IMPROVEMENTS IN FEED MOTION MECHANISM MORE ESPECIALY ADAPTED FOR USE WITH HAND HAND ROCK DRILLS SCREW LIFTING JACKS SCREW PRESSES AND THE LIKE
Year: 1884

page_text: PROVISIONAL SPECIFICATION.
I, JOHN DAVISON of Bells Close Engine Works, Scotswood Newcastle on Tyno,
Engineer, do hereby declare the nature of my invention for "IMPROVEMENTS IN
FEED MOTION MECHANISM MORE ESPECIALY ADAPTED FOR USE WITH HAND
HAND ROCK DRILLS SCREW LIFTING JACKS SCREW PRESSES AND THE LIKE to
be as follows :—
Hithertoo in hand rock drilling the feeding forward of the drill has been effected
by means of a Screw Spindle working in a nut fixed to the frame of the Machino
and when working with hard rock tho pitch of the Screw has had to be very small,
and in consequence the threads have soon become stripped, In my invention
I obviate this difficulty by putting on the spindle as trong thread of say '/'" or
1/inch pitch but instead of having the nut fixed as heretofore I give it a rotary
motion which may approximate to that of the spindle, by this means I get a
differential feed which may be varied according to the difference of speeds of the
spindle and nut, In carrying my invention into effect I cast in one piece with
the nut and at one end a toothed wheel and at the other a Flange and I clasp
the portion between the flange and wheel by a crosspiece which is mounted on the
frame of the machine.
This crosspicce allows the nut to turn freely in its bearing and it has also a
second bearing for a collar bolt which carries at each end a pinion; one of which
gears with the wheel on the nut and the other with a wheel mounted loosely on
the screw spindle above the nut but turning with it by means of a feather sliding
in a longitudinal keyway in spindle, By suitably proportioning the change wheels
it is evident that the motion of the spindle can be transmitted to the nut in any
given velocity ratios.
In connection with the change wheels aforesaid I may use an arrangement for
reversing the motion of the nut and so gain a quicker feed than the pitch of the
Screw, Also I may use an arrangement with the change wheels aforesaid for
throwing then out of gear and by dropping a catch into the teeth of the nut render
it a fixed nut, Both of the last mentioned arrangements will be usefull for a quick
return of the feed screw and in soft material such as coal and the like.

page_text: In the above mentioned mentioned description the Screw spindle is of the kind
ordinarily used, that is to say, one having a loose socket at one end to hold the
twisted augur drill, but in sone cases I may dispece with the spindle and mount
the differential gear above decribed on the drill itself, In this the thread of the
nut takes the form of two steel pins between which the helical web of the drill
passes.
Though I have described my inention with reference to rock drills it is evident
it is equally appicable to Screw Jacks screw presses and the like where a slow
feed is required under a great pressure.

page_text: Improvements in Feed Motion Mechanism more Especially
Adapted for Use with Hand Rock Drills, Screw Lifting Jacks,
I JOHN DAVISON of Bell's Close Engine Works, Scotswood, Newcastle on Tyne,
Engineer, do hereby declare the nature of my invention for IMPROVEMENTS IN
FEED MOTION MECHANISM MORE ESPECIALLY ADAPTED FOR USE WITH HAND ROCK.
DRILLS, SCREW LIFTING JACKS SCREW PRESSES AND THE LIKE and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :—
Hitherto in hand rock Drilling with Augur Drills the feeding of the drill has
been effected by means of a spindle working in a nut fixed to the frame of the drill
and when working with hard rock the pitch of the screw has had to be very small
and in consequence the threads have soon become stripped-In my invention
I obviate this difficulty by putting on the Spindle a strong thread of sny 1/4" or
"pitch but instead of having the nut fixed as heretofore I give it a rotary
motion which may approximate to that of the spindle, by this means I get a
differential feed which may be varied according to the difference of speeds of the
spindle and nut.
In carrying my invention into effect I make the nut with a thick Collar at one
end and I fit this nut into a cross-piece which is mounted on the frame of the drill,
this cross-piece allows the nut to turn freely in its bearing and it has also a second
bearing for a spindle which carries at each end a pinion one of which is cast in one
piece with the spindle and the other fitted to the spindle by a feather and nut, one
of these pinions gear with a wheel mounted loosely on the Screw spindle behind
the nut but turning with the screw spindle by means of a feather sliding in a
longitudinal keyway cut the full length of the screw spindle, the other pinion gears
with a hollow wheel mounted loosely on the screw spindle in front of the nut, but
not turning with it-the hollow part of this wheel covers the part of the nut
collar projecting beyond the thickness of the crosspiece and in this part of the nut-
collar is fitted one or more spring pawls engaging a suitable stop piece formed on
the interior rim of the hollow wheel-so that as this wheel revolves it carries
with it the nut in one direction only-On the other face of the nut-collar a stop
piece is formed to receive a spring pawl which slides in a recess formed in the cross-
picce, the stop piece on this part of the nut-collar is so formed that when the
motion of the screw spindle is reversed the pawl will prevent the nut revolving
and thus make the nut a fixed one during the return motion of the screw spindle-
By suitably proportioning the change wheels it is evident that the motion of the
spindle can be transmitted to the nut in any required velocity ratio and also by
placing the pawls and stops as herein described, the return motion of the screw
spindle will be at the speed due to the full pitch of the thread-As the action of
the pawls being in contrary directions in the nut collar the reverse motion of the

page_text: Refering to Sheet of Drawings a represents slotted Screw Spindle.
B Rotary Nut.
C. Cross piece.
D Change Wheel.
E Change Pinion.
F1 Pinion and Spindle.
F Hollow Wheel with stop piece.
G Spring Pawl in outer face of Nut Collar.
H Spring Pawl in recess of cross piece.
I Front plate for retaining Wheel F in position.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I would have it
understood that I do not claim in general the principle herein before set-forth and 1
embodied in the Mechanism illustrated in the Drawings but what I do claim is
1st In rock drilling machines the method of feeding the drill differentially by
means of a screw A and rotary nut B the nut recoiving its motion from the bcrew
by means of change wheels D. E. F¹ and F and being capable of being locked to
form a fixed nut substantially as and for the purpose hereinbefore set-forth.
2nd In rock drilling machines the combination of parts forming the feed motion
Mechanism hereinbefore described and consisting of the Screw A the nut B deriving
its motion from the screw by means of the change wheels D. E. F¹ and F? and the
pawl ratchet G and H with the cross-piece C.
3rd The application of the above described differential Mechanism to screw
presses screw lifting Jacks and the like.
TOLL
Th
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