Improvements in the Feed Mechanism of Percussive Rock Drills.
Year: 1898

page_text: Date of Application, 6th Aug.; 1898
Complete Specification Left. 1st May. 1899-Accepted. 10th June 1800
PROVISIONAL SPECIFICATION.
-Improvements in the Feed Mechanism of Percussive Rock Drills.
We, ALBERT WILLIAMS DAW, and ZACHARIAS WILLIAMS Daw, both of Mansion
House Chambers, 11, Queen Victoria Street, in the City of London, Mining
Engineers, do hereby declare the nature of this invention to be as follows:-
:-
This invention relates 1st to an automatic feed mechanism for rock drills, and
2nd to means for preventing the rotation of the nut through which the feed screw
passes when the latter is rotated for the purpose of moving the drill back along
the cradle after the full forward feed has been attained.
In carrying out the first part of our invention we provide a valve mounted in
a small cylinder at the forward end of the main cylinder of the rock drill, such
valve being so placed that it shall be acted on by the main piston when the
latter attains its full forward stroke.
Any suitable form of valve may be employed for this purpose, the effect of the
operation of same by the main piston being that a passage shall be opened from
the main supply of compressed air or other actuating medium to the small cylinder
in which the valve is mounted so that such air can pass through the valve to
the back of a piston mounted in a second small cylinder conveniently situated in
relation to the ratchet secured to the feed nut. The tail rod of the piston in this
second small cylinder carries a pawl working in connection with such ratchet, so
that on the piston being operated this pawl will actuate the ratchet and so rotate
the feed nut and feed the drill forward along the feed screw, which at this time
is held stationary by a pin or other suitable means.
The valve which opens the supply to the second small cylinder above referred
to is arranged to close by a spring or by the pressure of the compressed air or
other actuating medium acting upon its upper surface, whilst the main piston is
making its backward stroke after opening such valve.
Ports are provided at suitable positions in the second small cylinder to allow
the compressed air or other actuating medium to escape after actuating the
piston, which latter is preferably acted upon by a spring to return it to its normal
position after it has been operated as above described, such ports being opened
by the upward travel of the piston.
The second part of our invention consists in the provision of suitable means for
preventing the nut through which the feed screw works from rotating with the
latter when the screw (after having first been rendered capable of being rotated)
is revolved by hand so as to move the drill back in its cradle along the screw after
the full forward feed has been attained. This is effected by exerting pressure
upon the feed nut by any suitable means, such as by providing the nut with a
collar the periphery of which is milled, and on which periphery one or more
spring arms are caused to bear so that the friction thus obtained will prevent the
nut from turning with the feed screw.
Dated this 6th day of August 1898.

page_text: Cm of rercussive Rock Drills.
We, ALBERT WILLIAMS DAW, and ZACHARIAS WILLIAMS DAW, both of Mansion
House Chambers, 11, Queen Victoria Street, in the City of London, Mining
Engineers, 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:-
This invention relates 1st to an automatic feed mechanism for rock drills, and
2nd to means for preventing the rotation of the nut through which the feed screw
passes when the latter is rotated for the purpose of moving the drill back along
the cradle after the full forward feed has been attained.
In carrying out the first part of our invention we provide a valve mounted in
a small cylinder at the forward end of the main cylinder of the rock drill, such
valve being so placed that it shall be acted on by the main piston when the
latter attains its full forward stroke.
Any suitable form of valve may be employed for this purpose, the effect of the
operation of same by the main piston being that a passage shall be opened from
the main supply of compressed air or other actuating medium to the small cylinder
in which the valve is mounted so that such air can pass through the valve to
the back of a piston mounted in a second small cylinder conveniently situated in
relation to the ratchet secured to the feed nut. The tail rod of the piston in this
second small cylinder carries a pawl working in connection with such ratchet, so
that on the piston being operated this pawl will actuate the ratchet and so rotate
the feed nut and feed the drill forward along the feed screw, which at this time
is held stationary by a pin or other suitable means.
The valve which opens the supply to the second small cylinder above referred
to is arranged to close by a spring or by the pressure of the compressed air or
other actuating medium acting upon its upper surface, whilst the main piston is
making its backward stroke after opening such valve.
Ports are provided at suitable positions in the second small cylinder to allow
the compressed air or other actuating medium to escape after actuating the
piston, which latter is preferably acted upon by a spring to return it to its normal
position after it has been operated as above described, such ports being opened
by the upward travel of the piston.
The second part of our invention consists in the provision of suitable means for
preventing the nut through which the feed screw works from rotating with the
latter when the screw (after having first been rendered capable of being rotated)
is revolved by hand so as to move the drill back in its cradle along the screw after
the full forward feed has been attained. This is effected by exerting pressure
upon the feed nut by any suitable means, such as by providing the nut with a
collar the periphery of which is milled, and on which periphery one or more
spring arms are caused to bear so that the friction thus obtained will prevent the
nut from turning with the feed screw.
But in order that our invention may be fully understood we will now proceed to
describe same by the aid of the accompanying drawings, in which
Fig. 1 is a side elevation (partly in section) of a rock drill embodying such
invention,
Fig. 2 a plan view thereof,
Fig. 3 a transverse section on the line 3-3 of Fig. 2,
Fig. 4 a transverse section on the line 4-4 of Fig. 2,
Fig. 5 a horizontal section showing a suitable manner of fixing the feed screw,
and
4

page_text: Fig. 6 an end view of Fig. 5.
Similar letters of reference are employed to indicate corresponding parts in all
the figures.
A is the small cylinder at the forward end of the main cylinder Z and in which
valve B is mounted, the top of such cylinder A being permanently open to the
supply of compressed air or other actuating medium through the passage C. The
lower end of the stem of valve B projects slightly inside the main cylinder Zi,
so that when the main piston attains its full stroke within the latter it will raise
valve B from its seat and permit the compressed air to pass below same.
Towards its lower end the cylinder A is connected by a passage 1) to another
small cylinder E at the rear end of main cylinder Z, so that when valve B is
raised compressed air can pass into cylinder E below the piston F mounted therein.
The end of the rod of piston F is formed as a pawl G which engages the ratchet
wheel H of the feed nut I. A spring K acts upon piston F tending to keep it in
its downward or forward position, but when compressed air is admitted to
cylinder E below piston F, the pressure of same overcomes the force of such
spring K and moves the piston upwards, whereby the pawl G formed on the rod
of the latter will cause the ratchet wheel H to rotate a certain distance, thus
actuating the feed nut I and so feeding the drill along the feed screw L, the
latter being held stationary by suitable means, such as by the pin M passing
through it and the frame of the drill, as shown in Figs. 5 and 6.
After opening the valve B and so allowing air to pass into cylinder E as above
described, the pressure of the main supply of air in cylinder A closes valve B
during the backward stroke of the main piston, and so shuts off the air from
cylinder E, and spring K will force piston F downward again, the pawl G
slipping over the teeth of ratchet wheel H. But in the meantime the feed of the
drill will have taken place and the main piston will not attain its full forward
stroke again until a further feed is required, so that until then the valve B will
not be opened and consequently no air will pass into cylinder E and therefore
the feed mechanism will remain inoperative.
The operation described is repeated as soon as a further feed of the drill is
necessary.
Ports e are formed in cylinder E to allow the compressed air to escape from
below piston F after having raised the latter, such ports being opened by the
upward travel of the piston.
A spring might be used to close or to assist in closing the valve B in cylinder A.
When the full forward feed has been attained in order to return the drill to the
other end of the feed screw Lagain, the latter is released from the frame of the
drill by removing pin M and then rotating such screw by hand by means of a
crank in the ordinary manner, and in order to prevent the feed nut I from
rotating with the screw we form a collar M upon the nut, the periphery of such
collar preferably being milled, and by means of spring arms N (or other suitable
means we exert sufficient pressure thereon to overcome the friction between the
feed screw and the nut, so that the latter will remain stationary and the drill will
consequently be moved back along the screw. It will be understood that the
pressure upon the feed nut must not be sufficiently great as to interfere with its
free rotation upon the screw when the latter is held stationary during the forward
feed of the drill.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim is;-
1. The improved automatic feed for rock drills consisting in a valve operated
by the main piston of the drill and controlling the supply of compressed air or
other actuating medium to a cylinder in which is mounted a piston whose rod
carries a pawl engaging the teeth of a ratchet wheel secured to the feed nut, sub-
stantially as specified.

page_text: 2. The means for preventing the feed nut of rock drills from rotating when the
feed screw is being revolved for the purpose of moving the drill back along said
screw, such means consisting in forming the nut with a collar and exerting suffi-
cient pressure thereon to overcome the friction between the feed nut and screw,
substantially as specified.
3. The combination of the improvements in rock drills set forth in the two
preceding claims, substantially as described and as shown in the accompanying
drawings.