Improvements in Cycle Chain Adjustments.
Year: 1897

page_text: PROVISIONAL SPECIFICATION.
Improvements in Cycle Chain Adjustments.
I, OLAF PIHLFELDT, of 172, Golden Hillock Road, Small Heath, in the City of
Birmingham, Engineer, do hereby declare the nature of this invention to be as
follows:-
This invention relates to cycle chain adjustments, and has for its object to pro-
vide a means for obtaining parallel adjustment of the back wheel by the rotation
of the hub spindle only and which said means is capable of being employed
particularly in conjunction with the present pattern of chain-adjusting back fork
ends having slot races in which the hub spindle moves.
Threaded upon each end of the back wheel spindle of a bicycle, and coming pre-
ferably on the inner face of the slotted fork end plate, is a spiral-scroll or volute
cam, of the figure technically known as a snail plate, with the edge or periphery
of same terminating in a shoulder or step corresponding in extent to the throw of
the cam and extending from the lowest to the highest point of the volute. I pro-
pose that the middle on the outer side of each cam should have a boss or sleeve
suitable for taking into the slot of the fork end plate, and that the cam should be
made fast to the spindle by any suitable means, such as by a feather of the one part
engaging with a key-way of the other, the said cam being capable of sliding
laterally. The inner face may be sunken for receiving the reduced stepped outer
end of the adjacent bearing cone of the hub. Also located preferably on the inner
side of each fork end plate, and within the path of the movement of the volute cam
is a fixed impingement block or stationary tracing peg, against the opposed end of
which, the edge or periphery of the said cam wipes or traces on the turning of the
spindle for varying the distance between the driving or driven axles, whose
parallelism is maintained by both cams, which have an 'equal throw, being moved
round with the spindle.
The extreme ends of the spindle may have flats or facets for facilitating its
rotation, and inwards of the said ends, it is screwed to take nuts or locking
expedients, by which the hub spindle and the cams are clamped to the fork ends
after adjustment.
The application of my invention to cycles other than those having the ordinary
slotted fork-end plates or back jaws differs in no essential respect from its applica-
tion to the arrangement herein described.
Although I prefer to employ a snail cam as described, yet I wish it to be under-
stood that I may employ an excentric cam of any shape with the same, or nearly
the same, effect.
1007
OLAF PIHLFELDT,
By Henry Skerrett,
Agent for Applicant.

page_text: Improvements in Cycle Chain Adjustments.
I, OLAF PIHLFELDT, of 172, Golden Hillock Road, Small Heath, in the City of
Birmingham, 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 cycle chain adjustments, and has for its object to pro-
vide a means for obtaining parallel adjustment of the back wheel by the rotation
of the hub spindle only and which said means is capable of being employed
particularly in conjunction with the present pattern of chain-adjusting back fork
ends, having slot races in which the hub spindle moves or is traversed.
Figure 1 of the accompanying drawings represents a plan of a portion of the
rear part of a safety bicycle fitted with my improved means for adjusting the drive
chain by altering the position of the back-wheel hub spindle relative to the driving
crank axle, consisting of a pair of snail plates or voluted cams made fast upon and
capable of turning with the hub spindle and adapted, where one end of the said
spindle is turned to wipe against the ends of stationary tracing pegs carried in the
back jaws and arranged to impinge on the peripheries of the said cams.
Figure 2 is a vertical section of the adjustment fittings shown in Figure 1, upon
the dotted line x.
Figures 3, 4 and 5 represent like outside elevations of one of the slotted chain
stay ends and adjusting means and respectively show the snail cam in three
different positions relative to the tracing peg, which determines the position of the
spindle within the slot. Thus, Figure 3 shows the parts in their normal or starting
positions, Figure 4 shows the cam after having made about half its throw and the
spindle moved outwardly along the slot to a corresponding extent, and Figure 5
represents the cam at the end of its spiral throw and the spindle moved as far as
possible outwards or away from the crank axle.
Figure 6 is an inside elevation of the fork end and the adjustment fittings, with
the spindle in section and the several parts in the same positions as in Figure 3.
Figure 7 is an inside elevation of the fork end and the stationary tracing peg, the
spindle and snail plate secured thereon not being shown.!
Figure 8 is a transverse longitudinal section of Figure 7 upon the dotted line r¹,
and Figure 9 is an end elevation of Figure 7:
Figure 10 is an elevation of the wheel hub, with its flatted spindle, and dis-
assembled fittings thereof, comprising the adjusting snail plates, spindle washers
and lock nuts, those adjacent to the right hand end being shown in vertical section
and whilst those at the other end are represented by edge views.
Figure 11 represents front elevations of one of the said cam plates, with spindle
washer and lock nut.
The same letters of reference indicate corresponding parts in Figures 1 to 11 of
the drawings.
Fitted upon each end a¹, of the back wheel spindle a, of a bicycle, and coming
preferably on the inner face of the slotted fork-end plate 61, of the chain stay b,
is a spiral-scroll or voluted cam c, of the figure technically known as a snail plate,

page_text: with the edge or periphery c¹, of same terminating in a shoulder or step ², corre-
sponding in extent to the throw of the cam and extending from the lowest to the
highest point of the volute. I propose that the middle on the outer side of each
cam should have a boss or short sleeve c³, suitable for a chambered sinking or
recess 63, taking into or formed around the edges of the slot 62, of the fork end plate
and coming upon the inner side thereof and that each cam should be made fast
to the spindle by the hole c, therein having flat sides e, taking upon correspond-
ing flats a², on the end of the spindle. The inner face may be chambered or sunken
as at c6, for receiving a reduced or stepped outer end a³, of the adjacent bearing
cone a', of the hub 5. Also located preferably on the inner side of each fork end
plate, and within the path of the movement of the voluted cam is a fixed impinge-
ment block or stationary tracing peg d, against the opposed end d', of which, the
edge or periphery of the said cam wipes or traces on the turning of the spindle
for varying the distance between the driving and driven axles, whose parallelism
is maintained by both cams, which have an equal throw, being moved round with
the spindle.
The extreme ends of the spindle may have flats or facets for facilitating the
rotation of the said spindle and the cams bodily together. These said ends are
also screwed to take nuts or locking expedients f, and washers e, by which the hub
spindle and the cams are clamped to the fork ends after adjustment.
I wish it to be understood that the whole of the voluted periphery of the cam
from the lowest to the highest part of the throw, is operative or available for use
in giving the necessary parallel traverse to the spindle, and that the point of
impingement of the cam against the fixed tracing peg is nearly in the same line
as the centre of the spindle and in the direction of pull of the chain thereon.
Figure 12 represents an elevation of a modified form of my invention in which
the spindle is traversed by means of a pair of plates, made fast so as to turn with
it and each provided on its outer face with a volute channel or box cam, into which
the end of a stationary tracing peg takes.
Figure 13 is a horizontal section of Figure 12 upon the dotted line a².
Figure 14 is a vertical section of the volute-channelled cam plate separately.
c is the cam plate and is the volute channel cut or formed in the outer face
thereof and having an open end 2, to admit of the same being engaged with the
stationary tracing peg d, whose shank 2, is made fast to the slotted fork end
plate b, of the chain stay b. The cam plates are made fast to the axle by similar
means as described in connection with the first form of my invention.
By the tracing pegs, thus being engaged into and confined within the volute
channels of the cam plates, the said cams and pegs are constantly in operative
connection with one another, so that the rotation of the spindle in the one direction
will cause it to traverse outwards within the fork end slots for pulling up or
tightening the chain, whilst when the spindle is turned in the reverse direction it
is drawn inwards and the chain is slackened to a corresponding extent.
The application of my invention to cycles (including tricycles) other than those
having the ordinary slotted fork end plates or back jaws differs in no essential
respect from its application to the arrangements herein described.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim, is:
First: A cycle chain adjustment consisting of a pair of snail plates or voluted
cams made fast upon and capable of turning with the spindle of a driven wheel
and adapted, on the said spindle being turned, to wipe against stationary tracing
pegs or impingements mounted on the frame of the cycle, and so gradually increase
the distance between the said spindle and the crank or driving axle.
Secondly: A cycle chain adjustment, consisting of a pair of boxed or channel
cam plates made fast to, and capable of turning with the spindle of a driven wheel,
and adapted, when the said axle is turned in either direction to run over stationary

page_text: tracing pegs mounted on the frame of the cycle and so gradually increase or decrease
the distance between the said spindle and the crank or driving axle.
Dated this 25th day of March 1808
OLAF PIHLFELDT
By Henry Skerrett,
24, Temple Row, Birmingham, Agent for Applicant.