made
or intended to be the same as the pitch of the chain the supposition being that
the force will be transmitted through several teeth at the same time so that the
strain and friction will be divided amongst a number of teeth. Even if this
result could be obtained by the employment of great accuracy in the construc-
tion of the parts it would be of short duration as it is well known that the
extension of the chain arising from the wearing of its joints commences as soon
as the chain is put to work and I have found that practically the entire strain
upon a wheel is borne by the teeth singly in succession and is only divided to
some extent between two teeth during the changing of the strain from one
tooth to another. During such changing there is sliding contact between the
parts of the chain and wheel through which the strain is transmitted the result
being a loss of power and an excessive wearing of the parts. Owing to the
pitch of the chain being greater than that of the wheel the strain is taken by.
the first tooth of a driver wheel which meets the chain the consequence being
that there is only a comparatively loose contact between the wheel and the
part of the chain which is passing over the wheel. To remedy these defects I
in the first place make the pitch of the driver wheel greater than that of the
chain and in the second place I so form the block or inner link or links of
the chain and the teeth of the wheels as that on the passing of each successive
tooth into and out of gear the movement of the block or link upon such tooth
becomes a rocking or rolling motion instead of a sliding movement as in the
cases of ordinary gearing.
In order that the nature and intention of my invention may be clearly under-
stood I will describe the same with reference to the accompanying drawings and

page_text: for the same reason I will first refer to the ordinary practice which is illustrated
by Figs. 1 and 2 in Sheet 1.
Fig. 1 represents an ordinary pitch wheel the chain being indicated by a and
the links by straight lines the ordinary links being left out for sake of
clearness. For the purpose of illustration the circles a may represent rollers.
In this fig. the chain is represented as being of exactly the same pitch as the
wheel th rollers a all accurately fitting the sector shaped bottoms of the recesses
between the teeth so that the driving strain would be imparted by say half of
the whole number of the teeth of the wheel. This would be the case so long
as the pitch of the chain would be exactly the same as that of the wheel but
as hereinbefore mentioned the pitch of the chain is constantly lengthening all
the time that the chain is in use. I would remark that by the term pitch I
mean the distances between the centres marked by the asterisks in Fig. 1.
Fig. 2 represents the result of the wearing of the chain. In this example the
pitch of the chain has lengthened considerably as would be the case when a chain
had become very much worn. It will be seen that only one tooth c has a
driving hold upon one of the rollers of the chain the other rollers being
successively forced out of contact with the driving sides of the teeth and with
the bottoms of the recesses as the wheel revolves as indicated in the cases of
the rollers a³ a¹ a³.
It will be clearly apparent that the driving strain is sustained by the tooth c
and that when the next tooth d commences to take the strain the roller a* will
be forced outward and away from the tooth c and will roll up the back of the
tooth ¹. This "riding" of the chain is attended with considerable friction and
loss of power and often with rattling or "hammering" and jerking of the chain
and these evils are increased if the chain be even moderately tight on the slack
side.
"
Figs. 3 and 4 illustrate a wheel and chain constructed in accordance with my
invention. In this example the chain is of shorter pitch than the wheel. My
intention is that the pitch of the wheel shall be longer than the pitch of the chain
to the full extent of the allowance for extension of the pitch of the chain during its
entire " "life so that when through wear the pitch of the chain has become equal to
that of the wheel the chain should be renewed. In the drawings Fig. 3 represents
the chain as when new and Fig. 4 as when considerably worn. In both figs. the
roller A which is just about to leave the wheel takes the thrust of the tooth e so
that the driving power is apparently transmitted through one tooth as in the case
of Fig. 2 but there is this important difference in favour of my improved gearing
that the rollers B C D E and F are forced into tight contact with the bottoms of
the recesses by the strain put upon the chain so that the strain upon the tooth e is
relieved to some extent by the driving contact of the wheel with the said rollers.
It is necessary to make the spaces between the teeth wider than in the case of
Fig. 1. On examining Fig. 3 it will be seen that the clearance between the roller C
and the tooth e' is double the clearance between the parts B and e¹. To enable the
rollers to move back I make the bottom of each recess concentric with the axis of
the wheel. It will be seen that the clearance or freedom for the rollers to move
back between the teeth of a wheel having ten teeth as in the example must be not
less than five times the difference between the pitches of the wheel and the chain.
More clearance would be required in a wheel having more than ten teeth but by
making the clearance sufficient for the largest wheel in a series all the wheels in
such series although varying in diameter and number of teeth may have the same
amount of clearance. The proportions of the parts in Fig. 3 are such as that when
the chain is new the incoming roller G will just clear the back of the tooth.
the chain has extended with use the incoming roller will clear the tooth to a greater
extent as seen in Fig. 4. The extension of the chain might continue until the pitch
of the chain would be the same as that of the wheel when I should consider that
the chain should be renewed. But even if continued in use the rollers would not
ride up the backs of the teeth as in Fig. 2 because of the large clearance between
After

page_text: the teeth. It will be seen that before the tooth e' can take a driving hold upon the
roller B such roller must move back into contact with the driving face of the said
tooth. To enable this to be done without shock I form the driving face of each
tooth of such a curve as that the departing roller A shall when rolling down the
face of the driving tooth e gradually let back the chain until the next roller and
tooth are in contact. Fig. 7 in Sheet 4 illustrates this action. In this example the
dotted line indicates the line of the slack chain just before the roller 2
commences to pass out of contact with the bottom of the recess between the teeth
the rollers being indicated by unshaded circles. As the wheel turns, the roller 2
rolls down the tooth into the position indicated by the shaded circle and the next
roller 3 rolls back into contact with tooth c¹ the other rollers moving back to the
same extent as indicated by the two circles in each case. The improved wheels as
so far described are intended for driving-that is to say for imparting motion to
chains.
In the cases of wheels which are actuated by chains I make the pitches of the
wheel and chain equal when the chain is new but I provide extra clearance between
the teeth as in the cases of the drivers. The drawings on Sheet 3 illustrate the
action of the chain upon such a wheel Fig. 5 representing the chain as when new
and Fig. 6 as when extended through wear. The drawings speak for themselves
but I will point out that in Fig. 5 the chain would act upon five or six teeth at once
whereas in Fig. 6 it would act freely upon only one tooth at once but the tension of
the "slack side of the chain would keep the rollers b c d and e in contact with the
bottoms of the recesses between the teeth.
Although for convenience of description I have referred to the parts of the chain
acted upon by the teeth as rollers it must be understood that in some cases they
might be studs and in others links or blocks. In all cases wherein the teeth of the
driver wheel act upon blocks or link ends I should prefer to make the bottoms of
the recesses and the faces of the blocks or links which come in contact with
such bottoms flat instead of curved as in the case of the example next to be
described.
Fig. 8 illustrates the formation of my improved block chain gearing. In this
example the pitch of the chain exceeds that of the wheel as aforesaid but the chain
is composed of blocks g g linked together and the bottoms of the recesses between
the teeth of the wheel and the faces of the blocks which come in contact with the
wheel are made flat as clearly shown in the fig. Each block is formed with a
corner at and at the base of each tooth is a corner to receive the said corner of
the block. For convenience each block in the example is formed with four corners so
as to make the block regular in figure. The driving tooth of the wheel bears upon
the corner gas seen in the case of the tooth in Fig. 9. The two ends of the
blocks are not " square" but are each formed by two angles exceeding ninety
degrees meeting on the centre line of the block. The reason for this formation is
that it is intended that each block shall roll out of contact with the driving tooth
and I consider the indicated formation to be suited to this rolling action but if
preferred the ends of the blocks may be square or curved. The drawings on
Sheet 5 illustrate this rolling action. In the four figs. the same driving tooth is
represented in different positions. In Fig. 9 the tooth h is driving the block g
the supposition is that the said block is just about to commence to leave the tooth
or otherwise the wheel to leave the block. In Fig. 10 the wheel has slightly turned
and the block has commenced to turn away from the wheel the face g² rolling upon
the tooth. In Fig. 11 the wheel has again turned a little and still more in Fig. 12
In the last named fig. the block has rolled into position to drop off the tooth.
and
The tooth is formed to "let back" the chain in the manner previously described.
The block when rolling from its position in Fig. 9 to its position in Fig. 12 would
"let back" the next block G to the extent indicated by the distance between the
dotted line and the full line or otherwise to an extent equal to the difference between
the pitches of the wheel and chain. When the block G comes against the driving
corner of the next tooth the said block takes the strain and the block g can drop

page_text: away. The rolling might in some cases be continued beyond the indication but the
representation is sufficient to illustrate the action. An important feature of the
combination is the frictional contact between the blocks and the wheel. On
referring to Fig. 8 it will be seen that the blocks marked g will be pressed forcibly
against the flat faces on the wheel and that the frictional contact between the bodies
will tend greatly to relieve the strain upon the driving tooth.
I have found that a large proportion of the driving force is transmitted to the
chain by this frictional contact. If however it should be considered to be advisable
for any reason to make the faces of the blocks curved as is the custom in the cases
of ordinary block chains I should make the faces on the wheel concentric with the
axis the faces on the blocks being made to the same curvature, but I consider the
contact of flat surfaces to be preferable partly for the reason that a chain having
blocks formed with flat surfaces will suit different sizes of wheels.
If preferred for any reason the driving contact might be made with the outer
links instead of with the intermediate link which would take the place of the
block.
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 :-
1) The chain gearing consisting of chain and chain wheels formed as set forth
and indicated.
2) The chain gearing formed substantially as set forth with reference to Figs. 2
to 7 both inclusive of the attached drawings.
3) In chain gearing a driver wheel having a longer pitch than the chain and
having extra clearances or spaces between the teeth as and for the purpose set
forth.
4) In chain gearing a pitch chain of the indicated or of ordinary or suitable con-
struction combined with a driver wheel having teeth of a pitch exceeding the pitch
of the chain so that until the chain is very much worn with use only the tooth
which is about to leave or is leaving the chain acts as a driver and having suitably
long clearance spaces between the teeth and also having teeth so shaped as that the
part propelled by the driver tooth whilst leaving such tooth shall gradually "let
back" the chain to the extent of the differences between the pitches as set forth and
similarly to the indications in the attached drawings.
5) The chain gearing constructed and adapted to act substantially as set forth
and indicated with reference to Figs. 8 to 12 both inclusive of the attached
drawings.
6) The chain gearing consisting of flat faced blocks linked together formed with
corners and adapted to roll upon their ends out of driven contact with the driver
wheel teeth in combination with a wheel formed with flat surfaces between the
teeth and with teeth of a larger pitch than the pitch of the chain and having
clearances between the teeth to suit such increased pitch the teeth being shaped to
engage with corners upon the blocks as set forth and indicated.
Dated this 11th day of December 1891.
DUTTON & FULTON,
1, St. James' Square, Manchester, Agents.