A tunnel-excavating machine in which a chassis carrying a cutting drum is displaceable toward the face of a subterranean structure in which a tunnel is to be formed, the chassis being provided independently from a roof-support unit which is connected to the chassis only by at least one fluid-pressure cylinder arrangement. The cylinder arrangement is connected to the unit and/or the chassis by vibration damping means so that the cylinder arrangement can advance the chassis relative to the roof support unit or vice versa and vibration transmission from the chassis to the roof support unit is damped.

FIELD OF THE INVENTION 
The present invention relates to a tunnel-excavating machine and, more 
particularly, to an excavator for subterranean courses in the production 
of tunnels and the like. 
BACKGROUND OF THE INVENTION 
In German Printed Application (Auslegeschrift) DT-AS 25 43 501, there is 
described a tracked vehicle for the excavation of subterranean courses in 
the production of tunnels and the like which comprises a forwardly 
extending machine beam having one or more excavating drums which generally 
are intended to cut the face of the subterranean structure along the 
bottom of the excavation to be produced therein. In addition, the vehicle 
carries an outrigger excavator which can cut upper portions of the face. 
The milling or cutting head on this arm, which is swingable about a 
vertical axis and can be raised and lowered with respect to a horizontal 
axis, is rotated, in turn, about an axis of rotation which generally 
extends in the direction of advance of the vehicle. 
While this apparatus has been found to be highly effective with respect to 
a highly stable subterranean structure, problems are encountered when the 
structure is not highly stable and timbering is required proximal to the 
cutting operation. While the vehicle is generally provided with means for 
timbering or affording roof support immediately downstream of the beam and 
vehicle structure, this does not always suffice. 
There is also known a tunnel-excavating machine, generally referred to as a 
DEMAG apparatus, which is provided with an outrigger arm having an 
excavating head without the aforementioned excavating drum for 
undercutting the face to be excavated. In this apparatus, however, means 
is provided for supporting the roof of the excavation and such means 
includes a cantilevered cap which reaches forwardly close to the cutting 
operation. Such apparatus can be used in less stable structures but it has 
been found that problems are encountered primarily with respect to the 
transfer of vibration to the roof-supporting unit. As a consequence, 
high-frequency oscillations can develop in the machine which can approach 
the characteristic or resonance vibration frequency thereof and endanger 
the tunnel-excavating operation as well as the machine itself. 
Particularly massive support units are required to brace the machine 
against these vibration phenomena. 
OBJECT OF THE INVENTION 
It is the principal object of the present invention to provide an improved 
tunnel-excavating machine which has the advantages of both types of 
apparatus described but is free from the disadvantages thereof. 
SUMMARY OF THE INVENTION 
This object and others which will become apparent hereinafter are attained 
in accordance with the present invention by providing a chassis which is 
displaceable in the direction of the face to be excavated and is followed 
by a roof-support or timbering structure which can be braced against the 
roof and floor of the tunnel. This support structure can be of the type 
referred to as a shielding timbering. In other words, the roof-support 
structure can have a cantilevered and forwardly extending roof-engaging 
cap which is braced against skids or the like by a plurality of posts 
which can be hydraulically operated. 
In accordance with the present invention, the displaceable chassis and the 
roof-support unit are connected only by a hydraulic cylinder arrangement, 
i.e. a fluid-pressure piston-and-cylinder assembly which can be used to 
shift the chassis forwardly relative to the roof-support structure or, 
conversely, to draw the roof support structure after the chassis. This 
cylinder arrangement is provided with vibration-damping means in 
accordance with an essential feature of the present invention. 
According to a feature of the invention, the cylinder arrangement is 
articulated to both the chassis and the roof-support unit, one or both of 
these articulations being provided with vibration-damping means. The 
vibration-damping means can be disposed at the hinge joint and can include 
metal/rubber or other vibration-damping sleeves of the hinge joint, 
metal/rubber laminate disks connected to the cylinder arrangement, its 
hinge and/or the roof-support unit or chassis, or a conventional 
dashpot-type shock absorber bridging the hinge joint. 
The system described above affords the significant advantage that there is 
no rigid connection between the displaceable frame or chassis and the 
roof-support frame or unit to transmit oscillations or vibrations between 
them. As a result, vibrations generated by the excavating head or drum are 
not transmitted to the roof-support unit. The roof-support unit can serve 
directly as the bracing against which the cylinder unit reacts to advance 
the chassis and the cutting tool. 
According to an important feature of the invention, the entire face of the 
tunnel can be excavated with the apparatus, not only the foot of this 
face, when the excavating tool comprises an excavating drum mounted upon a 
beam which can be swung upwardly and downwardly upon the chassis and, 
preferably, can be advanced in the direction of this face relative to the 
chassis. 
It has been found to be advantageous, in this connection, to provide the 
machine frame or chassis with supporting skids which can be advanced in 
the direction of the face and are thus disposed immediately behind the 
cutting drums. 
The cutting drums, in addition, can be subdivided into a plurality of drum 
sections which can be interconnected by universal joints and can be 
individually and relatively inclined to the horizontal and/or vertical. 
Thus, when the drum's sections are inclined successively from lower 
positions to upper positions, gradually the entire face of the 
subterranean structure can be excavated without putting undue strain on 
the drive motor for the drum. 
In addition, the drums can be provided with cutting teeth of helical 
configuration so that the drums not only act as excavating or milling 
cutters but also as conveyors for displacing the detritus laterally to 
longitudinal conveyors which carry the detritus out of the cutting zone. 
The support of the cantilevered roof-support elements can be effected by 
posts or the like which can be mounted upon skids of the roof-support 
structure, these skids riding on the floor of the tunnel. The cantilevered 
elements can be connected to the skids by an articulation as well. 
It should be understood that the vibration dampers can be any conventional 
means provided at the locations indicated, namely, the hinge joints or 
universal joints interconnecting the roof-support frame with the 
cutter-carrying frame. Thus any shock-damping or vibration-damping 
visco-elastic unit can be provided for this purpose. Such materials can be 
elastomers and the like. 
Advantageously, the cylinder arrangement can be inclined to the horizontal 
and can be hinged to one of these frames by a Hooke's joint bridged by the 
aforementioned dashpot-type shock absorber or the like. 
Not only does the apparatus prevent the transfer of vibration in the manner 
described, but it also allows at least the advance of the excavation 
process without manually emplaced timbering directly behind the excavating 
drum. Because the vibrations are not transmitted to the roof of the tunnel 
which has been excavated, the latter remains more stable and a cleaner 
tunneling operation is ensured with greater safety.

SPECIFIC DESCRIPTION 
The tunnel-excavating machine shown in the drawing is especially adapted 
for use in the formation of tunnels in subterranean-rock structures, one 
such tunnel being represented at 1 upstream of the machine. 
According to the invention, the machine comprises a chassis 3 which can be 
propelled by a tracked vehicle of the type described in the German printed 
application (Auslegeschrift) mentioned previously. Only the parts of the 
structure important to the present invention have been illustrated in the 
drawing and are described below. 
The self-propelled chassis 3, which can be carried at the front end of a 
vehicle provided with the necessary drive engines, carries a pair of 
machine beams 2 which can be driven forwardly in the direction of the rock 
face 6 to be excavated. 
The machine beams 2 carry, in the embodiment illustrated, a multipartite 
excavating drum 5 rotatable about a horizontal axis 4 which lies more or 
less parallel to the face 6. 
The excavating machine is also provided, rearwardly of the chassis 3, with 
a roof-support unit 7. The roof-support unit 7 has two relatively 
displaceable roof-support frames which will be described in greater detail 
hereinafter and overhang the chassis 3. 
The chassis 3 is connected with the roof-support unit 7 only by hydraulic 
advancing and retracting cylinder units 8 which are provided with 
respective vibration or oscillation dampers represented generally at 9. 
The beams 2 can either be rigid with the chassis 3 or can be mounted on the 
chassis 3 so as to telescope inwardly and outwardly. 
In a preferred embodiment of the invention, the beams 2 are swingable about 
a horizontal axis 10 upon the chassis 3. 
The chassis 3 is provided, in the region of the driven excavating drums 5, 
with forwardly displaceable support runners or skids 11. In addition, the 
roof-support unit 7 is provided with cantilevered hoods or caps 12 which 
can be displaced forwardly to a region directly above the driven 
excavating drums so as to timber or support the roof of the tunnel in the 
portions thereof last excavated by the drum. 
The support unit 7 thus comprises lower or load-supporting skids 13, 
post-like elements 14, and the aforementioned cantilevered caps or 
overhanging roof-engaging elements 12. An articulation 15 is provided 
between the skids and thr roof-engaging elements 12 so that the support 
elements 12 can be placed under stress against the roof structure 16 of 
the tunnel. 
It is self-understood, and has also been mentioned previously, that the 
machine also includes all of the necessary drive or control elements 
necessary to operate the hydraulic devices. 
Thus, the drawing shows a drive 17 for the swingable movement of the beams 
2 about their horizontal axis 10 to raise and lower the excavating drums 5 
between the dot-dash position and the solid line position illustrated in 
FIG. 1. The hydraulic cylinders 17 are articulated to the chassis 3 and 
are pivotally connected to the beams 2 at their piston rods. 
The drums 5 are provided with respective motors, not shown, and can be 
rotated. These drums may have helical excavating teeth such that, in 
addition to milling the wall of the rock structure ahead of the machine, 
they conduct the detritus inwardly, i.e. to the vertical median plane 
through the apparatus and a conveyor which carries the detritus away along 
this median plane. This conveyor is of conventional construction and need 
not be described in greater detail. 
The advancing and retracting cylinders 8, which drive the chassis 3 
forwardly relative to the roof-support units 7 which brace against the 
floor and roof of the previously excavated tunnel portions will, however, 
be described in greater detail. 
These cylinders not only serve to advance and support the chassis 3, but 
are also constructed so that they are able to hold back the chassis 3 when 
this is required for any particular application. The reaction force is 
thus applied to the roof-support unit 7. Conversely, the cylinder 
arrangements 8 can be operated to draw the roof-support braces 7 toward 
the chassis 3 when the chassis is itself braced against the lateral walls 
of the tunnel by the hydraulically actuated or mechanically displaced 
laterally spreadable elements 18 best seen in FIG. 2. 
Naturally, other means can be provided to brace the chassis 3 when the 
roof-support structure 7 is to be drawn toward the latter. 
The combination of the hydraulic cylinder arrangements 8 with vibration and 
oscillation dampers 9 has been found to be of great importance and, in 
most cases, essential to the apparatus of the present invention. 
In FIG. 3, for example, it will be apparent that the cylinders 8 are 
connected by hinge eyes to the support unit 7 at pivot joints represented 
generally at 19 and having horizontal axes. In the embodiment of FIG. 3, 
the joints 19 are provided with vibration dampers 9 in the form of 
rubber-metal laminate washers. 
In the embodiment of FIG. 4, the oscillation damping 19 is provided in a 
construction in which the cylinders 8 are disposed with a forwardly 
inclined and somewhat upward orientation. The pivotal linkage between the 
support units 7 and the cylinders 8 can be universal or Cardan or Hooke's 
joints if desired. In this case, dashpot-type oscillation dampers 21 are 
provided between the units 7 and the joint which can also be provided with 
bushings 2- or the like designed to limit the torsional stress and provide 
an oscillation-damping effect (i.e. a torsion-braking and 
oscillation-braking pivot lining). These bushings may also be of the 
metal/rubber type. 
The embodiments of either FIG. 3 or FIG. 4 ensure that the roof-support 
structure 7 will be maintained practically vibration-free and that the 
vibrations generated upon excavation of the rock structure and transmitted 
to the chassis 3 will not, in turn, be delivered to the roof support units 
7. 
This construction permits the oscillating mass represented by the chassis 
3, the beams 2 and the excavating drums 5 on the one hand and the mass 
represented by the support frame 7 on the other hand to be separated by 
elastic means such that the characteristic elastic constants of the total 
system will not permit the entire machine to be set into characteristic 
oscillation or vibration. In other words, sympathetic vibration of the 
entire apparatus is damped by the elastic and shock-absorbing connection 
between the two masses of the machine. 
Even if the operation of the excavating drums 5 imparts a characteristic 
vibration to the mass 3, 2, 5, this oscillation is partly damped at 9 and 
is not transmitted to the roof-support structure 7 to cause it to vibrate 
in its characteristic vibration mode. 
As can be ssen from FIG. 5, the excavating drum 5 can comprise four drum 
sections 5a, 5b, 5c and 5d which are connected together by 
torque-transmitting universal joints 22 and thus can be relatively 
inclined with respect to one another in horizontal and vertical directions 
as represented by the arrows 23 and 24. The relative inclination between 
the axes of these sections can be between 5.degree. and 50.degree.. 
In a preferred embodiment of the invention, the sections are displaced one 
after the other relative to the horizontal or vertical with an inclination 
so that the spikes or teeth 25 progressively bite through the rock 
structure, thereby preventing the entire cutting surface of the drum from 
having to be effective simultaneously and thereby overloading the drum 
drive. The teeth 25 are, of course, oriented to provide a screw-type 
displacement of the detritus to the center of the unit at which a conveyor 
is provided. 
Referring again to FIG. 11, it will be apparent that the roof-support unit 
7 comprises, upstanding from the skid 13 which can have a pair of skid 
runners 13a and 13b for each of the roof-support units 7, trunnions 7a and 
7b between which the eye 8a of the cylinder 8 is pivoted for swinging 
movement about the axis 8b. The trunnions 7a and 7b are carried on a 
bracket 7d of an upstanding arm 7e which is articulated at 15 to an 
upwardly and forwardly inclined arm 7f to which the caps 12a and 12b 
forming the cantilevered roof-support elements 12 are connected. The 
positions of the cylinders 14 have been shown in dot-dash lines in FIG. 1 
and it may be seen that two such cylinders are disposed on each of the 
skid members 13a and 13b to press against the cantilevered roof-support 
elements 12a and 12b which have not been shown in FIG. 2. 
The skid 11 of the chassis 3 has a pair of upstanding trunnions 3a and 3b 
which are connected by the pivot 10 to the arm 2a of the machine beam 2 
which carries the respective drums 5. The skids 11 can be formed with the 
cylinders 18 serving for lateral support. 
In operation, assuming the position of the apparatus illustrated in FIG. 1, 
in which the hydraulic cylinder posts 14 are pressurized to urge the 
roof-support elements 12 against the roof 16 of the tunnel and the skid 13 
against the floor thereof, the cylinders 18 are relieved and the cylinders 
8 are pressurized while the drums 5 are driven. Each of the drums 5, if 
they are in the configuration illustrated in FIG. 5, is progressively 
swept from the lower position shown at the left into the upper position 
shown at the right until the entire drum is in the dot-dash position shown 
in FIG. 1. The drum is then lowered, thereby displacing the detritus 
inwardly to the conveyors 40 shown in FIG. 2, these conveyors carrying 
away the detritus. During this process, the chassis 3 has been advanced to 
the left relative to the roof-support unit 7. Upon the full excursion of 
the piston rods 8c of each of the cylinders 8, the cylinders 18 are 
actuated to support the chassis 3 against the lateral walls of the tunnel. 
The posts 14 are relieved and cylinders 8 are drained or reversely 
pressurized to draw the units 7 to the left to follow the chassis 3. The 
posts 14 are repressurized to again support the roof in this region, 
whereupon the process is repeated to further advance the unit along the 
stretch of tunnel. Timbering pieces 41 can be carried by the machine so 
that they can be propped in place by posts 42 behind the apparatus for 
tunnel timbering in the usual manner. 
Aspects of the operation of the drums and conveyor will be apparent from 
the aforementioned printed German application (Auslegeschrift).