IMPROVEMENTS IN ROCK DRILLS AND OTHER LIKE MACHINES
Year: 1877

page_text: LETTERS PATENT to Auguste Alexandre Goubert, of the City, County, and
State of New York, Mechanical Engineer, and Nathaniel Waterman Pratt, of
Brooklyn, King's County, New York, United States of America, Mechanical
Engineer, for the Invention of "IMPROVEMENTS IN ROCK DRILLS AND OTHER
LIKE MACHINES.”
Sealed the 15th September 1877, and dated the 26th July 1877.
COMPLETE SPECIFICATION filed by the said Auguste Alexandre Goubert
and Nathaniel Waterman Pratt, at the Office of the Commissioners of Patents
on the 26th July 1877.
AUGUSTE ALEXANDRE GOUBERT, of the City, County, and State of New York,
Mechanical Engineer, and NATHANIEL WATERMAN PRATT, of Brooklyn, King's
County, New York, United States of America, Mechanical Engineer. "IMPROVE
MENTS IN ROCK DRILLS AND OTHER LIKE MACHINES."
Our improvements relate to that class of machines in which a tool stock is
reciprocated by the direct action of steam or compressed air. In machines of this
kind the effective work is done by the stroke of the piston in one direction, and the
return stroke of the piston is only required to withdraw the working parts into
suitable position to enable them to repeat the working blow.
Our improvements consist primarily in effecting the reciprocation of a tool stock
by connecting it with a piston having a variable area upon its opposite sides, the
side having the smaller area being that upon which live steam acts for the purpose
of delivering the working blow, while the side of the piston having the larger area
is acted upon to withdraw the tool stock and tool from its work, such withdrawal
being effected by the operation of a suitable valve, valve passages, and ports,
whereby the steam which has effected the working stroke is conducted or whipped
around to the opposite side of the piston, where it expands and effects the return
stroke of the piston by reason of the greater area which that side of the piston
presents. The steam which has thus effected both strokes of the piston is dis-
charged from the cylinder by the next working stroke, hence we exhaust at com-
paratively low pressure and thus economize in the use of motive power.
Another feature of our Invention consists of an automatic friction feed, the

page_text: operation of which is governed by the extent of the advance of the tool at each
working blow; the feed mechanism being set preparatory to forming its function by
the last part of the motion of the tool stock.
The accompanying Drawings represent our improvements as applied to a rock
drill and are as follows:-
Figure 1 is an elevation of the rock drill mounted upon an ordinary tripod;
Figure 2 is a transverse section through the line x, x; on Figure 1; Figure 3 is a
central longitudinal section through the line y, y, on Figure 2.
Figure 4 is a transverse section of the inlet valve to the steam chest, showing the
principal steam port wide open; also showing a small passage on each side of the
principal steam port for conducting steam into the extreme ends of the cylinder
in order to start the piston in case the sliding valve should not be in proper position
for that purpose; Figure 5 is a central longitudinal section through the line 2, 2, on
Figure 2.
Figure 6 is a central longitudinal section showing a modification in the form of
the rock drill, which consists in inserting the reciprocating tool stock in the centre
of a double trunk piston.
Figure 7 is an elevation of the tripod for supporting the drill cylinder; Figure 8
is a transverse vertical section of the head of the tripod through the line 1, 1, on
Figure 7; Figure 9 is a longitudinal vertical section of the head of the tripod
through the line 2, 2, on Figure 8.
Figure 10 is a side view of the upper end of one of the side legs of the tripod
showing the mode of clamping the side leg to the head.
Figure 11 is a central longitudinal section of one of the tripod legs, showing the
clamp by which the lower joint is prevented from moving, and also showing the
weight and the method of fastening the weight to the lower joint; Figure 12 is a
transverse section of one of the legs through the line 3, 3, on Figure 11; Figure 13
is a transverse section of the weight and tripod leg through the line 4, 4, on
Figure 11.
The Drawings represent a steam cylinder A provided with the usual ports a, a¹,
at either end and containing the trunk piston B. A slide valve C is so arranged
with reference to the steam chest D, that in the position which it occupies pre-
paratory to the working stroke of the drill, it admits steam from the steam chest
into the annular space E, surrounding the trunk in the upper part of the cylinder.
In its opposite position the valve opens the ports e and f, and thus establishes com-
munication through the expansion passage e between the annular space E in the
upper part of the cylinder and the space F in front of the piston in the lower end
of the cylinder; at the same time the valve closes the port d of the steam chest.
In case of an excessive penetration of the drill the piston may overrun, and the
valve being thus thrust beyond the point where it closes, the port d will open com-
munication between the steam chest and the space F, and thus admit live steam in
front of the piston to act as a cushion therefor. The instant however that the
return movement of the piston commences the valve springs back, closing the steam
port d and holding the ports a and a wide open. This action of the valve in
following back the tappet by which it is moved is effected by means of the spiral
spring which surrounds the valve stem, and is contained within the cylindrical
chamber g¹ between the two movable disks g² and g³. The valve stem is provided with
the two adjustable collars c¹ and c², which respectively bear upon the discs g² and g³
when the valve has completed its motion in either direction. If the valve slides too
far in either direction, one of the collars on the stem pushes the disk with which it
is in contact into the cylinder and thus compresses the spring. As soon as the
valve stem is relieved from the pressure of the tappet by which it has been moved,
the spring throws out the disk which has been pressed in, and thus acting upon the
collar carries the valve back into its appropriate position at either end as the case
may be. The valve is thus provided with a double-acting yielding spring stop.
As rock drills may penetrate more or less at different blows, according to the
varying hardness of the rock in which they are worked, the forward movement of

page_text: the piston and consequently the movement of the valve is determined by the point
at which the drill brings up on the rock. It is necessary to provide valve gear
which is capable of effective operation under the circumstance of a varying stroke of
the piston. In our machine the working stroke of the drill is effected by live steam
acting in the trunk end of the cylinder, and the return stroke is effected by the
same steam acting expansively through the open ports connecting the opposite ends
of the cylinder upon the greater area of the face of the piston.
Although it may happen that the valve will be thrown too far by the downward
stroke of the piston owing to the excessive penetration of the drill, and the steam
port & will thus be opened, we are enabled to close that port as soon as the return
stroke commences, and thus prevent the waste of steam on the return stroke of the
piston. While live steam is being admitted into the trunk end of the cylinder the
exhaust port a² is open, and we thus exhaust at low pressure because we have only
introduced live steam enough to fill the annular space E, and that quantity of steam,
by passing around into the space F in front of the piston has expanded during the
back stroke of the piston.
To facilitate the starting of the piston in case the slide valve is not in proper
position when steam is first let on, we arrange in connection with our inlet valve T
two small passages, e and f, on either side of the principal steam port t; by turning
the valve plug T¹ in either direction live steam may be admitted directly into the
ends of the cylinder through the passages e and f respectively, and the piston being
thus started, the valve plug is turned to the position shewn in Figure 4, and
thence forward; the machine will be operated by the slide valve as already
described.
The outer end of the trunk piston is secured to the cross head B¹, the pro-
jecting portion of which constitutes the nut I, which engages the male thread i on
the upper portion of the tool stock or drill carrier bar K. The lower end of the
nut I is secured to the tube I¹, which affords a bearing for the carrier bar K. The
tube I¹ reciprocates with the nut and is supported by the bearing 12 on the side of
the cylinder A. The tappet c projects laterally from the nut I and is perforated to
receive the valve stem c³. On the side opposite the tappet another arm L projects
laterally from the cross head and is perforated to receive the rock shaft M. The
arm M is formed into two spiral wedges, and I, which are respectively on oppo-
site sides of the rock shaft M, and are inclined in opposite directions. The wedges
reciprocate with the drill bar, and act simultaneously upon the shell cam N, which
is affixed to the rock shaft M. This cam is composed of two pieces, n and n¹, the
ends of which respectively form tight fitting collars, which are affixed to the rock
shaft by the pins or set screws, n, and n. Between the collars the cam forms a
tubular shell surrounding the rock shaft M, and having upon its opposite sides slots
in which the reciprocating wedges and travel. The shell cam is made in two
pieces to promote convenience in putting the machine together.
The operation of the wedges upon the cam is as follows:-During the upward
stroke of the piston the wedge engages the longer spirally inclined edge m of the
slot on one side of the rock shaft, and the wedge engages the corresponding
incline m¹ on the opposite side of the rock shaft. The action of the wedges upon
the longer incline effects a partial rotation of the rock shaft in the direction shown
by the arrow in Figure 2. The first effect of the return motion of the wedges isto
withdraw them from contact with the inclines m and m¹, and they produce no
effect upon the rock shaft until near the completion of the downward stroke of the
piston when the opposite sides of the wedges and engage the shorter spirally
inclined edges of the slots m² and m³ respectively. The action of the wedges
upon the shorter inclines effects a partial rotation of the rock shaft in the direction
opposite to the arrow in Figure 2, and the extent of this rotation is determined by
the distance to which the wedges travel in a downward direction, that distance
being fixed by the point where the tool brings up on its work. The upper end of
the rock shaft M is provided with the arm O, which is connected by means of the
short pitman O¹ with the loose collars O2, which are hung on the hub of the feed

page_text: wheel P on opposite sides of the feed wheel respectively. The adjustable pawl p is
pivoted between the projecting wings o³ of the collars 0%. The periphery of the
feed wheel has a V groove in which the face of the pawl fits; when moving in one
direction the pawl slides freely in the V groove; when moving in the opposite
direction the pawl binds in the groove and hence rotates the feed wheel in the
direction shown by the arrow in Figure 2.
The feed-wheel hub is a short hollow shaft having its bearings in the lateral
projection a from the shell frame a¹ to the opposite end of which the cylinder is
bolted. The interior of the shell a¹ forms a guide for the cross head upon the
outer end of the piston rod; the outer end of the feed-wheel shaft is provided with
a fixed collar P¹ which is formed into a wheel for convenience of turning the feed
wheel by hand. The interior of the hub of the feed wheel is provided with fixed
keys Q, which loosely engage the longitudinal key seats Q', in the upper portion of
the carrier bar K. It will thus be seen that in the latter part of the downward
motion of the piston the action of the wedges upon the short inclines of the shell
cam rocks the shaft M, and swings back the pawl p to a greater or less distance,
which is determined by the point where the tool brings up on its work. In the
upward stroke of the piston, by the contrary action of the wedges upon the shell
cam and rock shaft, the pawl forces the feed wheel to rotate, which by means of its
keyed connection with the drill carrier bar causes that to rotate and be thereby fed
forward longitudinally by the engagement of its male screw thread with the female
thread in the nut 02 Thus the amount of work done in one blow governs the
action of the feed mechanisin preparatory to the next blow.
Our chuck for holding the drill consists of the cylindrical recess R in the lower
end of the drill carrier bar, the wedge keys 1, 2, 7, loosely contained in the longi-
tudinal slots r¹, r, r, in that part of the drill carrier bar which constitutes the
shell of the recess R, and the conical collar S; by pushing up the collar S we are
enabled to insert the stem of the drill in the cylindrical recess R, and we hold the
drill by them driving down the collar S, and thereby wedging the keys r, r. 1º,
between the interior of the collar and the stem of the drill.
Our Invention includes certain improvements in the construction of the tripod
for supporting the cylinder. These improvements consist,
First. In the mode of connecting the upper ends of the three tripod legs.
And, Secondly. In a clamp and key which perform the double function of holding
the lower joint of the telescopic leg in the position to which it is extended, and also
of preventing the turning of that joint in the hollow upper joint, in which it is
inserted.
Thirdly. In supporting the weights on the lower joints of the tripod by means of
adjustable collars provided with lateral stems adapted to receive sets screws, the
points of which enter longitudinal grooves or key seats in the lower joints, the
weights being recessed and bored to admit the collar and its stem and allow access
to the set screw, so that the collar may be adjusted without removing the weight
from the leg.
By referring to Figures 7, 8, 9, 10, 11, 12, and 13 it will be seen that our tripod
consists of a central leg forked at its upper end to afford two bearings for the
transverse shaft U, which terminates at either end in the balls U¹, U¹. Each of the
two side legs of the tripod is secured at its upper end to the jointed clamp U², which
embraces one of the balls U¹, and is made to bind thereon by means of the trans-
verse bolt and nut U³.
The drill cylinder has a trunnion which fits into the recess U* formed in a boss
projecting laterally from the clamp U5. The clamp Us embraces the central portion
of the shaft U, and is secured thereupon by means of the clamp bolt and nut U
The shaft U is provided with an annular recess U7 to admit a portion of the bolt Uº.
The trunnion of the cylinder is held in the recess U by the screw bolt U8.
Each of the tripod legs is telescopic, the upper section being tubular to receive
the lower sliding section. The lower section or joint V of each leg is provided
with a longitudinal key seat V¹. The adjustable clamp V2 is slipped over the lower

page_text: end Vs of the upper joint of the leg. The lower part V³ of the upper joint is slit
longitudinally to permit of its being sprung against the lower joint when the clamp
V is tightened, which is effected by means of the transverse bolt and nut V*, the
object of the clamping mechanism being to hold the lower joint at any desired point
to which it has been extended. The clamp V2 is held in position upon the lower
end V3 of the upper section of the leg by means of the key V³, which is provided
with two laterally projecting lugs, v³, which pass through the shell of the tube
and through the clamp, and are provided exteriorly with screw threads to receive
the nuts, by means of which the key is firmly secured in place. When the
clamp V is tightened by means of the bolt and nut V³, the key V³ is pressed firmly
into the key seat V, and thus holds the lower joint firmly in position. When the
clamp U2 is loosened, the key still projects into the longitudinal groove or key
seat V¹, and prevents the lower joint from turning. The object of this is to prevent
the larger portion of the weights which are affixed to the lower joints from swinging
toward the interior of the tripod, where they would interfere with each other if the
legs of the tripod were set close together.
The weights W, W, W, are supported upon the lower joint by means of the
adjustable collar W₁, provided with the laterally projecting stem W2, which is
tapped out to receive the set screw W³, the conical point of which W* enters the
longitudinal groove V2 in the lower joint V. The weights are slotted longitudinally
to receive the leg, and recessed, as shown at W5, to receive the collar W¹. A hole W
is bored transversely through the weight to receive the stem W2 of the collar, and
also to allow access to the set screw, so that the collar may be loosened and the
weight moved up or down on the lower joint V without being removed from the
joint.
The adjustable collar is prevented from turning upon the leg by the set screw
which projects into the groove V2, and the stem W2 of the collar, which is received
in the hole Wo in the weight, prevents the weight from turning.
In the modification of our Invention shown in Figure 6 the tool stock is carried
through the center of a double trunk piston. The large end of the trunk constitutes
the nut for engaging the screw thread on the tool stock, and the smaller trunk on
the opposite end of the piston is the guide for the tool stock. The feeding mechanism
in this case is the same as that shown in Figure 1.
The nut or end portion of the larger trunk has two laterally projecting arms p
and p', whieh work through slots in the shell of the chamber adjoining the cylinder.
One of these arms p is the tappet for operating the valve, and the other arm p¹ is
for carrying wedges which operate the feed cam.
The valve is of the same character as that previously described, and by its opera-
tion live steam is admitted into the space E¹, wherein it acts to effect the working
blow of the tool, and from which it is whipped around by the operation of the valve,
as before, into the space F¹ in front of the piston, and therein, by its expansion,
effects the return stroke of the piston and the withdrawal of the tool from its work.
It will be seen that in this modification of our Invention we have a double trunk
piston, or, in other words, a piston with a large trunk on one side, the end of which
constitutes the nut for acting on the tool stock, and a small trunk upon the opposite
side of the piston, which acts as the guide for the tool stock.
We claim as our Invention in a rock drill substantially such as described,-
First. A trunked piston and suitable tappets reciprocating therewith in combina-
tion with a valve operated by the tappets, and adapted to admit live steam to the
upper and smaller area of the piston during the whole of the working stroke, and at
the conclusion of the working stroke to open communication between the opposite
ends of the cylinder, and thus admit the steam which has effected the working
stroke to the lower and larger area of the piston for the purpose of effecting the
return stroke.
Secondly. A reciprocating valve, the stem of which is provided with shoulders or
collars in combination with a reciprocating tappet and with a double-acting yielding
spring stop, two of the collars acting to receive and transmit to the valve stem the

page_text: reciprocating motion of the actuating tappet, and similar collars serving to receive
and transmit to the valve stem the thrust of the yielding spring stop, whereby, if
the valve overruns, it is made to follow back the actuating tappet on the reverse
stroke, and return to one of its two normal positions, where it holds the ports
respectively wide open.
Thirdly. In combination with a steam cylinder provided with a trunk piston,
substantially such as described, wherein the live steam which is used for effecting
the working stroke is whipped around to the opposite side of the piston to effect by
its expansion the return stroke, the reciprocating valve c and the ports d and f,
whereby, when the piston overruns, the valve motion is prolonged sufficiently to
open the live steam port, and thus admit live steam in front of the piston to form
a steam cushion to arrest the blow of the piston, and whereby the live steam port is
closed immediately after the commencement of the return stroke of the piston.
Fourthly. The feeding cam N, composed of the two parts n¹¹ and n²², keyed to
the opposite ends of the rock shaft M, substantially as shown and for the purpose
set forth.
Fifthly. A reciprocating tool stock provided with a male screw thread which
engages a reciprocating nut, whereby the tool stock is fed longitudinally by the
rotation of a wheel, which is loosely keyed to the tool stock, in combination with a
vibrating friction clutch, whereby such wheel may be rotated any part of a revo-
lution within the range of motion of the vibrating friction clutch.
Sixthly. A rocking cam for operating the actuating pawl of a feed wheel, pro-
vided, first, with a short and sharply inclined face or tappet, by means of which the
cam is suddenly rocked in one direction during the latter part of the downward
stroke of the tool stock; and, secondly, with a larger or less sharply inclined face or
tappet, by means of which the cam is more gradually rocked in the opposite
direction during the return stroke of the tool stock, substantially as and for the
purpose described.
Seventhly. The cam N and the reciprocating wedge which actuates it in combi-
nation with a friction pawl and feed wheel for effecting the longitudinal feed of a
reciprocating tool stock, substantially as set forth.
Eighthly. A device for operating the feed wheel, which consists of a tappet which
gives a quick movement during the latter part of every working stroke of the tool
stock, and of the second tappet, which gives a slower motion in the opposite direc-
tion to feed the tool stock more or less during every return stroke, the amount of
such feed for each successive blow being automatically governed by the extent to
which the tool at the preceding blow has penetrated the material operated upon,
substantially as set forth.
Ninthly. A tripod for the support of a rock drill, composed of a central leg forked
at its upper end for the support of a transverse shaft, to which the cylinder is
clamped, the transverse shaft extending across and through the forked upper end of
the central leg, and terminating at its ends in balls and two side legs secured to
these balls respectively by adjustable clamps, substantially as shown.
Tenthly. In an extensible leg for a tripod, a tubular joint provided with the slit
V³ at its lower end and the clamp V2 and key V5 in combination with the extensible
joint V, provided with the longitudinal key seat V¹.
Eleventhly. An adjustable collar for sustaining the weight upon the lower joint
of the leg, provided with the laterally projecting stem W2 and set screw W³ in com-
bination with a hole Wo bored transversely through the weight W, as shown.
In witness whereof, we, the said Auguste Alexandre Goubert and Nathaniel
Waterman Pratt, have hereunto set our hands and seals, this Seventh day of
AUGUSTE ALEXANDRE GOUBERT. (L.S.)
NATHANIEL WATERMAN PRATT. (L.S.)