IMPROVEMENTS IN BELT PULLEYS
Year: 1881

page_text: LETTERS PATENT to George Pitt, of Sutton, in the County of Surrey, for an
Invention of "IMPROVEMENTS IN BELT PULLEYS." A communication from
abroad by Philip Medart, of the City of St. Louis, State of Missouri, one of
the United States of America.
COMPLETE SPECIFICATION filed by the said George Pitt at the Office of
the Commissioners of Patents on the 25th October 1881.
GEORGE PITT, of Sutton, in the County of Surrey. "IMPROVEMENTS IN BELT
PULLEYS." A communication from abroad by Philip Medart, of the City of St.
Louis, State of Missouri, one of the United States of America.
This Invention relates to that class of belt pulleys composed of a separate spider
or centre and an independent wrought metal rim; and the Invention consists in
certain improvements in the manufacture and structure of such pulleys, whereby
they can be manufactured with economy and facility, and are made perfect in shape
and of accurate balance, as will hereinafter be fully set forth.
The first part of the Invention is illustrated in Figures 1 to 5 inclusive,
Figure 1 being a view, partly in section, of one of the improved pulleys; Figures 2
and 3, detail sectional views showing spoke sockets inserted in the hub; and
Figures 4 and 5, detail views showing different ways of securing bracket lugs upon
the ends of the spokes.
A represents the hub, B the rim, and C the arms of the pulley.
The hub A is formed of cast metal, and the screw threaded sockets a are secured
or incorporated therein in the operation of casting. These sockets may be of
wrought or cast metal and of any suitable shape to be retained firmly in the hub;
Figures 2 and 3 show sockets of different shapes.
I also form an annular oil chamber D in the hub, which communicates with
the bearing of the pulley by small radial openings, and also with the spoke
socket opening, as shown in Figure 1. This chamber is closed by a suitable screw
plug d.

page_text: The arms C are preferably formed of gas tube or wrought metal tubing, the
openings in which communicate with the oil chamber or reservoir D when the
spokes are screwed into their sockets in the hub and form an additional reservoir
for the oil. When the pulley is used as a loose pulley or "idler" its bearing will
be kept properly and constantly oiled. It is not necessary however that the arms
of the pulley should be hollow.
The bracket lugs c, to which the pulley rim is attached, are formed of cast or
wrought metal, and are either screwed thereon, as shown in Figure 5, or riveted,
as shown in Figure 6.
In order to give strength and rigidity to the pulley I form the wrought metal
rim B with an inturned flange or bead b at each edge.
The corner formed by the inturned flange b and the face of the rim can be
slightly rounded, which will prevent the belt from being cut and greatly facilitate
its shipping and unshipping.
The rim B, which may be formed of one or several pieces, is secured to the
bracket lugs by bolts or rivets c², c¹.
By making the hub spokes, brackets, lugs and rim separately and uniting them
as described, pulleys of varying sizes can be produced with great facility. The
necessity of having a pattern for each size of pulley is avoided, and a single pattern
for the hub will answer for all sizes of pulleys for the reason that the arms can be
varied in length to suit the diameter of the pulley required.
The second part of the Invention is illustrated in Figure 6.
The belt pulleys of various kinds in use prior to the date of this Invention
have all been more or less open to the objection of not being accurately balanced.
This defect has been inherent in their structure. Thus while cast pulleys are of
accurate shape they cannot be practically produced of perfect balance owing to the
irregularity of the weight of the metal at different portions of the rim and to
contraction in cooling. And where pulleys of similar character to that herein
shown have been made the spiders have not been properly prepared, that is, the
spiders have not been operated upon so as to make the ends of their arms exactly
concentric with the true centre or axis of the pulley.
The arms of the spider owing to the impracticability of making perfectly
accurate and smooth castings, and to contraction in cooling, will necessarily possess
slight irregularities relatively to the centre of the pulley, and unless these are
removed and the ends of all the arms made exactly concentric with the pulley axis
the completed pulley will of necessity be imperfectly balanced.
Substantially the same is true of composite pulleys of any character, that is to
say, the spider however made will be slightly imperfect in shape, and unless the
irregularities are cured before applying the rim the completed pulley will not be
accurately balanced.
The advantages of having pulleys of absolutely accurate balance and shape are
numerous, and are so well known and sought after by those who use them that it
is not deemed necessary to recite and explain them.
In making the pulley the cast spider A is centred and bored. The ends of the
arms or the faces of the bracket lugs a upon which the rim is laid are then ground
or turned off by any suitable machinery exactly concentric with the axis of the
pulley. By thus preparing the spider the rim B, which is rolled perfectly true
and uniform in shape, will be exactly concentric at every point with the pulley
axis when laid around the spider, and the pulley will therefore be accurately
balanced.
In order to make the pulley even more true in shape and perfectly balanced, I
then grind the rim concentrically with the axis.
The centre of gravity of a pulley thus made is brought to coincide with its
geometrical centre more absolutely than has heretofore been done.
It will be obvious that if the pulley arms are not first ground off concentrically
with the axis all of the inequalities incident to the operation of casting and cooling
would remain as defects in the spider, and would be greatly aggravated by the

page_text: grinding of the rim, because the lengths of the spider arms being unequal without
grinding, when the pulley rim is applied and ground it will be cut away
unequally, in some portions more and in others less, making it unequal in thickness,
so that the final grinding operation in order to make the pulley perfectly circular
will greatly increase its want of balance. But by preparing the spider as above
described all defects are cured and pulleys of true shape and balance are
produced.
The third part of the Invention is illustrated in Figure 7.
The difficulty heretofore met with in this class of composite bell pulley has
been that of forming a perfect joint at the point where the ends of the rim meet,
without the use of an extra amount of metal in all the attaching lugs and a con-
sequent increase in the weight of the pulley spider, the defects arising from the
want of a perfect joint at such point has been a tendency of the ends of the rim
to move past each other in use, causing them to gradually work loose from their
confining rivets.
To effectually overcome these defects this Invention consists,―
First. In forming the bracket lug, over which the joint of the pulley rim is
made of a greater length than the balance of the bracket lugs of the spider arms,
so as to form a perfect and firm support for the ends of the pulley rim, and thereby
overcome the defects above mentioned.
Second. In forming the bracket lug diametrically opposite the bracket lug,
over which the rim joint is made, as above described, of an equal heaviness
therewith, so as to counterbalance the same and thereby produce and evenly
balanced pulley.
The Drawing is a perspective view of a belt pulley (with parts of the rim broken
away) illustrating the Invention.
Referring to the Drawing, the pulley will be seen to consist of a separate
wrought metal rim A attached by means of rivets to bracket lugs upon the ends
of the arms of the pulley spider B.
In the present improvement the joint a of the pulley rim is placed over one of
the bracket lugs c, which lug is made of greater length than the balance of the
bracket lugs, so as to form a perfect and rigid support for the ends of the
pulley rim in manner indicated in the Drawing and for the purpose above
stated.
The bracket lug o', diametrically opposite to the joint lug c, is made of an even
heaviness therewith, or nearly approximating the same as can be accomplished in
the process of casting the same, so as to counterpoise the same and prevent the
pulley from running out of balance in use.
It is preferable in use to make the bracket lug c of a width equal or nearly
equal to that of the pulley rim.
The fourth part of the Invention, which relates to an improved manner of
manufacturing my composite pulleys is illustrated in Figures 8 to 16 inclusive,
Figure 8 being a view of a spider centering machine with a spider_thereon;
Figure 9, a view of a lathe for boring the central bearing of the pulley; Figure 10,
a view of a spider grinding machine; Figures 11 and 12, views of the rim bending
and crowning rolls; Figure 13, a view of a table for fitting the spider to the rim ;
Figure 14, a view of the clamping ring; Figure 15, a view of a machine for drilling
the rivet holes through the rim and the bracket lugs on the spider arms; and
Figure 16, a view of a grinding machine for truing up the faces and edges of the
pulley.
Heretofore considerable difficulty has been encountered in the manufacture of
composite pulleys similar to those herein described, much time, skilled labor, and
large and elaborate machinery have been required, and their production has been
correspondingly expensive.
The object of this Invention is to cheapen and simplify their construction,
overcome the objections above mentioned, and produce strong and perfect pulleys
in a quick and efficient manner.
:

page_text: The Invention, therefore, consists in an improved process of manufacture,
whereby the above results are obtained, as will hereinafter fully be set forth.
The manner in which the Invention is carried out is as follows:
The spider or centre A of the pulley is secured to a chuck B and properly
centred thereon by means of the centering machine C, which for this purpose is
provided with a vertical arbor c, on which the chuck screws, and an adjustable
indicator arm c¹ to show the workman as he turns the spider which parts are out
of centre and what adjustment is required. When the spider has been properly
centered it is securely clamped or bolted to the chuck. The chuck and spider may
now be secured to the arbor of the boring lathe D and the hub bored out to the
required diameter, as is well understood.
above set forth, but it may be
on the lathe or mill D. The
the reception of the set screws
It is preferred to use a centering machine, as
dispensed with if desired and the centering done
usual screw holes can now be bored in the hub for
to secure the pulley to the shaft on which it is to be used.
At this stage the spider may be removed from the chuck B and secured on a
mandrel, which has a screw threaded socket for screwing on the arbors of the
different machines, hereinafter referred to, used in the improved process. But the
arbors of these machines may be adapted to receive the chuck B, and obviously
the boring of the hub above described may be deferred until the pulley is
otherwise completed, or it may be done at any stage of the operation as may be
desirable and expedient. It is preferred, however, to use the screwed mandrel,
as with it there is no danger of the spider or pulley being accidentally forced
out of centre during the several operations undergone in the process of
manufacture.
The spider is now secured to the rotable arbor e of the grinding machine E, and
the ends of its arms are ground off concentric with its axis by the grinder e¹. The
rim for the pulley is bent to the required circle in suitable bending rolls, and may
be straight or "crowned" as is well understood. Rolls F are shown in the
Drawings, Figures 11 and 12, for giving a
« crown" to the rim. The rim as it
comes from the rolls is of sufficient length to allow a slight overlap in applying it
to the spider and has one end filed or finished up square, for the purpose hereinafter
Bet forth.
The spider is now transferred from the grinding machine E to the vertically
adjustable arbor g of the rim fitting table G. This arbor is vertical to the table,
and being adjustable holds the spider at any required height, with the horizontal
central plane of the spider parallel with the face of the fitting table on which the
rim rests as shown, and consequently ensures an accurate fit of the rim to the
spider.
In the Drawings the rim is shown as rolled straight, and the bracket lugs a on
the spider arms, correspondingly ground but when the rim is "crowned 13 the
bracket lugs are ground to fit it.
The rim is applied to the spider in the following manner:-It is placed around
the spider on the fitting table G and firmly drawn or clamped thereon by the
band H. The amount of overlap necessary to be cut off is then accurately marked
on the unfinished end of the rim, the rim removed and the overlap cut off, after
which it is again placed around the spider and the band applied so as to firmly
clamp the two together, the butt joint of the rim being formed on one of the
bracket lugs.
The pulley is now mounted on the rotatable arbor i of a drilling machine I, and
the rivet holes drilled through the rim and bracket lugs. The drill head ' of the
drilling machine is adjustable vertically to drill the rivet holes at different
heights.
When the drilling is completed the partly finished pulley is removed from the
machine and the rim riveted to the spider arms. The band H is then removed
and the pulley is secured on the rotable arbor i of the finishing grinding

page_text: machine J. This arbor has also an endwise and a sidewise movement (the gears of
the machine being secured to their shafts by a groove and feather to permit of
these movements, as will be understood by those familiar with this class of
machinery), which are regulated and adjusted by the screw shafts as shown. The
face of the rim is ground off smoothly by the grinder j, concentric with the axis of
the pulley and from the same centre that the spider arms were ground. The edges
of the rim are now squared or trued up against the sides of the grinder and the
pulley is completed.
Pulleys thus manufactured are perfectly balanced, faultless in shape, strong and
durable, and can be produced more rapidly and at less expense than the imperfect
pulleys heretofore made.
The machinery herein shown and referred to has not been described more in
detail, as its operation will be clear to those skilled in such matters, and no claim
to it is herein made.
Having thus described the improvements, what I claim as the Invention is,-
First. The herein described improvement in the art of manufacturing belt pulley
spiders for composite belt pulleys, which consists in centering the pulley centre or
spider and then grinding the same concentrically with the axis of the pulley,
substantially as set forth.
Second. The herein described improvement in the art of manufacturing belt
pulleys, which consists in centering the pulley centre or spider, boring it, grinding
it concentrically with the axis of the pulley, and then securing the rim thereto,
substantially as described.
Third. The herein described improvement in the art of manufacturing belt
pulleys, which consists in grinding the pulley centre or spider concentrically v
with
the axis of the pulley, securing the rim thereto, and then grinding the rim,
substantially as set forth.
Fourth. The herein described improvement in the art of manufacturing belt
pulleys, which consists in centering the pulley centre or spider, boring the hub
thereof, grinding the centre or spider concentric with the axis of the pulley,
securing the rim thereto, grinding the face of the rim concentric with the axis of
the pulley, and then grinding or squaring the edges of the rim, substantially as set
forth,
Fifth. The improvement in the art of manufacturing belt pulleys, which consists
in centering the pulley centre or spider upon a chuck or mandrel, as herein
described, and then subjecting it to the various operations in the process of manu-
facture without removing it therefrom, whereby all the work is done from a common
centre and absolute accuracy ensured.
Sixth. The improved belt pulley herein described, having the ends of the spider
arms ground off concentrically with the axis of the pulley.
Seventh. The improved belt pulley herein described in which the rim and the
ends of the spider arms are ground off concentrically with the axis of the pulley.
Eighth. A composite belt pulley, having the arm-bracket of its spider or centre
over which the rim joint is made formed of a greater length than the other arm
brackets of the said spider, substantially as herein described and for the purpose
Bet forth.
Ninth. A belt pulley having the arm-bracket diametrically opposite to that over
which the rim joint is made of an approximate length or weight thereto, the
balance of the arm brackets being of a lesser length and weight, all substantially
as herein described and for the purpose set forth.
Tenth. A belt pulley having a wrought metal rim with inturned flanges, for the
purpose set forth.
Eleventh. A belt pulley having a wrought metal rim and an inturned flange at
each edge, the corners or angles formed by the face of the rim, and the inturned
flanges being rounded, substantially as and for the purpose set forth.
Twelfth. The cast belt pulley hub herein described having the socket pieces for
the pulley arms incorporated therein in the operation of casting, as set forth.

page_text: Thirteenth. The combination, substantially as herein set forth, of the cast metal
hub, the independent socket pieces incorporated or secured therein, the pulley arms,
and the rim.
In witness whereof, I, the said George Pitt, have hereunto set my hand and
seal, this Eighteenth day of October, in the year of our Lord One thousand
eight hundred and eighty one.
GEO. PITT. (L.S.)