Year: 1887

page_text: Date of Application, 9th Mar., 1887.
Specification Accepted, 15th Apr., 1887.
We, RALPH THOMPSON of Backworth and HENDERSON GIBSON, junior, Engineer
of the Grange East Holiwell, both in the Parish of Earsdon, Northumberland 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:
Our invention of improvements in hand power Rock Drills consist in arrangements
whereby 1st the weight of the apparatus is much reduced. 2nd the feed is regulated
automatically in proportion to the effect produced by each blow, 3rd the effect of
sudden variation of strain on the driving handle, due to a cam action is diminished.
We construct a light frame L of cast iron, or any other suitable material having
bearings in it for shafts M, N ; transverse in relation to the drill one to carry the
main driving shaft and the cam arrangement (described later) & one to carry a small
fly wheel, and both to carry a pair of toothed wheels P; or wheels with any suitable
gearing connecting the shafts together, so that the fly wheel shall be driven at a much
greater speed than the main driving shaft and cam; and that it shall thus possess
inertia adequate to take up to some extent the power which at any part of the revolu-
tion may be in excess of the work to be done, and impetus to enable it to give out to
some extent power at other parts of the stroke when the work to be done is in excess
of the average power required. This cast iron frame contains also part of a provision Q.
for attaching the drilling apparatus to a vertical or horizontal support, so as to fix the
drill in any desired direction but this attachment being of any ordinary description
we omit from the drawing for the sake of clearness.
The actual drilling instrument itself consists of a bar of iron or steel, or other
suitable material, having a box at the drill end of it of the usual construction adapted to
receive and hold the tool to be used, and at the other end a plain part with a longi-
tudinal straight key way so as to prevent rotation excepting as desired.-Intermediate
between the two ends of this bar it is screwed so that the whole bar consists, 1st of a
box A., to hold the drilling tool; 2nd a straight and smooth part B, to slide in the
bearing provided for it, this part being of length equal to the stroke, plus the travel
arranged for in the shape of feed, plus the length of bearing and plus convenient
clearances; 3rd of a screwed part Ú, equal to the length of hold in the toothed rack,
afterwards described, plus the desired length of feed and lastly of a plain part D,
adapted to slide in a bearing (but with a longitudinal key way cut in it) this part
being of length equal to the length of the other plain end plus length for the feed
wheel seated upon it afterwards described, and plus the length of a squared part E on

page_text: which a handle can be fitted so as to revolve the screw by hand.-On the screw part
of this drilling bar and nearly over the centre of the cam afterwards described we
screw on by the screw of the drilling bar a toothed rack F. capable of engaging with
the cams afterwards described by means of one or other of its teeth and we place a
spring or springs abutting against the bearing of the hinder end of the bar at one end
and against a provision made for it on this toothed rack piece at the other end which
spring or springs may be cased in a tube or left open as desired. The springs are
omitted in the drawing to avoid complication. We introduce a further provision on
this toothed rack to regulate the feed of the drill which consists of two light jaws G.
fitting to a rectangular bar H. one on each side of it. This rectangular bar is twisted
so as that when the jaws move backwards and forwards upon it the bar must twist
more or less, or move backwards and forwards in a rotary direction, the twist, we make
is not uniform, that is to say if the movement of the jaws on the bar is a short
movement, the twist, or rotation of the bar is very slight, but if the movement of the
jaws along the bar be a long movement, the jaws come in contact with a part of the
twisted bar, where the twist becomes quicker, and where therefore the movement of
rotation is greater. The rotary and retrograde movement of the bar actuates the feed
by any ordinary appliance such as a pall and ratchet wheel I, and by the varying twist
of the bar the feed is automatically made more rapid when the cutting effect of
the drill is greatest and less rapid when the cutting effect of the drill is less.
There is a cam wheel J. for actuating the reciprocating movement of the drilling
bar which may be of any ordinary construction and with two, three or four cams upon
it, each cam in turn engages in one of the teeth of the rack described and forces the
drilling bar back against the spring until by the revolution of the cam the rack escapes,
when the recoil of the spring delivers the desired blow through the drill and drilling
bar and the feed is operated to the required extent for a second blow and so on.-The
drill is at the same time partially revolved as will be readily understood by the re olu-
tion of the feeding wheel which is keyed to the longitudinal slot of the drilling bar.-
We also introduce guides for the toothed rack which however to prevent complication
are not shewn in the drawing.
K. is the path of the driving handle.--In consequence of the gradual feed of the
drill the toothed rack moves into different positions in reference to the cam at each
stroke, and it is therefore possible especially as the cam and teeth wear that in certain
positions the end of the cam might fall on the 'top of a tooth of the toothed rack instead
of in front of it, and to meet this difficulty and to avoid risk of bending the drilling
bar we provide a spring arrangement by which the toothed rack shall be released
from this position and the cam end shall fall upon the tooth next to that on which it
fouled.
our said
Having now particularly described and ascertained the nature of
Invention and in what manner the same is to be performed we declare that what
we claim is :-
The arrangement of drilling apparatus consisting of all or any of the parts
following:
1st. The automatically varied feed according to the effect produced by each blow.
2nd. The toothed rack arrangement.
3rd. The application of quick speeded fly wheel all substantially as described.
Dated this Seventh day of March 1887.