Note: Descriptions are shown in the official language in which they were submitted.
Description
RECIPROCABLY SUPPORTED DUAL~DRIVE M~MBER AND FEATURES
Technical Field
-
This invention relates to a movably supported
member which i5 reciprocable in relation to its support.
Stroke shifting means are combined with the member which are
operable to determine the location of the member's stroke
along the axis of reciprocation on the support.
Disclosure of Invention
There are various utilities for this combination.
To illustrate, in certain embodiments of the invention, a
tool is connected with the member and the member is operable
to drive the tool in relation to a work object at a work
station. Meanwhile, the stroke shifting means are operable
to enable the member to move the support thereof relative to
the object and/or the station. Also, in certain instances,
the tool is rotatably carried 0l1 the member and there are
means on the member whereby the tool can be rotated about
the axis of reciprocation thereof while the member is
reciprocating along the same.
Preferably, the stroke shifting means are operable
to shift the center of reciprocation of the member and/or
provide a forward or rearward bias to the member as it
reciprocates.
In its broadest form, one aspect of the invention
relates to a movably supported large mass member which is
reciprocable in relation to its support and has con~ointly
reciprocable drive means thereon for reciprocating the same.
Accordinq to the invention, the drive means comprise a reci-
procably ~ngaged, piston-like element, propulsion means for
reciprocating the piston-like element, and transmission
means ~hereby the member is responsive to reciprocation o~
the piston-like element to undergo its own reciprocation
3~
along a parallel to the axis of reciprocation of the piston~
like element. The effective motion of the reciprocated
large mass member is thus like the motion of a battering ram
rather than a high-frequency percussive motion. Applica-
tions for the large mass motion produced are drilling, pro-
pelling, hammering, etc. The propulsion means for recipro-
cating the piston-like element may be an internal-combustion
engine or other engine forming an integral part of the large
mass member or may be a completely external propulsion
source, such as pressurized steam, hydraulic or pneumatic
fluids, or mechanical crank mechanisms.
In many of the presently preferred embodiments of
the invention, the member defines a chamber having the
piston-like element reciprocably engaged therein to be
reciprocated between opposite ends thereof. The drive means
for the element include ~ieldable biasing means on one end
portion oE the chamber which are operable to displace the
element in one direction oE reciprocation thereof, and
servo-displacement means on the other end portion of the
chamber which are operable to intermittently displace the
element against the bias of the yieldable biasing means.
The transmission means include means on the respective end
portions of the chamber which are operable, such as by com-
pressing fluid therein, to convert the displacement oE the
piston--like element in the respective directions thereof
into reciprocable motion on the part of the member in corre-
sponding directions. For example, in certain embodiments,
the one end portion of the chamber is closed and the servo-
displacement means include means for alternately pressuriz-
in9 and depressurizing the other end portion oE the chamberto displace the piston-like element against a fluid captive
in the one end portion thereof. In some embodiments, the
servo-displacement means include means for intermittently
igniting a combustible charge in the other end portion of
the chamber and means or exhausting the combustion gases
from the same when the piston-like element is displaced as
indicated. For example, in certain emboAiments, the other
end portion of the chamber is defined by a combustion engine
.. ,~. 3. ~ ~L Ll ~ ~
having a port for exhausting the com~ustion gases from the
same when the piston~ e element is displaced as indicated,
and means whereby a new combu~tible charge can be compressed
in the other end portion of the chamber when the piston-like
element is displaced by the bias of the captive Fluid in the
one end portion thereof.
The invention also relates to a movably supported
member which is reciprocable in relation to its support and
which has conjointly reciprocable drive means thereon for
reciprocating the same, and means including a port in the
body thereof whereb~ debris can be pneumatically Elushed
away from the region ad~acent the relatively forward end of
the member in one direction of the reciprocation thereof.
In one embodiment, the drive means comprise a combustion
en~ine and the flush means include a connection between the
engine and the port whereby the combustion gases can be
conveyed to the port as the flush fluid for the debris.
In one embodiment, the movably supported tool,
which is reciprocable in relation to its support, has a
working head at one end o~ the axis of reciprocation there-
of. The head has apertures in the outer peripheral edge of
the workin~ face thereof, and there are means interconnected
with the head whereby a pressurized fluid can be discharged
through one portion oE the apertures into the region adja-
cent the face of the head when the tool is generating debrisErom the wor]s thereof. There are also means on the head
which operatively define a relatively low-pressure zone at a
point relatively rearward of the face, and means whereby
another portion of the apertures are operatively inter-
connected with the low-pressure zone so that the Eluid can
transport the debris away from the re~ion at the face oE the
head to the low-pressure zone.
In some embodiments, the apertures in the head are
disposed in the bottom portion of the head. For example, in
certain embodiments, the tool is rotatably carried in a
chuck which is reciprocably mounted in the support, and the
fluid discharge means include valve means which are operable
to prevent the fluid from communicating with the one portion
of the apertures during the upper portion of their field of
rotation when the tool is rotated in the chuc~.
In one embodiment, the apertures in the face of
the head take the form of axially extending slots in the
outer peripheral edge of the same which open into the annu-
lus at the aforesaid opposing side of the head. In some
embodiments, the slots are deeply radially inset in the body
of the head. Moreover, the face of the head is conical and
tapers relatively peripherally outwardly from the axis of
the bit in the relatively rearward direction thereof. One
portion of the apertures ta~e the form of openings which are
disposed in the face of the head intermediate the slots.
In many embodiments, the bit has percussive points
on the working face thereof, and in some, the points are
partially embedded in pads of abrasion-resistant material on
the face.
In some embodiments, a tool is carried on the
large mass member and the support for the same takes the
form of a carriage which is supported on skids on the ground
to slide over the surface thereof. The apparatus also com-
prises means whereby the carriage can be slidably advanced
along the surface of the ground when the tool is releasably
engaged with the face of the earth in the one direction of
reciprocation of the member. Also, the carriage has scoop-
like means thereon which are disposed to receive the debriswhen the carriaqe is advanced in the one direction of reci-
procation of the member and the pressurized fluid escapes
from the aforesaid region through the face of the tool.
In certain embodiments, there are restraining
means on the carriage which are frictionally engageable with
the yround to provide a counterthrust for the member along
the axis of reciprocation thereof. There are also means
whereby the carriage can be slidably advanced within an
openin~ in the face of the earth having surfaces on the
opposing sides thereof which are obliquely angled to the
horizontal of the earth, and means whereby the restraining
means can be frictionally engaged with the aforesaid sur-
faces to wedge the carriage therebetween as a component of
the counterthrust.
The invention also relates to a method for exca-
vatin~ a hole in the face of a tunnel site~ According to
the invention, a carriage is movably supported on the ground
adjacent the face of the site and a percussive tool is mov-
5 ably mounted on the carriage to be reciprocated in relationto the carriage and the ground. The tool is reciprocated in
relation to the same to impact it on the face of the site
and is rotated about the axis of reciprocation to bore a
hole in the face. In one embodiment, the tool is releasably
engaged with the carriage to move the carriage in relation
to the ground while it is impacted on the face of the site~
In this way, the tool advances the tool and carria~e unit
into the hole as it is deepened.
In certain embodiments, the carriage is friction-
ally engaged with the ground to provide a counterthrust forthe percussive action of the tool. However, the carriage is
preferably supported on skids on the ground so that it can
be trammed over the surEace of the same, or the carrier can
be a conventional tracked or wheeled vehicle.
Brief Description of the Drawings
These features will be better understood by refer-
ence to the accompanying drawings wherein the invention is
illustrated in terms of its application to a carriage-
mounted tunnel excavating apparatus.
In the clrawinqs,
FIGURE 1 is a perspective view of the apparatuswhen it is put in use in a tunneling operation;
FIGURE 2 is a side elevational view of the appara-
tus in use;
FIGU~E 3 is a front elevational view of the same;
FIGURE 4 is a top plan view of the same;
FIGURE 5 is a longitudinal cross~sectional view ofthe apparatus when the driven member of the apparatus is
approaching the rearward limit of its stroke;
FIGURE 6 iS a similar view of the apparatus when
the driven member is at the forward limit oE its stroke;
FIGURE 7 is a schematic representation of the
apparatus when it is put to use in a tunneling operation;
FIGU~E 8 iS a schematic representation of the
apparatus when it is put to use in a tunneling operation,
but being retracted from the tunnel;
FIGURE 9 is a diagrammatic representation of the
two successive operations, starting ~ith the neutral condi-
tion of the apparatus;
FIGURR 10 is a diagrammatic illustration of a
simplified form oE the invention illustrating the principle
of operation of one aspect; and
FIGURE 11 is similar to FIGURE 10 but illustrates
the principles on a conventional mobile carriage.
Best Mode for Carrying Out the Invention
-
Referring to the drawings, it will be seen that
the apparatus 13 is mounted on a carriage 19 which comprises
a tubular Erame 2 that is supported on three skid-mounted
struts 4 and 6. The more forward strut 4 is a riqid bibb-
like extension oE the frame and has a partly cylindrical
shoe 8 at the bottom thereof to form a scoop. The bottom of
the shoe is equipped with a pair of pad-like skids 9. See
Figure 2 in particular. The more rearward struts 6 are
pivotally adjustable, leg-like extensions of the frame and
have pad-like skids 12 on the bottoms thereof which are
interconnected with the frame by hydraulic cylinders 14 so
that the struts 6 can be ad~ustably angled to the frame.
Both pairs of skids 9 and 12 are slidably enga~ed with the
ground 14 so that the carria~e can be "trammed" over the
surface thereof, either in the direction of the working face
16 of the tunnel or in the opposite direction, relatively
away therefrom.
The apparatus 18 is telescopically engaged in the
axial bore 20 of the Erame 2 and comprises a combination
chuck and drive transmission sleeve 22 which is slidably
engaged in the frame so that it can reciprocate along the
axis 24 thereof but not rotate in relation to it. See the
spline 26 which is interposed between circumferelltially op-
posinq grooves 28 and 30 in the outer and inner peripheries
of the sleeve and frame, respectively. Note also that the
reciprocable motion of the sleeve is delimited by a pair of
out-turned flanges 32 and 34 on ~he opposlte ends thereo~.
These flanges operate to transmit drivin~ ~orces into the
carriage when it is desired to tram the same relative to the
face oE the tunnel, as shall be e~plained. They are actuat-
ed and deactuated in this connection by a pair of conjointly
operable control devices 36 on the carriage, as shall also
be explained. The control devices are best seen in Figures
1, 2, 4, 7 and 8.
The tunneling operation itself is performed ~y a
drill bit 38 which is carried on the sleeve 22 and assembled
with the same so that it can be rotated about the axis 24 of
the carriage while bein~ reciprocated in unison with the
sleeve. The reciprocable motion is generated by a drive
lS mechanism 40 which is disposed on the rear end portion of
the assembly 38,22. The drive mechanism is powered by a
two cycle diesel engine 42 which transmits the driving
forces through a piston 44 in the assembly, as shall be
explained.
The bit 38 is rotated by a motor-driven chain and
sprocket drive transmission 46 on the assembly. The motor
of the same can be seen at 48.
When the apparatus 18 is put to use~ the bit 38
generates excavated debris and the debris is ~lushed through
the working face 50 of the bit in a manner to be explained.
Meanwhile, the carriage is trammed toward the face 16 of the
tunnel so that the debris tends to collect in the shoe 8
thereof. Also, the collected debris is continually removed
by a conventional muck bucket-type collection device 52
which is rotatably mounted on a boss 5~ at the forward end
of the carria~e frame. The device 52 rotates about the
inner periphery of the shoe 8, scoops up the collected
debris, and raises it onto a link-supported, vibrating
trough conveyor 56 above the carriage. The debris is then
discharqed froM the trough 58 of the conveyor onto a belt
conveyor 60 ad~acent the rear end of the apparatusO
The muck collection device 52 is rotated by a
motor-driven ring gear transmission 62 mounted at the rear
3~
of the same between the boss 54 and the shoe 8D The motor
of the same can be seen at 64. The conveyor 5~ is vi~rated
by a motor-driven crank 66 which is interconnecte~ with ~he
trough 58 of the same by an articulated linkage 68. The
motor ~or the crank can be seen at 70. The belt conveyor 60
is rotated by a motor which is not shown but which is con-
nected with one roller o~ the same to drive the belt about
the idler 74.
Now referring to the drawings in greater detail,
it will be seen that the bit 3~ is conical at the working
~ace 50 of its head 76 and is slightly greater in diameter
than the perimeter of the shoe 8. The body of its head is
subdivided, however, ~y a series of symmetricallv~ angularly
spaced, deeply radially inset slots 78 at the outer periph-
eral edge 80 thereofO The slots 78 open into the back side~2 oE the head and divide the head into symmetrically, angu-
larly spaced segments 84 that merge with one another at the
flattened tip 86 thereof. Each of the segments 84 is cov-
ered by a replaceable pad 88 of studded, abrasive-resistant
material which is adapted for drilling hard rock. The tip
8~ is also covered by such a pad, but in this instance, the
pad is rounded rather than flat. ~ll of the pads are equip-
ped with a multiplicity oE percussive studs 92 which are
embedded in the abrasive-resistant material to project Erom
the face of the bit at perpendiculars thereto.
At the back side 82 oE its head, the bit is coni-
cally chamferred at the edge sn thereof and equipped with a
relatively reduced shank 94 that is sufficiently elongated
to pass through the length of the sleeve 22. The body of
the shan~c has a rearwardly oriented shoulder 96 thereon
adjacent the head, and the inside edge of the shoulder is
ormed into a cylindrical neck g8. The neck is followed, in
turn, by an annular groove 100 which is disposed about the
midsection o the body and terminates at the tail 102 of the
shank. The tail 102 is cylindrical and somewhat reduced in
diameter relative to the neck 98, and the groove 100 tapers
inwardly toward the same in the rearward direction of the
shank. The tail is also equipped with an annular groove 104
of considerably narrower width than the groove 100.
3~3
The bit 38 also has a series of ports 106 in the
head thereof which are symmetrically, angularly arrayed
about the face of the head to open through opposing aper-
tures 108 in the outer peripheral portions of the pads 88
thereon. The ports are serviced by a corresponding series
of circumferentially spaced ports 110 in the neck 98 of the
shank. The ports 110 open into a corresponding series of
passages 112 which e~tend forwardly through the neck to the
head and then extend radially outward thereof to the ports
106.
The bit also has an axial bore 114 in the rear end
116 thereoE. The hore extends forwardly through the length
of the shank and into the head of the bit, where it termi-
nates at a point short of the pad 90 on the tip oE the same.
The bottom of the bore (that is, the head end portion 118
thereoE) is radially enlarged to assume a greater diameter
than that of the main length of the bore.
~ eferring now to the sleeve 22, it will be seen
that the axial openiny 120 of the same has a stepped confiq-
uration therein so that the sleeve can be rotatably inter-
engaged with the neck 98 and the tail 102 of the bit when
the shoulder 96 of the bit is ab~ltted against the front end
face 122 of the sleeve. The tail 102 pro~ects beyond the
rear end face 124 of the sleeve, however, as indicated, and
to an extent that the groove 104 in the tail registers with
the face 124. The stepped configuration includes a bore 126
which is countersunk in the forward end of the opening 120
and extends to a depth commensurate with the relatively for-
ward end eAge 132 of the groove 100. ~s seen, the larger
3n bore 130 is siæed to rotatably engage with the neck 9~ oE
the bit, whereas the original opening 120 in the sleeve is
sized to rotatably engage with the tail 102 of the same.
Meanwhile, the smaller bore 126 defines an annular passage
134 at the interface between the sleeve and the midsection
of the shank The passage is cone-shaped in length and
terminates at the forward end edge 132 of the groove 100 in
the shank of the bit. ~owever, the passage is operatively
interconnected with the ports 110 in the neck of the bit by
3~
a partly annular circumferential groove 136 in the bottom of
the sleeve 22, which is opposed to the shoulder 138 between
the neck and the forward end edge 132 of the groove 100.
The sleeve 22 also has an inlet port 140 in the
outer periphery thereof whereby fluid can be supplied to the
ports 110 in the neck of ~he bit when the ports are rotating
through the lower half oE their field of rotation. The in-
let port is disposed on the perimeter of the relatively rear
end flange 34 of the sleeve and opens into a passage 142 in
the body of the sleeveO The passage opens, in turn, into
the bore 126 of the sleeve through a port 144 in the top
thereof. The fluid may be supplied to the inlet port by an
external supply system, such as a compressed air supply
system (not shown), or it may be supplied to the inlet port
by the diesel engine 42 of the drive mechanism 40 on the bit
and sleeve assembly, as shall be explained shortly.
Referring to the right-hand side of Figures 5 and
6 in particular, it will be seen that the bit is assembled
with the sleeve, and vice versa, by securing the sprocket
146 of the drive transmission 46 on the tail 102 oE the
same. The hub 148 of the sprocket is apertured and rabbeted
to fit over the end of the tail. It is also sized so that
the bit can rotate within the sleeve when the sleeve is
interengaged between the hub and the shoulder 96 of the bit.
Also, the rabbet in the hub 148 is countersunk at the for-
ward end thereof to receive a thrust ring 150 which is
interposed in the groove 104 of the bit across the joint
between the hub and the sleeve. Cap screws 152 are employed
to secure the sprocket to the bit, and the aperture 154 in
the hub of the same is oE such diameter as to Ereely pass
the piston 44 of the reciprocable drive mechanism 40.
The engine 42 is enclosed within a two-part
housing 156 which has a cap 158 for the sprocket 146 at the
base thereof. The cap is affixed to the rear end 124 of the
sleeve and has a partly annular, circumferential slot 160 in
the top thereof through which the chain 162 oE the drive
transmission 46 is passed to the toothed perimeter 164 of
the sprocket. It also has a central aperture 166 therein
1 1
which corresponds in diam~ter to the bore 114 of the bit.
The piston A4 is elonqated and slidably engaged in the aper-
ture 166 and the bore 114 to project within the interior of
the housing components 168 and 170. The components, in
5 turn, have a pair oE a~ially aligned chambers 172 and 174
therein for the piston. The chamber 172 o~ the relatively
rearward component 168 is adapted to slidably receive the
body of the piston, whereas the chamber 174 of the rela-
tively forward component 170 is adapted to slidably receive
10 an annular flange 176 on the rear portion of the same. The
flange and the Eront portion of the relatively forward cham-
ber 174 serve as a pump for the fresh air supply to the
engine, while the head end portion 178 of the relatively
rearward chamber 172 serves as the combustion chamber there-
15 of. The surroundinq wall 1~0 and head 182 of the combustionchamber 17~ are liquid cooled, and a nozzle 184 is installed
in the head 182 of the same for the in iection of fuel into
the chamber~ The fuel is intermixed with the fresh air, and
the mixture is i~nited in a conventional manner. The start-
20 up ignition means are not shown, for the sake of simplicity.
A plurality of seal rings 18Ç are recessed aboutthe rear end portion of the piston.
The relatively forward chamber 174 has an inlet
port 188 in the wall thereof through which the fresh air is
25 ta]cen in by the pump. The inlet port has a check valve 190
across the same to allow the air to enter the chamber when
the pump creates a pressure differential across the valve
in the direction inwardly of the chamber, hut to prevent
air~low in the opposite direction when the pump creates a
30 reverse differential thereacross. The incoming air is
cleansed by an air filter 192 at the inlet 194 of the valve
and is displaced from the chamber 174 through an outlet port
196 in the wall thereof, diametrically opposed to the inlet
port 188. The outlet port is interconnected with a third
35 port 198 in the forward end of the combustion chamber 178 by
a duct 200 on the outside of the housing 156. The third
port is diametrically opposed, in turn, by an exhaust port
202 on the opposite side of the combustion chamber at the
3~
forward end thereof. The exhaust port is connected, in
turn, to the inlet port 140 o-f the sleeve 22 by a flexible
hose 204 or the like, and the connection is valved so that
the combustion gases can be selectivel~ discharged to atmos
5 phere, or to the port 140, depending on the stage in which
the apparatus is being operated, as shall be explained.
Referring now to Figures 1 1 2, 4, 7 and 8 in
particular, it will be seen that the carriage Erame 2 has a
pair of angularly spaced ears 206 upstanding thereon at the
10 top thereof and that there is a pair of similarly upstanding
ear-like extensions 208 on the rear end flange 34 of the
sleeve. The respective extensions are axialy ali~ned with
the ears of the carriage and are equipped with a pai r of
h~,rdraulic cylinder-type servomotors 210 on the rear end
15 faces khereof. Each servomotor has a piston-like control
member 212 slidably engaged in the chamber 214 thereof, and
each control member comprises a rod 216 having a pair of
piston-like heads 213 and 220 on the opposite ends thereof.
The rod is slidably guided in the respective extension 208
20 and the ear 260 thereoPposite, and one head 48 oE the same
is slidably engaged in the chamber 214 of the respective
servomotor, as indicated. The other head 220 is spaced
outboard from the correspondinq ear, and a pair of coiled
springs 222 and 224 are caged about the rod between the ear
25 206 and the extension 208, on one hand, and between the ear
and the outboard head 220 on the other. The sprinys operate
to compensa~e for momentum lost by the bit and sleeve assem-
bly 38, 2 when it is used in tramminq the carriage and/or
excavating the tunnel, as shall be e~plained; whereas the
3n servomotors enable the effect oE the springs to be altered
for purposes o actuating and deactuatinq the tramming
eEfect, as shall also be explained.
Reerring now to Figures l, 2, 4, 5 and 6 in
particular, it will be seen that the boss 54 on the forward
35 end o the carriage frame 2 has an annular housing 226
thereabout which opens to the front of the apparatus~ Also,
there is a partly annular muck ring 228 connected upright
about the front of the bibb-like strut 4 at a diameter
3''3
13
intermediate that of the housing 226 and that of the shoe 8.
A ball bearing ring 230 is seated on the boss at the mouth
of the housinq and is held in place by an annular bushing
232 which is secured to the forward end of the boss. The
bushing registers with the inner race 234 of the bearing,
and together with the same, forms a journal 235 for an
annular disc 236 which is rotatably mounted on ~he outer
race 238 of the bearing. The disc has a hub 2~0 and four
lipped~ side-loading muck buckets 242 symmetrically, angu-
larly arranged about the outer periphery thereof. The buck-
ets are rotatably interengaged between the inner periphery
of the shoe 8 and the muck ring to collect the debris on the
bottom of the strut 4. The debris is then transported in
conventional fashion to the terminal edge 2~4 of the muck
ring at the top thereof. See Figure 1. The hub 240 has ~he
gear 246 of the transmission 62 secured to the rear Eace
thereo~, and the gear is driven by a spur gear 248 on the
motor 64 of the transmission. The motor is mounted within
an aperture 250 in the strut 4.
When the apparatus 18 is put to use, initially the
piston 44 is put into motion by operating the servomotors
210 as double-acting cylinders or by pumpin~ charges of com-
pressed air into the head end portion 1 18 of ~he bore 114 in
the bit. Either approach has the effect of generating rela-
tive motion between the piston and the bit and sleeve assem-
bly so as to enable the engine 42 to be started. Once the
engine is running, successive fuel-air mixtures can be com-
pressed and ignited in the combustion chamber 178 of the
same to operate the engine in conventional fashion. More-
over, each cycle of the engine displaces the piston forward-
l~ from the chamber, and the resul~ing forward motion oE the
piston operates to compress the air trapped in the head end
portion 118 of the bore 114, as well as to compress the air
ahead o~ the piston flange 176 in the pump chamber 174. The
latter effect operates to force a new fresh air charge into
the combustion chamber through the duct~connected ports 196
and 198. The new charge floods the chamber, and in doing
so, displaces the residual combustion gases through the
3~
14
exhaust port 202. Meanwhile, the trapped air in the head
end port:ion 118 of the bore 114 operates as a yieldable
biasing mediu~; and when the accumulated pressure of the
same overcomes the motion of the piston, the piston is
reversed and driven in the opposite or rearward direction of
the bore~ As the piston returns to the combustion chamber,
the flange 176 on the same opens the ports 188 and 196 and
generates a suction condition in the pump chamber 174. This
opens the valve 190, and a new charge of air is taken in
through the inlet 194 of the same. The piston is then re-
displaced in the Eorward direction of the bore by the igni-
tion of a new fuel-air charge in the combustion chamber, and
the operation is repeated again and again to cause the
piston to reciprocate within the bit and sleeve assembly.
As the piston reciprocatesr it generates the same
motion in the assembly 3~,22 itselE, inasmuch as the piston
alternately compresses the air masses at the ~orward and
rearward ends 118 and 178, respectively, of the assembly.
The d~namics oE the resultin~ motion on the part of the
assembly are controlled in part by a throttle on the engine,
which, for the sa~e of simplicity, is not shownO However,
the useful application of these dynamics is determined
more by the efEect of the control devices 36, which, as
explained, are interposed between the carriage and the
reciprocating assembly.
Referring now to Figures 1, 2 and 4-9 in particu-
lar, it will be seen that when the engine is under way, the
stroke oE the bit and sleeve assembly works against the bia~
of the respective pairs of springs 222 and 224 in the de-
vices 36. This bein~ the case, the energy stored in eachsprin~ pair operates to effectively restore any momentum
lost by the assembly as it reciprocates counter thereto. In
addition, the relative biases of the respective spring pairs
operate to locate the stroke of the assembly along the axis
24 of the carriage. That is, the net differential between
the biases determines where the stroke can take place on the
axis; and this being the case, it is also true that the net
differential can be used -to relocate the stroke, that isl to
shift it to a new location on the axis without diminishing
or enlarginq the length of the same.
The servomotors 2~0 are operated to vary the
differential for this purpose, particularly in the sense of
either locating the stroke of the assembly so that the
flanges 32 and 34 of the same clear the stops constituted by
the forward and rear end ~aces 252 and 254 of the carriage
~rame 2, or shifting the stroke so that one or the other of
the Elanges engages the corresponding stop on the carriage
frame. The servomotors may be operated to reciprocate the
assembly in relation to the carriage and the ground 14 with-
out engaging the work face 16 of the tunnel. In such a
case, the assembly can be said to be undergoing lost motion
with respect to both the carriage and its support, i.eO, the
ground. ~lternatively, they may be operated to reciprocate
the assembly in engagement with the face of the tunnel while
it is undergoing lost motion with ~espect to the carriage.
In such a case, they are being used simply to enable the
assembly to drive the tool constituted by the bit 38 without
advancing (or retracting) the carriage at the same time. To
advance the support in one embodiment, it is necessary to
operate the servomotors in the sense of reciprocating the
assembly in engagement with both the carriage and the face
of the tunnel, either simultaneously or alternatively, or
both. Of course, the control devices 36 provide this capa-
bility since they can vary the stroke of the assembly to
drive the carriage alone or they can vary the stroke of the,
assembly to drive both the carriage and the bit.
In the case where the large mass member carries a
tool and is on a conventional mobile carrier, the servo-
motors will advance the tool into the work surface as the
work surface face gets impacted away, thus allowing the
carrier to be advanced only intermittently.
Referring now to Fiqures 7-9, and to Figure 9 in
particular, it will be seen that these possibilities are
schematically and diagrammatically illustrated in terms of a
typical rock drilling operation. Initially, at the left-
hand side of the diagram in Figure 9, the springs 222 and
16
224 of the control devices 36 are balanced and the apparatus
is standinq off from the rock face 256 of the tunnel at such
distance that the bit and sleeve assembly can achieve no im-
pact on either the face 256 or the carriage 2. This is the
neutral condition of the assembly in that it is undergoing
lost motion with respect to the ground, the face and the
carriage. However, moving to the right on the diagram, it
will be seen that the servomotors 210 can be operated to
cause the outboard heads 220 of the control members 212 to
compress the front springs 224 of the devices to ~he point
where the rear end flanqe 34 of the assembly will impact the
carria~e at the rear end stop 254 thereoE and cause the car-
riage to tram forward toward the rock face. Subsequently,
as the bit 38 approaches the face, the engine ~2 can be
throttled to give it more power and the compression on the
springs 22~ can be increased to compensate for the impact oE
the bit on the face~ Meanwhile, the assembly can continue
to impact the carriage for purposes of advancing it into the
face as the drilling operation proceeds therein. The ad-
2n vance of the bit is schematically indicated at 258~ whereas
the corresponding carriage advance is indicated at 260.
Should it become necessary or desirable to reverse the
direction of the carriage, such as to retract it from the
tunnel, the servomotors 210 can be operated to release the
25 front springs 224 to the point where the springs 222 and 224
are unbalanced in the opposite direction and the front end
flan~e 32 of the assembly is caused to impact the carriage
and ~roduce reverse tramming of the same away from the rock
face.
When the apparatus 18 is at the rock face, the
motor 4~ is normally operated to rotate the bit. Also, the
motors 64 and 70 are actuated, and the connection 204 be-
tween the exhaust port 202 of the engine and the inlet port
140 of the sleeve is opened to discharge the combustion
qases through the ports 106 in the head of the bit as the
ports rotate through the bottom hal~ of their field of rota-
tion. The ti~ing is such that the "pulses" of combustion
gas discharge through the ports when the face of the bit is
~ 7
reciprocating in the direction relatively away from the face
of the tunnel. As a consequence, the discharged gases enter
the region between the faces when there is a gap 262 opened
to them, and once in the gap, they effectively fluidize and
entrain the excavated debris at the toe of the gap and then
escape back through the slots 78 in the bottom half of the
bit to remove the debris from the gap. Moreover, when the
face of the bit is reciprocated in the opposite direction on
the next stroke of the bit, i.e., toward the Eace of the
tunnel, the gases in the gap are "pumped" and recompressed
by the face of the bit in the manner of a bellows to main-
tain the flow of debris through the slots of the bit. Mean-
while, the displaced debris enters the relatively low-pres-
sure annulus 264 behind the head of the bit and deposits on
the inner periphery of the shoe 8, where it is promptly
removed by the buckets 242 of the muck collection device
rotating therewithin. The continual forward movement of the
shoe also lends itself to this effect~ in much the same
manner as one must continually "scoop" a dustpan forward
when it is used in cooperation with a whisk broom if one is
to achieve the maximum effect on the part of the broom.
Each bucket of the muck collection device lifts a
portion of the debris upward about the muck ring 228 until
the debris encounters the terminal edge 2~4 of the same at
the top thereof. At this point, the debris tumbles onto the
trough 58 of the vibrating conveyor 56 and is thereafter os-
cillated rearwardly of the same until it ultimately tumbles
onto the bel-t conveyor 60 for removal from the tunnel site.
Ordinarily, the pulses of combustion qases are
timed so that the back pressure at the face of the tunnel is
at a minimum and the size of the gap 262 is such that the
larqer particles in the debris are able to escape through
the slots without being qround against the face of the
tunnel beforehand.
In many operations, a steady flow of pressurized
fluid is more desirable, and in such a case, a compressed
air supply is commonly used in lieu of the illustrated
engine hookup. Also, an airflow is commonly employed where
3~
18
the combustion gases will pose an excessive pollution prob-
lem, such as where the gases cannot be readily exhausted
from the tunnel site during the tunneling operation.
In addition to serving as skids on which the
carriage can be trammed over the surEace of the ground, the
pads 9 on the bottom of the shoe 8 also function as re-
straining means with which to provide a counterthrust for
the bit along the axis of reciprocation thereof~ Moreover,
referring again to Figure 2~ it will be seen that the pads 9
are not only symmetrically disposed on the outer peripheral
surface of the shoe, but they are spaced apart from one
another at acute angles to the vertical plane of the axis of
reciprocation of the bit. As a consequence, the pads are
Erictionally engageable with the rounded but ~enerally
obliquely angled sidewall surfaces on the opposing sides of
the trench-like bottom portion of the tunnel, and in this
disposition, generate substantial, oppositely directed,
horizontal components in their bearing forces, which, in
turn, generate a wedge effect between the surfaces as a
major component of the counterthrust. In theory, the maxi-
mum wedge effect can be achieved by placing the pads near
the horizontal plane of the axis. However, in practice, the
pads are arranged somewhat below this plane, yet at suffi
cient height to generate enough wedge effect to counter the
maximum thrust anticipated for the particular sleeve and bit
assembly to be carried by each carriage; and the disposition
and number of skids are varied from one carriage to the ne~t
as is necessary to vary the hori~ontal and vertical compo-
nents oE the bearing forces for this purpose.
While the embodimen~ illustrated shows a Eull
~unnel face impacting application for the invention, it
should be understood that a conventional mobile carrier 300
(Figure 11 ) can also be employed~ In this application, the
large mass member 310 may be made smaller to be supported on
a positionable support 320 which can be positioned by an arm
and angled by an actuator 340.
The device can also be used for vertical pile
driving or a Yariety of other applications requiring large
mass lmpactlng.
