IMPROVEMENTS IN ROCK DRILLS
Year: 1877

page_text: PROVISIONAL SPECIFICATION left by John Albert Reinhold Hildebrandt
at the Office of the Commissioners of Patents on the 17th November 1877.
A communication from abroad by Friedrich Pelzer, Engineer, of Dortmund, in
Germany.
JOHN ALBERT REINHOLD HILDEBRANDT, Engineer, of 55, Cross Street, in the City
of Manchester, in the County of Lancaster. "IMPROVEMENTS IN ROCK DRILLS."
(A communication from abroad by Friedrich Pelzer, Engineer, of Dortmund, in
Germany).
•
The Invention consists of improvements in rock drills having reciprocating or
percussive action, and relates to the slide valve motion, the automatic and gradual
turning of the tool, the automatic feed, the automatic and continuous removal of
debris or bore waste from the bore hole, and an adjustable stand for the machine.
The slide valve may be of the ordinary D or mushroom type, the valve rod is
actuated by two levers centred near the extremity of the piston rod when at the
ends of the stroke, one end of each moving freely in a slot of the rod while the other
comes in contact with a nut or other projection on the piston rod, so that at the end
of the forward stroke the lever at that end is struck in the same direction and thus
jerks the valve rod backward, the opposite taking place when the piston rod is
about to complete the return stroke. The violence of the action is checked by
buffers and springs placed at each end of the valve chest, india-rubber or other
elastic material which is used for packing usually serving as a spring.
For the purpose of effecting the turning of the tool and the forward movement of
the machine or feed automatically a side lever is employed, which has a cranked end
working in a slide to which the clacks are attached which turn the ratchet wheels;
one of these sits on a square rod which works into the piston rod, the other is
fixed on the nut of the feed screw usually placed immediately below.
The cranked lever just mentioned is pressed by a spring on the same projection
on the piston rod which works the slide valve, and is so constructed that it slides
on it; hence, when the piston rod arrives nearly at the end of the stroke it comes in
contact with the said lever and presses it outward against the pressure of the spring;
the lever moves the slide and with that the clacks.

page_text: The ratchet wheels are so pitched that each stroke of the piston is sure to cause
the ratchet wheel at the end of the piston rod, and with it the rod itself, to turn one
tooth, but the wheel on the feed screw nut is pitched somewhat coarser so that it
always works on the same tooth, so long as the piston makes a stroke of normal
length; but whenever this length is exceeded the point of the clack from the longer
movement of the lever and slide gets over the point of the tooth and consequently
moves the wheel one tooth.
For the purpose of automatically removing the bore dust or waste from the bore
holes, water or other fluid under pressure is employed and applied in the folloi ng
manner:- -The tool usually consists of the actual edge or chisel, the shaft and the
stem, which latter fits into a socket on the forward end of the piston rod, and in
this an internal passage or channel is made by cutting a groove, extending from the
cutting edge or face some distance in the shaft; this groove may be made narrower
at the bottom than at the top, and then closed up with a strip of metal of less
depth than the groove, which is inserted into the latter and hammered or rivetted
over so as to become fixed. An opening is left at each end of the
this forms
groove;
an internal channel with an inlet in the stem and an outlet near the cutting edge
or face of the drill, so that a liquid injected at the stem would issue near the
cutting edge.
Close to the tool socket in the piston rod, but allowing sufficient room for the stroke
of the piston, I pass the shaft of the tool through a box or gland having a stuffing
box at each end, and forming an internal annular space round the shaft of sufficient
length and in such a position that the opening to the channel in the tool is always
within the annular space. This annular space is put into communication with the
reservoir containing the water or other liquid under pressure by means of an
ordinary tube, which is held in one or more eyes in lugs on the cylinder or other
part of the machine, and continued by flexible tubing attached to the other tube
and the reservoir.
A cock or tap may be inserted in any convenient place in the pipe or tube to
regulate or stop the flow of liquid employed.
The passage or channel in the tool may also be produced by rolling, drilling, or
any other convenient way.
The adjustable stand or tripod consists of two bridges provided with eyes for
carrying the spindles of the drill, and rigidly connected by a central bar shrunk
into its place and pinned; it is prolonged at one end so as to form a foot. The two
other feet are attached to the opposite bridge, the ends of which are extended beyond
the eyes provided to hold the inachine; they are formed of split halves, and pivots
are inserted with a nut at the top, and carrying a plate with a central pin and a
quadrant slot below. Each of these two legs is centred at the pin and carries a bolt
moving in the quadrant slot, and may be moved to any angle the latter will
allow; it is fixed in the desired position by screwing up the nut on the bolt in the
quadrant slot.
The legs consist of tubos carrying a solid sliding core at each end, one forming;
the foot, the other being the portion centred and moveable on the quadrant plate
the solid cores are adjustable in the tubes by means of collars and set screws.
As the pivots of the quadrant plates can be turned in any direction and any
angle, and the quadrant plate allowing a further angle of 90° with the centre of the
pivot, thus forming a universal joint, it is clear that the legs may be placed in any
position.
Instead of the eyes provided to hold the machine a saddle may be attached
instead.