IMPROVEMENTS IN ROCK DRILLS
Year: 1877

page_text: PROVISIONAL SPECIFICATION left by Ernest de Pass at the Office of the
Commissioners of Patents on the 30th October 1877. [A communication from
abroad by Arvid Henry Elliott, of New York, in the United States of America,
Gentleman.]
ERNEST. DE PASS, of Fleet Chambers, 68, Fleet Street, in the City of London,
Patent Agent. "IMPROVEMENTS IN ROCK DRILLS." [A communication from
abroad by Arvid Henry Elliott, of New York, in the United States of America,
Gentleman.]
This machine is of the percussive class, and is used either with steam or com-
pressed air. Its valve is moved by air or steam, and rotates the piston, and the
cylinder is fed to the rock by hand. In this machine there are but two moveable
pieces, viz., the valve piece and the piston; there is therefore less liability to injury
and wear, the use of projections or tappets to move the valve and pawls and ratchets
for feeding and rotating being here dispensed with.
The ordinary D valve is used, but it is made circular, and has at each end a
piston turned to fit the valve box, and is provided with a guide to prevent its
turning round. The valve box has exhaust ports for the valve pistons, and these
ports are carried across and to opposite ends of the box, and lead down into the
steam cylinder through suitable openings. From this the exhaust is carried into
the main exhaust port by a groove or recess turned in the piston, and thence by
openings in the side of the cylinder.
The guide for the valve is constructed as follows:-A hole is bored through the
circular shaped D valve lengthwise, and is slotted through for a portion of the way
to receive a feather which is let into the bolt passing through the valve. This bolt
answers the several purposes of holding the valve box caps firmly to their places, of
keeping the valve in position, and of affording support to the valve, and thus
lessening its wear on the valve seat.
The valve box is supplied with rubber cushions at each end, which are protected
by steel plates, so that the valve strikes against the face of these plates, to which
the cushions are clamped, and thus prevents jamming of the rubber and breakage of
the valve from concussion.

page_text: The piston carrying the boring bit is of ordinary construction, being a long or
double piston with packing rings at each end, but it has a groove or recess turned
out in its centre for conducting the exhaust steam or air from the valve pistons into
the main exhaust port.
The upper end of the piston is bored out to receive a fluted nut, and the fluted
bar used for rotating it; this fluted bar and feed screw are made of one piece of
steel; the cylinder is carried up and down by a collar.
The screw of the piston passes through a nut fastened to the end of the tripod,
and when the screw is revolved by the crank the cylinder is carried up and down
as required, and the piston is rotated at the same time.
The tripod is adjustable, and particularly so to quarry work, its legs being
telescopic, and the back leg being hinged so as to give the angle required.
To operate the machine the air or steam is turned on, and the valve being caused
to move upwards (the exhaust from the upper end of the valve box being open) and
the valve moving upwards opens the main supply port to the lower end of the
cylinder, and at the same time freeing the exhaust from the upper end of the piston
immediately begins to rise till its groove closes the exhaust from the upper end of
the valve box, which then allows the valve to return downwards, and supply steam
or air to the upper end of the piston, and thus move it to the rock. This movement
of the piston closes the exhaust from the lower end of the valve box, and opens the
upper end, causing the valve to raise and continue the motion.