Improvements in Devices for Fastening Cams, Pulleys, and the like to Shafts.
Year: 1893

page_text: Date of Application, 6th June, 1893-Accepted, 8th July, 1893
COMPLETE SPECIFICATION.
Improvements in Devices for Fastening Cams, Pulleys, and the like
to Shafts.
A communication from abroad by EDWARD A. BLANTON, Jr., of Wallingford, in
the County of Delaware and State of Pennsylvania, United States of
America, Engineer.
1, PHILIP MIDDLETON JUSTICE, of 55 and 56 Chancery Lane, in the County
of Middlesex, Fellow of the Chartered Institute of Patent Agents, 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 an improved device or contrivance for fastening the
cams of stamp mills to the cam shaft and for like purposes such as for fastening
pulleys gear wheels &c. to shafts. It is also applicable for securing cams of any
other machinery, but is more especially useful in stamp mills in which cams wear
out and have to be replaced frequently and it is accordingly illustrated in connection
with a cam of a stamp mill in the accompanying drawing in which :-
Figure 1 is a side view of a cam and end view of a shaft showing the preferred
mode of construction for carrying out this invention.
Figure 2 is an end view of the shaft without the cam.
Figure 3 is a side view of same.
Figure 4 is a side view of a cam and end view of a shaft showing the mode of
applying the invention in the case of mills already built.
Figure 5 is an end elevation of the wedge boss separate from the shaft.
Figure 6 is a side view of same.
The invention consists of an eccentric boss a applied to the shaft b, either
fixedly or separately made and placed on the surface of the shaft together with a
corresponding eccentric recess c in the eye of the cam d, the said boss on shaft and
the recess in the eye of the cam being tangent or nearly so to the surface of the
shaft, and the circle of the eye of the cam respectively, at the beginning and
extending rearward relatively to the direction of rotation a suitable distance
circumferentially on gradually increasing radii so as to constitute a circumferential
wedge or gib on the shaft and wedge cavity in the eye of the cam, whereby the
cam being adjusted by sliding it lengthwise to its position over the wedge boss
whilst inclined forward relatively to the direction in which the cam is to be turned,
and thereby being kept slack of the boss, is then made tight by giving it a sharp
thrust in the other direction and is thereafter kept tight by the reacting effect of
the thrusts of the cam on the tappets of the stamp rods or whatever other device
the cam acts upon.
When the boss or wedge a is made separately from the shaft as in Figures 4,
5 and 6 a short key way or one or more small holes are made in the shaft to
receive a corresponding lug or pins on the thick end of the circular gib and thus
lock the wedge against shifting around the shaft by the thrust of the cam.
Cams fastened with keys frequently work slack, the keys have to be driven very
hard, they are often so battered and bent that it is difficult to get them out when
a cam has to be replaced.
To hold well a key should fit the key ways exactly which they very often do
not and the key ways enlarge by the stretching and compressing of the metal so
that new keys fitted to the original sizes of the key ways are too slack after a
previous keying.
When a new cam is to be put on where another has been keyed the key way of
the cam is of original size, whilst the key way of the shaft is enlarged by the

page_text: effect of the previous key so that the new key cannot fit both and this is a source
of much trouble.
It will be seen that no such difficulties are attendant upon the use of this device.
The cam goes on to its place without difficulty and becomes tight merely by a
slight thrust backward and thereafter keeps tight automatically, and a blow of a
hammer on the end of one of the horns of the cam in the reverse direction
slackens when required.
No amount of use has any deleterious effect on the parts nor interferes in the
slightest with the capacity of the device for keeping tight.
The invention is alike applicable for fastening pulleys, gear wheels and the
like.
Another advantage of this device is that it equalizes the bursting stress around
the hub to a greater extent than a key does, and with it hubs will have to be
banded to re-enforce them against such stress much less frequently because this
stress is locally radial to the key when it is used, whereas with the eccentric boss
it is distributed throughout a circumferential range even greater than that of the
wedge.
It will be evident that the circumferentially wedged projection may be either
on the shaft or the interior of the cam or be separate from both and that the
corresponding depression may be either in the interior of the cam or on the shaft.
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 fastening device for cams, pulleys, gear wheels and the like,
consisting of the eccentric circumferential wedge boss on the shaft and the corre-
sponding eccentric wedge cavity in the eye of the cam, pulley or wheel tangential
or nearly so with the face of the shaft and the circumference of the eye forward
relatively to the direction of rotation and gradually increasing radially backward.
2. The improved fastening device for cams, pulleys gear wheels and the like
consisting of the eccentric circumferential wedge on the shaft, and the corre-
sponding eccentric wedge cavity in the eye of the cam, pulley or wheel, tangential
or nearly so with the face of the shaft and circumference of the eye forward
relatively to the direction of rotation, and gradually increasing radially backward,
the shaft having the recess and the wedge having the lip or rib resting therein.
3. The improved fastening device for cams in stamp mills consisting of a
circumferentially wedged projection on either the shaft or the interior of the cam
or separate from both with corresponding depression in interior of cam or on the
shaft substantially as and for the purpose described.
Dated this 6th day of June 1893.
PHILIP M. JUSTICE.