IMPROVEMENT IN ROCK DRILLS
Year: 1885

page_text: COMPLETE SPECIFICATION.
We, WILLIAM RICHARD WILLETTS, and HARRY BALL, both of Stamford,
Connecticut, United States of America, Machinests, do hereby declare the nature
of our invention for "IMPROVEMENT IN ROCK DRILLS," and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement:―
Our invention relates to that class of rock drills which are operated by steam, or
compressed air, and has for its objects to so simplify and improve their construction,
that the friction and consequent wear of the parts will be greatly reduced and a
machine produced which, while economical in cost, shall not be liable to get out of
repair, and will perform a greater amount of work and with less power than any
machine now in use.
With these ends in view we have devised the simple and novel construction
which we will now describe referring by letters to the accompanying drawings
forming part of this specification, in which-
Fig. 1, is a vertical central section of the cylinder, as on line x, x, Fig. 3.
Fig. 2, an elevation of the rear cap of the cylinder removed showing the ratchet
wheel and spring pawls.
Fig. 3, an end elevation of the cylinder showing the feeding mechanism and port
cap, the plates being indicated in dotted lines, and
Fig. 4, a horizontal central section at a right angle to Fig. 1, as on line 3, y,
Fig. 3.
Similar letters indicate the same parts in all the Figs.
A, is the cylinder having a flanged base A³, and B, the piston, the shape of which
is clearly shown in Figs. 1, and 4. B¹, is the piston rod, and C, the upper cap of
the cylinder, which is provided with a recess C¹, to accommodate a ratchet wheel O,
the function of which will presently be explained. D, is the lower cap through
which the piston rod passes. E, is a rod having spiral grooves as shown, which are
engaged by corresponding splines in the recess B³, in the piston, as will be more
fully explained. F, is the feed rod, the yoke or arm which it engages not being
shown. G, is the valve which covers the ports H, and the exhaust H. This
valve is operated by a rock shaft I, to which it is connected by an arm or rod I.
This rock shaft is journaled in a socket formed partially in projection A', on the
LPin G21

page_text: cylinder and partially in plate M, which is securely screwed or bolted to pro-
jection A¹. N, is a similar plate screwed to projection A', which covers the valve
and arm I, forming a small steam chest A, which the steam enters at A*, and then
passes to the ports.
The rock shaft 1', is provided with a cross piece L, which is acted on by pins K,
which are alternately lifted by the inclines B³, upon the piston. The action of said
inclines being to tilt or rock shaft I, which causes valve G, to pass from one port to
the other, to control the entrance of steam into the cylinder. It will of course be
understood that the drill itself is attached in any suitable manner to the piston
rod B. The rotation of the drill is accomplished by means of the spirally grooved
rod E, which engages the piston.
This rod is provided with a ratchet wheel O, rigidly secured thereto. O¹, indicates
spring actuated pawls which engage the ratchet and hold it from turning backward,
so that when the piston moves upward i.e. toward the right in Fig. 1, the piston
and piston rod turn upon the grooves of the spiral rod E, but when the piston
moves downward, rod E, and the ratchet are free to turn, so that the blow of the
drill is delivered straight forward.
Beyond the ratchet wheel, rod E, passes through a stuffing box P, of any ordinary
construction. Q, is a gear wheel, loose upon rod E, which meshes with a gear
wheel Q¹, on the feed rod F, said rod being free to rotate in the base A³, of the
cylinder. This gear is preferably tapped on a bushing Q, which is secured to the
feed rod by a spline or feather a, so that when gear Q₁, is rotated the feed rod is
carried with it. R, is a beveled friction plate or clutch which slides upon shaft E,
and is caused to rotate therewith by a spline upon the shaft engaging a groove, not
shown. R¹, is a knob which is screwed upon the end of shaft E, forcing the bevel
of plate R, against the loose gear Q, thus locking the gear to the plate and causing
it to rotate with shaft E. The operation is as follows; the power (steam or
compressed air preferably the former) is admitted to the steam chest A³, through
the pipe shown in dotted lines in Fig. 3, and will rush through one of the ports H,
shown clearly in Fig. 1. Suppose that the steam has passed into the cylinder
through the right hand port (the upper one when in operative position) as the
piston passes below the middle of the cylinder the right or upper pin K, begins to
travel up the right or upper incline on the piston. This pin acting on cross piece L,
causes sufficient rotary movement to rock shaft I, to carry valve G, over the upper
port, cutting off the entrance of steam into the cylinder above the piston, but
allowing it to enter the cylinder at the other port thus raising the piston, the steam
in the cylinder above the piston being forced out at the exhaust. The valve con-
tinually moves from one port to the other, but the exhaust is continually covered.
When the piston is at the upper end of the cylinder, the lower incline on the
piston acts on the lower pin to cut off the steam below, and to admit it above the
piston, these operations being repeated at each stroke of the piston. As the piston
moves up, rod E, having the spiral grooves, is held stationary by the pawls engaging
the ratchet wheel, this causes the piston to make a partial revolution. As the
piston descends, it in turn imparts the same amount of rotation to rod E, that said
rod imparts to the piston during the upward stroke. This movement of rod E,
carries gear Q, with it, provided of course that the latter is locked upon the rod.
Gear meshes with gear Q¹, upon the feed rod turning said rod which is screw
threaded its entire length. The mechanism for imparting rotation to the feed
rod is wholly new, and of our invention, but motion is communicated by the
feed rod to the cylinder in the ordinary manner, which we have deemed it
wholly unnecessary to illustrate, that is, the feed rod passes through a corre-
spondingly threaded opening in a yoke or arm, (not shown) projecting from
the column U. This acts of course to raise or lower the drill according to the
direction in which the feed rod is rotated. At the upper end of this rod a crank
(not shown) is always provided. This crank is used to raise the drill, or for a
hand feed when it is not desired to use the automatic feed. As stated above the

page_text: automatic feeding mechanism is connected or disconnected by means of knob R¹,
which forces the clutch plate R, into engagement with the loose gear Q, thus
locking them together. To disengage the automatic feed it is simply necessary to
loosen knob R', which in turn loosens the clutch thus leaving gear Q, loose upon
shaft E.
We do not desire to limit ourselves to the exact construction shown, as it is
obvious that the details may be varied within reasonable limits without departing
from the spirit of our invention.
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. In a rock drill the steam chest having steam and exhaust ports, in combination
with a valve adapted to slide over the exhaust and the ports, and a rock shaft
having an arm which carries said valve, and a cross piece adapted to be acted on
by pins which are alternately lifted by inclines upon the piston, whereby the ports
are alternately opened and closed.
2. The cylinder and steam chest having steam and exhaust ports, in combination
with a rock shaft held in place by cap M, and having an arm which carries a valve
adapted to slide over said ports, and a cross piece acted on by pins which are
alternately lifted by inclines on the piston, whereby the rock shaft is vibrated and
the valve carried from one port to the other to admit steam alternately above and
below the piston.
3. The piston, rod E, engaging therewith, and having a ratchet and pawls to hold
it against rotation in one direction, in combination with a gear upon the feed rod,
a loose gear upon rod E, and means, as a sliding clutch plate keyed to said rod,
whereby the loose gear, and the gear upon the feed rod may be connected or dis-
connected, substantially as and for the purpose set forth.
4. The feed rod free to rotate in the base of the cylinder and carrying a gear Q',
in combination with a recessed piston, a rod E, having spiral grooves engaging
therewith, the ratchet and pawls, a loose gear upon rod E, a sliding clutch plate
held against rotation on said rod, and a knob for forcing the clutch plate into
engagement with the loose gear, whereby the automatic feed may be connected or
disconnected.