IMPROVEMENTS IN OBTAINING VARYING ROTARY MOTION
Year: 1884

page_text: I GEORGE MASON 67 Bradshawgate, Bolton Lancashire, Engineer, do hereby
declare the nature of said Invention for IMPROVEMENTS IN OBTAINING VARYING
ROTARY MOTION and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:-
The object of my Invention is to convert a uniform rotary motion into a
differential rotary motion in such a manner that the speed of the differentially-
rotated shaft will, during a portion of the revolution of said shaft, be gradually
increased, and during the other portion of the revolution will be gradually
decreased, both increase and decrease being uniform in character, and the changes
being effected without jar.
In the accompanying Sheet of Drawings, Fig. 1 is a side view, partly in section,"
of the devices comprising said improvements in obtaining varying rotary motion.
Fig. 2, a transverse section on the line 1, 2, and Fig. 3 a plan view.
A is a shaft, to which a uniform rotating movement is imparted in any suitable
manner, and B is a shaft to which a differential rotating movement has to be
imparted from the shaft A, both shafts A and B being adapted to suitable bearings
on a bracket or stand, E. The shaft A has a crank-arm, a, and the shaft Ba a
similar crank-arm, b, both arms being slotted for the reception of sliding boxes, e,
and f, through which passes a pin, d, which may be suitably secured to one of the
boxes to prevent longitudinal displacement. The shafts A and B are set out of
line with each other that is to say, they are in the same vertical plane; but the
axis of the shaft B is somewhat below that of the shaft A.
A differential-motion apparatus has been heretofore devised in which are
employed the two shafts set out of line and having crank-arms and a crank-pin
common to both; but in such case the pin was secured to the crank-arm of one
shaft and adapted to a slot in the crank-arm of the other shaft, the consequence of
this arrangement being that the speed of the driven shaft is not gradually increased
during one portion of the revolution of the shaft and then gradually decreased
during the other portion of the revolution, and the device is impracticable for

page_text: many purposes. This objection I overcome by making the crank-pin adjustable
radially in respect to the driving shaft, and by causing it to move from and
toward said shaft as the latter revolves. This movement is effected by the
cams D D, secured to the stand E, and having slots for the reception of the rollers
d', d¹, on the projecting ends of the crank-pin d, d, so that as the shaft A rotates
the rollers are caused to traverse the slots, the shape of the latter thus determining
the position of the crank-pin in respect to the shaft A, so that by properly
governing the radial movement of said pin the speed of the shaft B can be regulated
⚫as desired.
The boxes e and fare grooved to prevent lateral displacement, in connection
with each box I use a filling-block, i, interposed between the box and one of the
wings of the slotted crank-arm, said wing being tapered or inclined on the inner
edge, so that each block i acts as a wedge, and by radially adjusting said blocks
any looseness caused by wear of boxes can readily be compensated for. To secure
the blocks in position, set-screws, k, passing through slots in the crank-arm, are
employed.
In carrying out my Invention the exact construction of parts shown need not be
adhered to in all cases. For instance, the boxes e and f may be dispensed with
and the crank-pin itself adapted to the slots of the crank-arms. In some cases one
cam may be sufficient and the other cam left out, or the crank pin may have
pivoted sleeves adapted to slide on the crank-arms, the latter in such cases being
simple rods without slots.
The bracket or stand E may be modified to suit the purpose required.
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 combination of the two shafts A and B, set out of line with each other,
and each having a crank-arm with a crank-pin common to both arms, and a cam
or cams D, for radially shifting said pins as the shafts revolve.
2 The combination of the shafts A B, set out of line, the slotted crank-arms a b
the sliding blocks é f; pin d, and cam or cams D as set forth.
3-The combination of the shafts A B, set out of line, the slotted crank-arms a b,
the sliding blocks ef, and the wedge-blocks i, as set forth.
Dated this 20th dev of March 1884
GEORGE MASON,
67, Bradshawgate, Bolton.