IMPROVEMENTS IN MACHINES FOR DRILLING OR BORING ROCKS
Year: 1868

page_text: PROVISIONAL SPECIFICATION left by John Breedon Everard at the
Office of the Commissioners of Patents, with his Petition, on
the 16th December 1868.
I, JOHN BREEDON EVERARD, of Leicester, in the County of Leicester,
do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN MACHINES FOR DRILLING OR BORING ROCKS," to be as follows:-
This Invention consists in improvements in the construction of drilling
jumpers," in
or boring machines belonging to the class known as "
which motion is communicated direct from the steam or other cylinder,
the drill being in fact a continuation of the piston rod.
The machine in its essential particulars consists of a cylinder, with its
necessary valve chest, valve, piston, piston rod, guides, and slides,
mounted on a metal ring, on opposite sides of which ring (herein-after
called the "inner ring") pivots are fastened which work into bearings
or carriages adjustable upon another ring called the "outer ring," which
is made of a circular form and arranged concentrically with the cylinder.
By this method of mounting the cylinder may be inclined in any
direction, having a moderate divergence from the centre line of the

page_text: machine. To the "outer ring" three metallic legs are fastened,
the same being at a short distance from their lower extremities secured to
another circular ring, which may be termed the "lower ring." The legs
may be made in two parts, one part sliding over the other and adjustable
by means of bolts or sliding clips to varying lengths so as to suit the
inequalities of the surface. The cylinder is of ordinary construction and
has two stuffing boxes. The slide valve for regulating the steam may
be of any suitable construction by which rapid speed may be attained,
but for ordinary machines a cylindrical balance valve is by preference
used, and that for actuating the upper side of the piston only, the
under side, which (in consequence of the larger diameter of the piston
rod) is of less area than the upper, being always open to the steam pipe.
The valve is actuated by an arm from the piston rod cross head striking
at each end of the stroke nuts which are placed at proper distances on
the valve rod. The piston rod is in two parts, each composed of a hollow
cylinder, but of different diameters, that part-above the piston, and which
passes through the upper stuffing box of the cylinder, having an internal
diameter of sufficient size to allow the largest drill used to pass through.
At its upper end is a cross head which works in slides fastened to the
"inner ring" of the frame, and which carrics the before-mentioned arm for
actuating the valve. The cross head in addition to guiding the piston is
used to keep the piston rod from being turned by the rotating gear. The
two slide bars are joined at the top by a cross piece, which also has a hole
in the centre for the passage of the drill, and under which are two strong
springs to prevent any jar from the recoil of the piston rod. The hollow
cylinder forming the bottom part of the piston rod has a sufficient
internal diameter to admit of the free working of a screw therein, which
screw, together with the shaft, of which it forms the upper part, is
hollow, having a sufficient internal diameter to admit of the passage
through it of a similar drill, as before mentioned. This hollow arrange-
ment of the piston rod is not, however, in all cases necessary. The drill
is firmly keyed to the lower end of the screw shaft. The screw works
through a similarly tapped nut secured to the bottom of the piston rod,
and the drill is fed forward by the rotation of the screw. The lower
part of the before-mentioned screw shaft is made angular, or with a
key slot, or in any other known way by which a continuous rotary
motion may be communicated from one working part to another, and
the shaft works through a bearing which is in effect the boss of a toothed
wheel. Any rotary motion given to the wheel is imparted to the shaft,

page_text: which may be in consequence unscrewed from the nut and fed forward,
or screwed in and withdrawn. To prevent the reciprocating motion of
the piston rod being communicated to the wheel it rotates in a generally
fixed bearing, which at the will of the operator may be adjusted on and
securely fastened to slides, the latter being in their turn adjustable (if
necessary) on and capable of being secured to the before-mentioned
"lower ring" of the frame. A hinged rod, which acts parallel to the
screw shaft and works through a part of the same bearing as the toothed
wheel, is securely fastened to the piston rod and receives from it a
similar reciprocating motion. Attached to the lower end of this rod,
and so arranged as to work into the teeth of the wheel, is a steel spring
which slips under one of the teeth of the wheel when the piston is at the
bottom of the stroke, and upon the return stroke gives the wheel a
partial turn. If, however, the rock should be harder than usual, the
feed gear may after a certain number of blows force the tool out too far,
and the stroke of the piston will be gradually diminished, and after a
time the spring in passing under the wheel may be caught, and by the
upstroke broken. To remedy this defect a bent arm is attached to
the before-mentioned hinged rod, which arm carries at its extremity
another spring acting nearly at right angles to the first-mentioned spring
and being in position near the top thereof. The spring attached to the
bent arm is so placed that when the piston is at the bottom of the stroke
it shall just touch the top of the toothed wheel, and its office is to hold
back the main spring until the stroke is quite confplete, when the latter,
having then room to pass safely under the wheel, is released by the
upper or catch spring coming in contact with one of the teeth. It will
thus be seen that if from any cause the stroke is not fully completed
the mainspring is not released, and therefore as the wheel does not rotate
the blow is repeated in the samo place. By these means the rate of feed
is adjusted to the varying nature of the resistance.
Although steam has been herein mentioned as the motive power, any
other suitable clastic fluid may be employed.
The mode in which the machine is worked is as follows:-Three
properly shaped holes are drilled in suitable positions round the site of
or other bolt inserted in each.
the proposed blast hole, and a "Lewis
The machine is then placed in the required position and chains or ropes
are stretched from the bolts to lugs fastened on the "outer ring." The
chains or ropes are tightened by means of ordinary right and left screw

page_text: blocks. When the machine is used for drilling "shot holes," that is,
holes in large stones, it is attached by passing chains partly round and
under the stone, and then tightening the same as before mentioned. If
required to be used as a tunnel or heading drill it is necessary to attach
the working parts to a suitable adjustable frame. The frame having
been secured to the face of the rock the exact direction of the holes is
determined on and the cylinder adjusted thereto, the toothed wheel
bearing being similarly adjusted. The drill, which for a certain part of
its length has keyholes formed in it at regular intervals, is dropped down
the central hole of the piston rod and is keyed to the end of the screw
shaft. The spring and wheel are then thrown out of gear by turning
the rod a little on its hinge, and the screw is so adjusted that the point
of the drill shall just touch the rock when the piston is at the end of its
advance stroke. The steam is then turned on, and the continuous
pressure under the piston drives it up. At the end of the stroke the
valve is lifted-and-the-upper-side of the piston opened to the steam pipe,
and it is driven to the bottom. In its descent or advance the mainspring
is forced by one of the teeth of the wheel past the end of the catch
spring, where it remains locked until the catch spring comes in contact
with the wheel when it is released, and passing under a tooth is ready
upon the return stroke to give the wheel a partial turn. This return
stroke is produced by the opening of the exhaust port, when the action
of the steam below the piston again drives it up, and the preceding
operation is repeated. The wheel being partially turned gives a corrc-
sponding motion to the screw, which is thus fed forward taking the drill
with it. A spring pawl fastened to the fixed bearing prevents the return
of the wheel. When the drill has penetrated to a certain depth the key
is passed through a higher hole in the drill rod; or, if necessary, a new
drill is inserted and the screw adjusted as before, when a similar action
again takes place.