Rotating Mechanism for Rock Drills.
Year: 1891

page_text: Date of Application, 1st June, 1891-Accepted, 4th July, 1891
COMPLETE SPECIFICATION.
Rotating Mechanism for Rock Drills.
We, HARRY BALL, of Stamford, Fairfield County, Connecticut, U.S.A.,
Machinist, and FREDERICK LENGGENHAGER, of Glenbrook, Fairfield County,
Connecticut, U.S.A., Manufacturer, do hereby declare the nature of this inven
tion, 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 operating either by steam or compressed
air, and has for its object to provide novel mechanism for rotating the piston
and piston rod to which the drill, not shown, is attached in any ordinary or
preferred manner, the effect of my present invention being to simplify the con-
struction and reduce the number of parts, thereby cheapening the cost of production
and securing at the same time durability, non liability to get out of repair, and
thoroughly effective operation in use, the construction moreover being such that
in the event of the breakage of any of the parts, the broken parts may be removed
and new ones substituted with but slight expense by any person capable of running
a rock drill, thus avoiding the necessity of going to a machine shop or stopping
the drill but for a very short time. For the sake of clearness I have omitted
from the drawing all portions of the drill except such as are necessary to clearly
illustrate the construction and operation of the rotating mechanism.
Fig. 1 is a section of the cylinder and piston, also showing the rotating
mechanism partly in elevation and partly in section;
Fig. 2, an elevation of the upper i.e. the left head of the cylinder and the plate
covering the eccentric and crescent-shaped piece, the cylinder being removed;
Fig. 3, a similar view with the covering plate removed, showing the eccentric
and crescent-shaped piece in the position they occupy during the upward movement
of the piston, the eccentric and crescent-shaped piece rotating with the grooved
rod so that the piston can move straight up;
Fig. 4, a similar view showing the position of the parts during the downward
movement of the piston, the grooved rod, eccentric and crescent-shaped piece being
locked against rotation so that the piston is compelled to rotate; and,
Fig. 5 is an elevation of the end of the piston showing the hardened steel nut
provided with lugs which engage the grooves of the rod.
1 denotes the cylinder, and 2 and 3 the heads thereof, said heads and the cylinder
proper being, in practice, clamped together by longitudinal bolts, not shown, which
pass through holes in the heads (see Figs. 2, 3 and 4). 5 denotes the piston,
and 6 the piston rod which passes through an opening in cylinder head 3, being, in
practice, ordinarily made in two parts and provided with a recess to receive
packing 7, said recess being closed by a screw cap 8 through which the piston rod
passcs. The piston is provided with a central, longitudinal opening 9 which
receives spirally grooved rod 10 freely. At the upper end of the opening in the
piston is a nut 11 which is preferably made of hardened steel and which is provided
with lugs 12 to engage the grooves in the rod. Head 2 of the cylinder is provided
with a socket 13 to receive the other end of rod 10, and with a recess 14 which is
concentric with the socket. This recess, in practice, is closed by a plate 15 which
is provided with a central opening through which the rod passes and is made the
exact diameter of the bore of the cylinder. The plate is made to fit closely and
lies partly in the bore of the cylinder and partly in a recess in head 2 adapted to
receive it. This plate acts to effectually close this end of the piston against the
passage of steam. Within the recess and secured rigidly to the rod is an
eccentric 16 which is provided with a pin 17 extending outward from its periphery
In the present
at a point slightly at one side of the longest radius of the eccentric.

page_text: instance the parts are so organized as to produce a rotation of the piston and piston
rod during the downward movement, i.e. the movement toward the right. This
requires that the pin be placed at the right of the greatest radius of the eccentric
as seen in the drawing. Should rotation of the piston and piston rod be required
during the upward movement, i.e. the movement toward the left, the pin would
require to be placed at the left of the longest radius of the eccentric as will be fully
explained. Outside of the eccentric and lying within recess 14 is a crescent-shaped
piece 18 between the ends of which is an open space in which pin 17 lics.
19 is a
notch in the inner side of the crescent-shaped piece, the object of which is to permit
said piece to yield sufficiently to allow it to be sprung into place over the eccentric.
The periphery of crescent-shaped piece 18 is concentric with recess 14 and with
rod 10, the inner line of said crescent-shaped piece corresponding with the periphery
of the eccentric.
The operation is as follows: Suppose the parts to be in the positions shown in
Figs. 1 and 3, when the upward movement, ie. the movement of the piston toward
the left of the cylinder, takes place, pin 17 will engage one end of the crescent-
shaped piece, the right end as shown in Fig. 3, and will carry said piece with it.
It will be apparent in view of the engagement of lugs 12 on the piston with the
spiral grooves of rod 10 that at each movement either the piston itself or the rod
must rotate. In the position of the parts shown in Fig. 3 the piston moves straight
up, that is without rotation, and the rod is rotated by the engagement of the lugs
with the spiral grooves carrying the eccentric with it, and the latter, through the
engagement of the pin with the end of the crescent-shaped piece, carries the latter
also, the rod, eccentric and crescent-shaped piece turning freely in recess 14. The
instant the downward movement of the piston, i.e. the movement toward the right,
commences, the spirally grooved rod is necessarily turned in the opposite direction.
This moves the eccentric in the opposite direction, moving the pin away from the
end of the crescent-shaped piece with which it has been in engagement. The effect
of this reverse movement of the eccentric is to carry the point in the periphery of
the eccentric having the longest radius against the inner side of the crescent-shaped
piece, springing the latter outward and causing it to be locked tightly in recess 14
by friction. In fact, the rotary movement of the grooved rod in this direction is
stopped almost instantly, so that as the piston moves downward it is necessarily
rotated through the engagement of the lugs with the grooves in the rod.
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 :
1. In a rock drill, a piston having a longitudinal recess, and lugs extending into
said recess, in combination with a spirally grooved rod which is adapted to enter
the recess in the piston and is engaged by the lugs, an eccentric rigidly secured to
said rod and having a pin projecting from its periphery at one side of the longest
radius thereof, and a crescent-shaped piece lying in a recess outside of the eccentric,
one end of said piece in use being engaged by the pin so that when the piston is
moved in one direction it will rotate the rod, eccentric and crescent-shaped piece,
and when moved in the opposite direction the longest radius of the eccentric will
be forced against the crescent-shaped piece, springing the latter outward against
the wall of the recess, thereby locking the eccentric and rod against rotation and
causing a rotary movement of the piston.
2. The combination with the piston having longitudinal opening 9, and lugs 12,
of spirally grooved rod 10 engaging said opening and lugs and having rigidly
secured thereto an eccentric with a pin extending from its periphery at a point at
one side of the longest radius, and a crescent-shaped piece lying outside of the
eccentric one of whose ends is engaged by the pin when the piston is moved in one
direction, substantially as described.
3. The piston having an opening 9 and Ings. 12, the piston rod, and the cylinder
having a head 3 through which the piston rod slides, and a head 2 having a

page_text: socket 13 and recess 14, in combination with a spirally grooved rod one end of
which engages the lugs and opening in the piston, the other lying in socket 13,
and an eccentric lying in recess 14, said eccentric having a pin 17 at one side of
the longest radius, and a crescent-shaped piece 18 lying in said recess outside of the
eccentric.
4. The cylinder, one of whose heads is provided with a socket 13 and recess 14,
and the piston having a longitudinal opening, and a nut at the outer end thereof
having inwardly projecting lugs, in combination with a rod having spiral grooves
adapted to be engaged by the lugs and whose opposite end rests in the socket, an
eccentric in the recess which is rigidly secured to the rod and is provided with a
pin 17, and a crescent-shaped piece lying in the recess outside of the eccentric, said
parts acting as described and for the purpose set forth.
Dated this 18th day of May 1891.
HARRY BALL.
FREDERICK LENGGENHAGER.