Improved Valve for Rock Drills.
Year: 1893

page_text: Date of Application, 14th Mar., 1893
Complete Specification Left, 4th July 1893-Accepted, 19th Aug.. 1893
PROVISIONAL SPECIFICATION.
Improved Valve for Rock Drills.
WILFRED JONES 35 Queen Victoria Street London E.C. Engineer do hereby
declare the nature of this invention to be as follows:-
My improvement relates to valves of rock drills of a percussive type.
The valve is made of steel or other suitable material, cylindrical in form, its
extreme length being nearly equal to that of the rock drill cylinder, fitted in a
valve box with a cylindrical bore. The valve is provided at each end with a piston to
actuate the valve, & prevent the passage of air, each of the said pistons being provided
with air passages disposed in a radial form, which corresponding with the ports in
the ends of the valve box, allow the passage of air for actuating the main piston.
By this form, economy of air (or other motive power) is secured, as the exhaust
from the main cylinder, takes place over the end of the piston valve, and all long
passages are thus avoided, & the valve can be actuated on the well known leakage
system.
Deted this 13th der of March 1803
WILFRED JONES.
COMPLETE SPECIFICATION.
Improved Valve for Rock Drills.
I, WILFRED JONES of 35 Queen Victoria Street, London, E.C. Engineer 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 the drill is actuated by compressed air or other motor fluid
and exhausts without the intervention of cams, tappets or other mechanical con-
trivances. For this purpose the valve is constructed in the form of a double piston
with rod or tube connecting the two pistons, its extreme length being nearly equal
to that of the rock drill cylinder. The valve is fitted in a valve box of cylindrical
bore and is provided with air passages corresponding with the ports in the ends of
the valve box; these ports are alternately opened and closed by the movement of
the valve, and the compressed air or other motor 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 motion of the valve is effected by allowing the compressed air or other motor
fluid to leak into the recesses or chambers at the end of the piston valve; these two
recesses are in communication with the atmosphere by means of small holes or ports
which are alternately opened and closed by the intervention of the moving piston
in the main cylinder. The fluid pressure accumulates at one end of the valve
piston and exhausts 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
inovement of the main piston to which the boring bit is attached.
The annexed drawings represent so much of a rock drill as is necessary to enable
my invention to be understood, Figure 1 is a longitudinal section, Figure 2 a
transverse section.
A is the main cylinder and B B the main piston to the rod of which the boring
bit is attached; this piston has at its middle a neck or part C of smaller diameter.

page_text: DD is the valve which is in the form of a double piston or two pistons connected
by a rod E; each of these pistons has air passages or grooves R R. The valve
reciprocates in the box F to which the compressed air or other motor fluid is
admitted through either of the ports GG. On the cylinder side of the valve box F
are two ports H and I. one at each end of the main cylinder A. These ports H I
communicate respectively with the two ends of the main cylinder A and other
ports J K communicate with the atmosphere. As the valve D D reciprocates in
the box F it admits the compressed air or other fluid alternately to the two ends of
the main cylinder A through the ports H and I respectively, and it also puts the
ports H and I alternately through the intermediation of the passages R R in the
respective ends of the piston valve in communication with the exhaust ports J K
so that the ends of the main cylinder are alternately exhausted. The reciprocating
motion of the piston valve D D is obtained by the compressed air leaking alternately
through restricted passages (not shown) into the chambers or recesses L M at the
respective ends of the valve. These two chambers are in communication with
the atmosphere by means of, first, the two small ports NO leading to the main
cylinder A and then two openings PQ in the side of this cylinder leading into the
atmosphere. The ports NO and the openings P Q are alternately opened and
closed by the main piston B B, that is to say, each of the ports N and O is opened
and put into communication with the atmosphere through the corresponding
opening P or Q in the side of the main cylinder A when the neck or part of the
main piston comes opposite such port and such opening. The compressed air or
motor fluid accumulates in one or other of the recesses L M and exhausts freely
from the other, the action being alternate so that the piston valve is shot over and
thereby effects the necessary changes of movement of the piston B B. In the
position of the parts shown in the drawings the port I is in communication with the
right hand end of the main cylinder, the left hand end of the main cylinder has
just exhausted through the port H, valve piston passage R, and port J, into the
atmosphere. The compressed air is leaking through the restricted passage already
described into the right hand chamber M of the valve box, the left hand chamber L
has already exhausted through the port N, piston neck C, and openings P, into the
atmosphere. The compressed air entering the chamber M will cause the valve D D
to shoot over so as to admit compressed air through the port H to the left hand
end of the main cylinder so as to put the right hand end in communication with the
atmosphere through the port 1, valve piston passage R, and port K. During the
stroke of the main piston which will now take place the right hand chamber M will
exhaust through the port O, neck (of the main piston, and the opening Q, 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 inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :--
A valve for rock drills constructed and working substantially as hereinbefore
described.
Dated this 30th day of June 1893.
J. C. MEWBURN,
55 & 56, Chancery Lane, London, Chartered Patent Agent.