Improvements in and relating to Automatic Belt Shifting : 1 Mechanism.
Year: 1895

page_text: Date of Application, 5th Nov., 1895-Accepted, 7th Dec.. 1895.
COMPLETE SPECIFICATION.
Improvements in and relating to Automatic Belt Shifting :
1
Mechanism.
I, GEORGE ANDREW SMITH, a citizen of the United States of America,
residing at Cohoke, in the County of King William and State of Virginia, one
of the United States of America, 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 :-
My invention more especially relates to improvements in the class of belt
shifting devices in which the operating shaft has a central fixed or drive pulley
and a pair of loose pulleys, a straight and a crossed belt; and in which the bar
is automatically shifted by a movable portion of the machine operated by the
operating shaft, such, for instance, as the reciprocating carriage of a knife grinding
machine or a planing machine. I desire it understood, however, that while my
invention is more especially adapted for use in connection with an automatically
reciprocated operating rod or bar, it is also applicable and useful in connection with
a band operated bar.
In the practical application of belt shifting of the class above described, the
belt engaging members are shifted laterally by suitable means connected with
the operating rod or bar, by a rigid member, by means of which the belt shifting
member is reciprocated.
From practical experience with this class of shifting devices I have found, that
the action thereof is not positive, and frequently is such, especially when shifting
the crossed belt from the loose to the fixed pulley, as to leave both belts upon the
loose pulleys, and in consequence cause a complete stoppage of the machine at
each end of the reciprocal stroke of the carriage or other movable body operated
by the drive shaft.
This stoppage generally occurs when the vibrating or swinging arm which
operates the belt members (when such device is used) is at or near a dead centre,
and when the relation of the belts simultaneously is such, that the belt last on the
fixed drive pulley has been shifted to the loose pulley and the other belt has not as
yet fully or partly left the loose pulley, thereby leaving both belts upon the loose
pulleys, causing, as it were, a stoppage of the drive shaft, and in consequence,
a stoppage of further movement of the belt shifting mechanism.
This objectionable feature I positively overcome by the use of my invention,
which, primarily, has for its cbject to provide a belt shifting mechanism com-
prising means which will automatically finish the shift or impart the final
movement of the stroke of the vibrating member or other belt throwing means,
irrespective of the further movement of the operating rod or bar after the belt
last on the fast pulley is shifted from the engagement therewith.
My invention also has for its object to provide a belt shifting mechanism in
which the shifting action will be positive and continuous irrespective of the
position of the belts on the pulleys, or the action of the operating rod or bar
after such bar will have brought the vibrating or shifting member to or near a
dead centre, or other predetermined position.
Furthermore, my invention has for its object to provide a belt shifting
mechanism comprising means, which, when acted upon by the first part of the
movement of the operating rod or bar, will store up power sufficient to cause
the vibrating arm to move continuously to the completion of its stroke as the
operating rod or bar stops.

page_text: With other objects in view which hereinafter will be referred to, my invention
consists in a shifting mechanism embodying the peculiar combination and novel
arrangement of parts, such as will be first described in detail and then be specifically
pointed out in the appended claims, reference being had to the accompanying
drawing, in which-
Figure 1 is a perspective view of a grinding machine with my improved belt
shifting mechanism applied, the belts being adjusted to move the carriage to the
position indicated by the arrow.
Figure 2 is a side elevation of the machine with my improvements applied, the
belts being set to move the carriage in a direction opposite to that shown in
Figure 1.
Figure 3 is a view illustrating a different way of arranging such mechanism.
Figure 4. is a detail view illustrating the manner of connecting the vibrating
arm and the operating rod or bar and means for adjusting the normal tension of
the spring.
:
Figure 5 illustrates a position of the belts and the vibrating arm, in full
lines, and the position to which they are brought by the yielding connection,
in dotted lines, such position being attained instantly after the carriage and
operating shaft is momentarily stopped and the fast pulley free of either of
the belts.
Figure 6 is a similar view illustrating an old form of shifting devices in
which the vibrating member and operating rod or bar are connected by a rigid
member, and illustrating the position the belts frequently assume when the
vibrating arm is at, or near a dead centre, and at which position it remains
until shifted further by hand when such rigid connection is used.
Referring now to the accompanying drawing, A, indicates the main frame of the
grinding, planing, or other machine, B the main drive shaft or feed screw therefor,
C the carriage or reciprocating portion, D, D¹ the loose pulleys, E the central or
fast pulley, and F, F' the straight and crossed belts respectively, all of which may
be of any ordinary construction, and will hereinafter be therefore only referred to
in a general way.
The belt shifting devices in the preferred form, are arranged as shown in
Figure 1, and comprise a laterally movable belt shifting member or bar G, held to
reciprocate in bearings g g projected up from the main frame of the machine, as
clearly shown.
To the front end of this bar G is pivotally connected the inner crank end h of a
rocker or vibrating member H, which has a corresponding crank arm ¹ on the
outer end, such arms and in the construction shown in the said Figure 1
projecting upward.
J indicates the reciprocating operating rod or bar, which in the preferred
form is held to reciprocate in bearings j, j, ou one of the side beams of the
main frame, and has adjustable stops which are adapted to be engaged by
the carriage at the end of each reciprocal movement thereof, as clearly shown
in Figure 1.
L indicates a yielding or elastic connection such as It stout coil spring, the
ends of which are connected to eyes M and N which are adjustably connected
to the operating rod or bar and to the upper end of the vibrating arm
such adjusting means being provided to regulate the normal tension of the
spring L.
This spring L it will be observed forms a yielding connection between the
arm and the reciprocating rod or bar J, the normal tensiou of which can be
readily adjusted by setting the eyes M and N as desired, which tension however, it
should be stated, is further and materially increased by the last portion of each
stroke of the operating rod or bar J, which increased tension forms the stored up
power or energy utilized to continue or complete the shitting action of the vibrating
arm Hand shifting member.

page_text: This operation is best explained as follows :
The parts being in the position shown in Figure 1, and the carriage travelling in
the direction indicated by the arrow, and the spring inclined toward the end of the
machine: 'now it will be readily seen that as the carriage above reaches the end of
its reciprocal movement indicated, it engages the stopj' and pulls the operating
rod or bar in the same direction, which, as it thus moves, carries the spring L to
the diagonal or inclined position, directly reverse to that shown in Figure 1, the
yielding condition of the spring member L permitting it to assume such position
without affecting the arm /.
After reaching this latter position, however, further movement of the bar J, will
cause the spring to pull upon the arm and in consequence rock the member H
and move the bar G and begin to shift the belts.
At this point it should be stated, the normal tension of the spring L is less than
the frictional resistance of the belts on the pulleys. It will thus be seen that as
the bar or rod J, continues in its movement it will first draw ont the spring, and
increase its tensile pull or strain to a point sufficient to overcome the frictional
resistance of the belts on the pulleys, especially that of the belt on the fast
pulley. When this occurs it is manifest the member L becomes a pull member
and serves to rock the arm as the bar J pulls it in the direction of its (the bar J)
movement.
Thus it will be seen the tensile and retractile qualities of the spring corre-
spondingly increase as such spring is drawn out, and a stored up power obtained by
the said increased tension of the spring which in itself becomes more effective with
the decrease of the frictional resistance produced by the drive belt as it leaves the
fast pulley; such conditions serving to cause a positive movement of the members H
and G to their final stroke, the instant the last drive belt leaves the fast pulley, no
matter whether the operating shaft and its reciprocating carriage continue in their
movement or come to a momentary stoppage at each reversal of movement of the
machine; it being obvious that the belt moving from the loose pulley onto the
fast pulley produces no resistance to the movement of the bar G, but on
the contrary, serves when partly moved onto the fast pulley to aid such bar in
its final movement.
By reference to Figures 5 and 6 the general operation of my invention will be
readily understood. In Figure 6 I have shown a position the belts frequently
assume in the arrangement of shifting devices having a rigid connecting arm during
the shifting operation, the slow or impeded movement of the cross belt being caused
by the irregular manner in which the shifting fingers engage the belts and the
twist or turn movement of the crossed belt.
Now, were the vibrating or rocker member H connected to the bar J by a rigid
member as shown in Figure 6, it will be manifest that as the belts assume the
position shown, the shifting device would also come to a standstill and leave the
belts on the loose pulleys. Now, when the devices are constructed with a yielding
or elastic connecting member as shown in Figure 5, it will be clear that should. the
several parts be in the position shown in full lines and the machine come to a stop,
by the absence of a belt on the fast pulley, the stored up power or energy, i.e., the
tension of the spring, will swing the vibrating member H to a further stroke and
pull the cross belt onto the fast pulley, as indicated in dotted lines.
While I have shown my improvements as applied to a knife grinding machine,
it is manifest that the same may be employed in connection with any machine for
which the class of shifting devices above referred to are adapted for use.
Furthermore, the same may be used in connection with a hand operated bar,
as the spring connection will act upon the member H as soon as the said bar
reaches a predetermined point and the increased tension produced by the
drawing out of the spring is greater than the frictional resistance of the belts.
From the foregoing description it will be manifest that as one belt is removed
from the last pulley by a direct action of the machine, and the machine in con-
sequence is stopped, the other belt will be shifted onto the fast pulley by automatic

page_text: means, which operate entirely independent of and without any action of the
machine whatever, such automatic power having been stored up by the operation of
the machine as the last drive belt is removed, from the fast pulley.
I
It will also be i oticed that it is only necessary to employ one yielding connection,
as the spring L connecting the rod or bar J. and the rocking member H, is shifted
back and forth,' as most clearly shown in Figures 1 and 2; thus, in Figure 1, the
spring is thrown over to the position shown in Figure 2 before it becomes distended
and operates, and after it operates in this position it returns to the position shown
in Figure 1, before it operates to re-shift the belts.
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 :-
1. In a device of the character described, the combination with the pulleys and
belts, of the shifting bar, the vibrating or rocking member, for operating the same,
the operating red or bar, and an elastic connection between said member and bar, said
elastic connection being adapted to receive power or energy through the operating
rod and transmit the same to the vibrating member, the force or energy of said
connection exceeding the frictional resistance between the belts and pulleys,
substantially as shown and described.
2. The combination with the pulleys and belts of a shifting member adapted
to move said belts, the vibrating or rocking member for operating said shifter,
the operating rod or bar, and the single elastic or yielding connection between the
end of the vibrating member and operating rod, said elastic or yielding member
being adapted to operate when said operating rod moves in either direction,
substantially as shown and described.
3. A belt shifting mechanism as described, in combination with the drive shaft,
the fast and loose pulleys, and the crossed and straight belts, of an operating rod
or bar automatically and intermittently reciprocated, a vibrating or rocker member,
a laterally movable shifter member operated by the oscillation of the rocker
member, and a coil spring connection between such member and the operating rod
or bar, substantially as shown and for the purposes described.
4. The combination in a belt shifting mechanism as described, of the belt shifting
rocker member, the operating rod or bar, the spring L, and the adjustable eyes M
and N connecting the said spring to the operating rod or bar and rocker member,
all arranged substantially as shown.
5. The combination with the drive shaft having a pair of loose pulleys and an
intermediate fast. pulley, a straight and crossed belt held to engage the same, of a
reciprocating operating rod or bar, a reciprocating belt shifting member, an
oscillating member for moving such belt shifting member laterally, said oscillating
member having a crank arm and a spring connecting the said crank arm, the
operating rod or bar having a normal tensile strain less than the normal frictional
resistance of the belts when one of such belts is applied on the fast pulley, as set
forth.
6. The combination with the drive shaft, and pulleys thereon, the belts and the
operating rod or bar J, actuated from the said drive shaft, of the member G having
oppositely projecting belt engaging fingers, the rocking member H, connected with
the member G having a crank arm and the yielding connection joining the
rocking member H and the shifting bar, all arranged substantially as shown and
described.
Dated this 5th day of November 1905
JENSEN & SON,
77 Chancery Lane, London, W.C., Patent Agents.