An Improved Valve for Rock Drills.
Year: 1891

page_text: Date of Application, 3rd Feb., 1891-Accepted, 14th Mar., 1891
COMPLETE SPECIFICATION.
An Improved Valve for Rock Drills.
I, THOMAS EDWIN BICKLE, of the firm of Bickle and Company, of Great
Western Docks, Plymouth, in the County of Devon, Engineers and Iron Ship-
builders, 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:-
My invention relates to rock drills of the percussive type worked by compressed
air or other fluid pressure and it has special reference to a particular construction
of the valve whereby it is actuated by active air or other fluid pressure and exhaust
without the intervention of cams, tappets or other mechanical contrivances. For
this purpose the valve is constructed in the form of a piston having two annular
grooves and reciprocating in a valve box to which the compressed air or other
fluid is admitted through two ports. The valve box has three other ports on the
opposite side, two of which lead to the respective ends of the main cylinder, and the
third to the atmosphere. These ports are alternately opened and closed by the
movement of the valve, and the active air or fluid passes into and exhausts
from the two ends of the main cylinder alternately thereby imparting the
required reciprocating movement to the main piston and to the boring bit fixed
thereto.
The valve motion is produced by allowing live compressed air or other fluid to
leak into the recesses or chambers at the ends of the piston valve, these two
recesses are in communication with the atmosphere by means of two small holes or
ports which are alternately opened and closed by the intervention of the moving
piston in the main cylinder, the active pressure accumulating at one end of the
valve piston and exhausting freely at the other end so that the valve shoots over
into its proper position and effects continuously the necessary change of direction
of the movement of the main piston to which the boring bit is attached.
The annexed drawing represents so much of a rock drill as is necessary to enable
my invention to be understood.
Figure 1 is a longitudinal section and
Figure 2 a transverse section.
As
a is the main cylinder, b, is the main piston to the rod of which the boring
bit is attached. This piston has at its middle a neck or part of smaller
diameter. d, d is the valve which is in the form of a piston and has two
annular grooves e, f. The valve reciprocates in a box y to which the compressed
air or other motive fluid which arrives at his admitted through two ports i, k. On
the opposite side of the valve box g are three other ports 1, m, n. The
ports 1m communicate respectively by passages p. 7 with the two ends of the
main cylinder a, and the other port n communicates with the atmosphere.
the valve d reciprocates in the box g it puts the two ports i and alternately
by means of the grooves e, f in communication with the corresponding ports 1 and m
and thereby admits the compressed air alternately to the two ends of the main
cylinder a, and it also puts these ports 1, m alternately in communication with the
exhaust port n, so that the ends of the main cylinder are alternately exhausted.
The reciprocating motion of the piston valve d is obtained by the compressed air
leaking alternately through the two restricted passages, into the chambers or
recesses t, u at the respective ends of the valve. These two chambers t, u are in
communication with the atmosphere by means of two small ports v, w leading to
the main cylinder and two openings, in the side of this cylinder. The
ports and to and the openings and are alternately opened and closed by the
main piston ; that is to say, each of the ports v, w is opened and put into

page_text: communication with the atmosphere through the opening or in the side of the main
cylinder when the neck or part c of the main piston comes opposite such port and
opening. The compressed air or motive fluid accumulates in one or other of the
recesses t, u and exhausts freely from the other, the action being alternate so that
the piston valve is shot over and effects the necessary changes of movement of the
main piston b.
Il
In the position of the parts shown in the drawings the port i is in communication
with the port and passage p and the main piston has just completed its stroke to
the right. The right hand end of the main piston has just exhausted through the
passage port m, and port n into the atmosphere. The compressed air is leaking
through the passage into the chamber t, and the chamber has already exhausted
through the port and neck c of the main piston and through the opening into
the atmosphere. The compressed air entering the chamber t will now cause the
valve d to shoot over so as to admit compressed air through the port k, port m, and
passage to the right hand end of the main cylinder and put the left hand end in
communication with the atmosphere through the passage p, port 1, and port n. During
the stroke of the main piston which will now take place the chamber t will
exhaust through the port and neck c of the main piston and through the
opening a into the atmosphere.
The other portions of the rock drill are of ordinary construction and therefore
require no explanation.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what I
claim is
A valve for rock drills constructed substantially as hereinbefore described.
bruary 1891.
J. C. MEWBURN,
55 & 56, Chancery Lane, London, Patent Agent.