IMPROVEMENTS IN ROCK DRILLS, PART OF WHICH IMPROVEMENTS ARE APPLICABLE TO OTHER DRILLING APPARATUS
Year: 1877

page_text: PROVISIONAL SPECIFICATION left by Philip John Le Gros at the Office of
the Commissioners of Patents on the 26th May 1877.
PHILIP JOHN LE GROS, of 4, Queen Stroot Place, Southwark Bridge, London,
Engineer. "IMPROVEMENTS IN ROCK DRILLS, PART OF WHICH IMPROVEMENTS
ARE APPLICABLE TO OTHER DRILLING APPARATUS."
These improvements consist,-
Istly. In new arrangements for operating the valve motion and the feeding
device which regulates the advance of the cylinder towards the rock.
2ndly. In the arrangement of the rotary and feed ratchets and pawls, these being
also applicable to ratchet braces used for drilling.
3rdly. In the chuck or clamp for holding the bit in the piston rod.
And, 4thly. In improvements in the mode of fixing the machine.
In the first improvement the mode of operating the valve motion and the
feeding device which regulates the advance of the cylinder towards the rock
consists of a single double-ended lever, actuated by the piston, and brought back to
its intermediate position by 2 springs or two small pistons, acting either on a
projection or cam made on the lever shaft, or acting directly on the lever itself, the
distribution of the steam or compressed air being made by using either one or
two pistons working inside cylinders, or one or two slide valves working on faces,
receiving the steam either from their outside or from their inside, this valve or
valves, or piston or pistons, being placed either near the middle of the main
cylinder and sending steam through side ports to the respective ends of the main
cylinder, or at each end of the main cylinder directly over the opening where the
steam is to be supplied to the cylinders, so as to dispense with the side ports. The
motion of the double-ended lever is regulated by the shape of the groove in the
piston so as to be used also to actuate the feeding device either by using a cam
placed on the end of the lever shaft, working a series of levers or cranks, so made
as to vary the rapidity of the feed, or directly by using the motion of the slide
valve rod, touching a tappet or cam at the proper moment when feed is required,
this tappet actuating the feeding pawl and ratchet through a lever or levers. The
motion of the piston is guided by a bar passing inside a nut, so made as not to
reduce the effective area of the piston, such bar being twisted in case of a rotary
motion, or straight in case the piston should be used without any rotary motion,

page_text: In the second improvement, the arrangement of the rotary and feed ratchets and
pawls, I apply to rock drilling machinery the principle of friction wheels for the
arrangement of ratchets and pawls used for the rotary and feed motions, the ratchet
being a cylinder in which one or several grooves are cut, and the pawl being part of
another cylinder fitting these grooves and turning round an axis, so placed as to
release all friction when the ratchet turns in one direction, and to increase it as
soon as the direction of the motion is reversed, the same arrangement being also
applicable to the ordinary ratchet brace, replacing the spring pawl and ratchet.
The third improvement in the chuck or clamp for holding the bit in the piston
rod is by using a collar (protecting the bottom end of the piston rod from any
injury arising from blows) carrying screws acting on a steel piece holding the bit
in its place.
The fourth improvement in the mode of fixing the machine is by using a hinged
collar carrying a cup receiving 'the drill, and so made as to be slackened or made
tight to the column or stand by screwing up the sides opposite to the hinge, and
without touching the bolt holding the rock drill, and made to slide on a column so
as to approach as close as possible to the face to be worked.
Although in the description given steam only has been mentioned, compressed air
will be equally applicable.