US3640573A

US3640573A - Tunneling machine

Info

Publication number: US3640573A
Application number: US863783A
Authority: US
Inventors: Frank Safar
Original assignee: Smith International Inc
Current assignee: Smith International Inc
Priority date: 1969-10-06
Filing date: 1969-10-06
Publication date: 1972-02-08
Anticipated expiration: 1989-02-08
Also published as: DE2023418A1; JPS4839980B1; ZA702667B; DE2023418B2; GB1295153A; GB1295152A

Abstract

A tunneling machine having a main support frame and also a movable frame which is longitudinally movable in stepwise fashion as the tunnel is being drilled, in which a main bearing assembly is utilized for transmitting both forward thrust and rotating drive to a cutting wheel, the main bearing assembly having a stator (housing) to which forward thrust is imparted by separate forward thrust drive means, the stator being attached to the forward end of the movable frame for pulling it forward, the main bearing assembly also including a rotor which directly drives the cutting wheel and which receives rotational drive through a mated pair of driving gears from the drive shaft of the machine; the rotor being supported from the stator by both radial and thrust bearings, and the pair of driving gears being longitudinally slidable so that vibration stresses from the cutting head are not transmitted back through the drive shaft to the rotating drive mechanism of the machine.

Description

United States Patent [151 3,640,573 Safar Feb. 8, 1972 [54] TUNNELING MACHINE Primary Examiner-Ernest R. Purser [72] Inventor: Frank Safar, Fullerton, Calif. Atmmey Beehlen Amt & Jagger [73] Assignee: Smith lntemational, lnc., Newport Beach,

Calif. [57] ABSTRACT [22] Filed; Ga 6, 1969 A tunneling machine having a main support frame and also a movable frame which is longitudinally movable in stepwise [21] Appl' 863783 fashion as the tunnel is being drilled, in which a main bearing assembly is utilized for transmitting both forward thrust and 52] us. CL ..299/31, 299/60, 299/90, mating drive to a cutting wheel the main bearing assembly 1 308/174 having a stator (housing) to which forward thrust is imparted [51 Int. Cl ..E01g 3/04 by Fame fmwmd drive means the being [58] Field of Search "299/31 60 308/174. 64/9 tached to the forward end of the movable frame for pulling it 64723 forward, the main bearing assembly also including a rotor which directly drives the cutting wheel and which receives 56 R f rotational drive through a mated pair of driving gears from the l 1 e erences drive shaft of the machine; the rotor being supported from the UNITED STATES PATENTS stator by both radial and thrust bearings, and the pair of driving gears being longitudinally slidable so that vibration stresses 1,647,853 11/1927 Budd et al ..308/ 174 X from the cutting head are not transmitted back h h h 3,357,208 12/1967 Chase drive shaft to the rotating drive mechanism of the machine. 3,383,138 5/1968 Scaravilli et a1 3,51 1,539 5/1970 Schonfeld ..299/3l X 17 Claims, 12 Drawing figures I I l W 22 60 a TELESCO /NG 500 weusr 456's 65 an {N052 GEde 50X Z/0 Haas/N6 80 M4l/V SOP/ 027' 2/5 FEAME\ MOTOQ fl/ysr mameae 6540016 FQAME eAQ/AL //0 sis-Mew; fl 33 2 ,45; 54 /0//vc- 6542s /'"i:Q:1

-- A 5555/66 wee 250 E s .s a

2614.2 Side/N6 7'6Z$'C0 //V A03 466-5 H F007 PATENTED FEB 8 I972 SHEET 2 0F 9 PATENTEDFEB 8 I972 SHEET 3 OF 9 INVENTORY [FAA/Z 54/ /42 PATENTEU FEB 8 I972 SHEET 6 [IF 9 e mm M w PAIENIEDFEB am 3.40.57

SHEET 7 UF 9 INVENTOR. en/we 54/642 BY 61% /M PAIENIEBFEB 81972 sum 8 0r 9 QQN PATENTEUFEB 8 I972 sum 9 0r 9 INVENTOR. 1 24466 541C142 TUNNELING MACHINE BACKGROUND OF THE INVENTION The present invention relates to tunneling machines having a rotary boring head or cutting wheel for cutting passages through hard rock and minerals. Machines of this type frequently carry stress loads of a million pounds or more. The high degree of hardness of material being cut reflects a heavy stress load on the boring head or cutting wheel, and this stress load in turn must be carried by a bearing mechanism which permits the boring head or cutting wheel to rotate, and must also be transmitted to other supporting portions of the machine.

It is well known in the art in a machine of this type to utilize a main support frame and a movable frame, which are longitudinally movable relative to each other, thus permitting a stepwise advance of the machine in a forwardly direction as the tunnel is being cut. The main frame typically has a set of forward shoes and a set of rearward shoes, each of which may be extended for supportive engagement with the tunnel wall. The movable frame also has a forward shoe and a rearward shoe which support both frames during the time when the main support frame is being relocated in the tunnel. A machine of this general type is shown, for example, in US. Pat. No. 3,383,138.

Heretofore, the machines of this general type have suffered from a very short useful life before rebuilding or major repair has been required. The primary object and purpose of the present invention is to provide an improved machine of the type described, which has a long useful life before rebuilding or repairs are required.

An additional object of the invention is to provide a machine of the foregoing type, which is so arranged that a main bearing assembly supporting the boring head or cutting wheel may be easily removed and replaced without a substantial loss of the working time of the machine.

A further object of the invention is to provide a tunneling machine of the wheel type in which heavy cutting loads on the cutting wheel are not reflected into the rotating drive mechanism.

DRAWING SUMMARY FIG. I is a schematic diagram showing the main operative parts of the machine;

FIG. 2 is a side elevational view of a tunneling machine in accordance with the present invention, located in a cutting position within a tunnel;

FIG. 3 is a vertical cross-sectional view of the machine taken on the line 33 of FIG. 2;

FIG. 4 is a vertical cross-sectional view of the machine taken on the line 4-4 of FIG. 2;

FIG. 5 is a vertical cross-sectional view of the machine taken on the line 55 of FIG. 2;

, FIG. 6 is a transverse cross-sectional view of the machine taken on the line 6-6 of FIG. 3, but showing the rear end portion of the machine;

FIG. 7 is a longitudinal cross-sectional view of the front end portion of the machine taken on the line 7-7 of FIG. 3;

FIG. 8 is an enlarged view like FIG. 7;

FIG. 9 is a transverse cross-sectional view taken on the line 9-9 of FIG. 8;

FIG. 10 is an interior detail view taken in the circle 10-10 of FIG. 8;

FIG. 1 l is an interior detail view taken in the circle llll of FIG. 8;

FIG. 12 is a perspective view of the easily removable main bearing of the machine.

PREFERRED EMBODIMENT GENERAL DESCRIPTION-FIG. l The tunneling machine of the present invention will first be generally described with reference to FIG. I of the drawings.

LII

The tunneling machine includes a main support frame 50 having front telescoping legs 60 and rear telescoping legs 65 which are adapted for outward extension to grip the tunnel wall. Thrust cylinders carried at the forward end of main support frame 50 provide a forward thrust drive means and are expanded for driving the operative portions of the machine in a forwardly direction so as to force the cutting wheel 300 against the end face of the tunnel.

A movable frame is disposed within the main support frame 50, and is longitudinally movable relative to the main support frame. All of the operative portions of the tunneling machine are connected or coupled, either directly or indirectly, to the movable frame 110. Thus themachine as a whole can be advanced stepwise in the forwardly direction. The procedure is that themain support frame 50 is located in a particular longitudinal position within the tunnel; the

telescoping legs

60 and 65 are extended into engagement with the tunnel walls so as to rigidly support the main support frame in that location; and the thrust cylinders 80 are then expanded forwardly until a particular cutting stroke has been completed.

Auxiliary shoes

160 and 165, associated with the forward and rearward ends, respectively, of the movable frame 110 are then used for supporting the entire machine while the main support frame 50 is being relocated to a more forwardly advanced position. This general mode of advancing the machine is well known in the art and hence need not be described in further detail.

Although the specific mechanism is not shown in FIG. I, the movable frame 110 is supported in a nonrotative relationship to the main support frame 50, but is free to move longitudinally relative to the main support frame 50, and is preferably supported in a longitudinal sliding relationship relative to the main frame 50.

A main drive shaft is disposed inside the movable frame 110, and is advanced along the tunnel in conjunction with the movement of the movable frame. A rear bearing I25 supports the rearward end of drive shaft 130 for rotation relative to movable frame 110. A gear box is attached to the rear- -ward end of movable frame 110, and is also coupled to the rearward end of the main drive shaft 130. A drive motor associated with gear box 135 is operable for imparting a rotating drive to the drive shaft 130, so that the drive shaft will rotate relative to the movable frame 110. The rear auxiliary shoe I65, although it could be attached directly to the rearward end of movable frame 110, is for convenience attached underneath the gear box 135.

To complete the rotating drive mechanism a pair of driving gears 150, are located at the forward end of the main drive shaft 130. The drive gear ISO is a male gear which is rigidly attached to the forward end of drive shaft 130. The driving gear 155 is a female gear which is rigidly (but removably) attached to the rotor 220 of main bearing assembly 200. An important feature of the present invention is that the female gear 155 is free to slide longitudinally, at least to some extent, relative to the male drive gear 150. The significance of that feature of the machine will be described subsequently.

A main bearing assembly 200 is used to support and to drive the main cutting wheel 300, and concurrently receives both the forward thrust drive from thrust cylinders 80 and the rotating drive from drive shaft 130. The main bearing assembly 200 includes a housing or stator 210 which is of a generally hollow cylindrical configuration. A rotor 220 is disposed concentrically within the housing 210, and is supported for rotation relative to the housing by means of a front end radial bearing 240 and a rear end radial bearing 250. Removable attachment means such as bolts 221 are employed for removably attaching the female drive gear I55 to the rearward end of rotor 220. Removable attachment means such as bolts 222 are used for removably attaching the main cutting wheel 300 to the forward end of rotor 220.

The rearward end of housing or stator 210 is removably at-. tached to the forward end of movable frame 110, as by means of bolts 211. The forward thrust of the thrust cylinders 80 is applied to a thrust collar 215 fonned on the housing 210, hence the forward thrust of the thrust cylinders 80 serves to pull the movable frame 1 in a forwardly direction.

Also located between the housing 210 and the rotor 220 is a thrust bearing 230, which is disposed intermediate to the forward and rearward end bearings. The function of the thrust bearing 230 is to impart a forward thrust drive from the housing' or stator 210 into the rotor 220. The associated mechanism includes an interior thrust collar 217 on the housing 210 which has a forwardly facing thrust shoulder, and an exterior thrust collar 225 on the rotor 220 which has a rearwardly facing thrust shoulder, the thrust bearing 230 being supported between these two thrust shoulders.

The forward auxiliary shoe 160, although it could be attached directly to the forward end of movable frame 110, is for convenience attached under the housing 210.

During a cutting operationof the machine the cutting wheel 300 receives both rotational and thrust loadings which vary over a wide range in a rather unpredictable manner, with the peak loadings being very high. In most or all of the prior art machines for tunneling in hard rock or hard minerals, the longitudinal thrust force of the machine as well as vibrational stresses are imparted through the main drive shaft into the rotating drive mechanism. According to the present invention, however, the female drive gear 155 is longitudinally slidable relative to the male drive gear 150, hence the longitudinal and vibrational stresses imparted from cutting wheel 300 to rotor 220 are not transmitted to the drive shaft 130, except perhaps with a greatly reduced magnitude. The gear box 135 is thus protected from any extraneous interference, and is free to perform its simple function of imparting a rotating drive to the drive shaft 130, under conditions which permit it to have a long useful life and to operate relatively free of maintenance requirements.

Another significant feature of the invention is that the main bearing assembly 200 is arranged for easy removal, in its-entirety, from the tunneling machine. Thus the coupling of thrust cylinders 80 to the thrust collar 215 of housing 210 is such as to permit easy detachment of the housing 210 from the'thrust cylinders. Removable bolts 211 also permit easy detachment of housing 210 from the movable frame 1 10. Removable bolts 221 permit easy detachment of female drive gear 155 from rotor 220, and removable bolts 222 permit easy detachment of cutting wheel 300 from the rotor. The

radial bearings

240 and 250, and the thrust bearing 230, involve a large number of individual parts, and these bearing mechanisms tend to wear during operation of the machine. The easily removable nature of the attachments of housing or stator 210 and of rotor 220 to the other parts of the machine makes it possible to remove the entire main bearing assembly 200 as a unit. A new main bearing assembly may be inserted in the tunneling machine with comparatively small loss of working time. The worn or damaged main bearing assembly may then be transported away from the construction job to a shop or factory where its repair or overhaul may be conducted on a more leisurely ba- SIS.

In utilizing the tunneling machine of the present invention it may be preferred, however, to replace the main bearing assembly 200 periodically as a preventive maintenance feature. In that case, the main bearing assembly which is removed may not be significantly worn or damaged at all, but replacing the old assembly with a new one involves only a short down time for the machine and insures a long uninterrupted operating time for the machine when its useage is resumed.

DETAILED DESCRIPTIONFIGS. 2 to 12 The presently preferred embodiment of the invention, as illustrated in drawing FIGS. 2 to 12, inclusive, will now be described in some detail.

The structure and operation of the machine has already been described with reference to FIG. 1, where the various component parts of the machine are illustrated schematically, rather than in accordance with their precise mechanical construction. The reference numbers used in FIG. 1 are also applied to the corresponding parts of the machine in FIGS. 2 through 12, hence it will be understood that in FIG. 1 the particular reference number applies to a schematic representation of the part, whereas in FIGS. 2 through 12 the same reference number indicates the actually preferred, precise form of the same part.

The schematic representation of the machine in FIG. 1 ignores the fact that in addition to the circular main cutting wheel 300 the machine also includes a center drill 400. The detailed drawings illustrate a drive mechanism and a bearing support assembly for the center drill, which are concentrically arranged relative to the main drive shaft and main bearing assembly. Before going into a detailed description of the'center drill and its associated bearing assembly and drive mechanism, however, it will be advantageous to describe in detail the main portions of the machine which have already been discussed in connection with FIG. 1.

Thus the main support frame 50 has a square cross-sectional configuration and is formed of two separate frame halves 52, 54 which are joined together by bolts 58 (FIG. 4). Each of the telescoping front legs 60 has a leg base 62 onto which ribs 56 are attached for purposes of structural reinforcement. Similar rib structures are also associated with the leg bases 67 of the rear telescoping legs 65. Wear bars 70 are attached to the interior corners of the housing structure 52-54 and provide surfaces within which the guide tube 115 may slide longitudinally. The wear bars 70 are preferably made of machined brass material.

The actual physical structure of movable frame 110 includes a guide tube 115 whose cross-sectional configuration is in the form of a hollow square (FIG. 4) and which extends throughout the greater part of the length of the machine. The exterior corner surfaces of guide tube 115 slide within the wear bars 70, the wear bars being located at both the forward and the rearward ends of housing 50. A circular ring 117 is welded onto the forward end of guide tube 115 (FIG. 7 and 8) and forms the forward end portion of movable frame 110. A v

circular ring 119 is welded to the rearward end of guide tube 115 and forms the rearward end portion of movable frame 1 10.

A front bellows and a rear bellows 77 constitute, in a sense, extensions of the main support frame 50 (FIG. 2). The purpose of these bellows is to prevent dirt and other foreign materials from entering into the interior spaces between housing 50 and guide tube 1 15, in which a precisely controlled Ion gitudinal sliding action of the movable frame 110 needs to be achieved. The front bellows 75 therefore has its rearward end attached to the front end of housing 50 and its forward end attached to the guide tube forward ring 117 (FIG. 8). The rear bellows 77 has its forward end attached to the rearward end of housing 50 while its rearward end is attached to the ring 119 (FIG. 6).

There are four of the thrust cylinders 80 located at the top, bottom, and sides of main support frame 50 (FIG. 3). Each thrust cylinder has an associated cylinder rod 83 which is extendable in the forward direction for imparting the thrust force. A removable thrust collar 85 slides over the rearward portion of housing 210 of the main bearing assembly (FIGS. 2, 7) and has circumferentially spaced ears 86 in which pins 87 are carried, each pin 87 being pivotally connected to the forward end of the associated rod 83. Removable bolts 88 are used to attach the forward end of thrust collar 85 to the thrust collar 215 of housing 210. The specific configuration of thrust collar 215 is shown in FIGS. 7, 8, and 12.

The main drive motor 140 which is schematically illustrated in FIG. 1 by a single block is in fact a group of six separate motors disposed about the periphery of gear box 135 (FIGS. 2,5). Each of these motors drives a bull gear 137 (not shown) which 'is attached to the rearward end of drive shaft 130. During cutting operations of the machine the forward end of drive shaft is supported by the

gears

150, 155. When the main bearing assembly 200 is removed from the machine, however,

it becomes necessary to independently support the front end of the drive shaft, and for this purpose a support ring 127 is provided within the forward end of guide tube 115.

In the main bearing assembly the front radial bearing 240 has an inner ring or raceway 242, an outer ring or raceway 246, and cylindrical bearings 244 which are retained between the two raceways. A front bearing retainer 260 is attached both to the housing 210 and to the rotor 220 for shielding the bearing 240 from dirt.

Rear radial bearing 250 includes an inner ring or raceway 252, an outer ring or raceway 256, and cylindrical bearings 254 which are disposed between and retained by the two raceways. There are two separate retainers for the rear bearing, the outer one being designated as 270 and the inner one as 280 (FIG. 8). A rotary seal 275 is located between retainers 270,280.

Thrust bearing 230 includes a rear thrust plate or ring 231 which is supported from the thrust collar 217 of housing 210. A bearing cage 233 (FIGS. 8, 9 and 10) has radial legs, and on each radial leg there are three cylindrical bearing members 234 disposed for rotation. The thrust ring or plate 231 lies in a plane that is transverse to the longitudinal axis of rotor 220, and the outer circumferential surface of ring 231 firmly engages the interior wall surface of housing 210 while its inner circumferential surface is spaced away from the rotor 220. The cylindrical bearing members 234 ride on the forward flat surface of the rear pressure plate 231, and also ride on the rear flat surface of the rear pressure plate 231, and also ride on the rear flat surface of a forward pressure plate 235. Pressure plate 235 is disposed parallel to the pressure plate 231, having its interior circumferential surface in firm engagement with the exterior surface of rotor 220 to rotate therewith while its outer circumferential surface is spaced away from housing 210. The forward flat surface of pressure ring 235 bears against a spacer ring 225.

It will be noted that in FIG. 1 the reference numeral 225 applies to a part which is schematically illustrated as a thrust collar formed on the exterior surface of rotor 220. In the preferred embodiment of the invention, however, the member 225 is in fact a spacer ring which is slid over the exterior surface of rotor 220, the forward edge of the spacer ring being lodged against inner raceway 242 of the front radial bearing 240. The raceway 242 is, in turn, lodged against a shoulder 226 of rotor 220. Hence, the spacer ring 225 is supported against forward motion relative to the rotor 220, and forward thrust bearing 230 is operative to impart forward thrust from housing 210 into the rotor 220 in the manner which is schematically illustrated in FIG. 1.

The tunneling machine of the present invention is designed for a forward loading on the cutting wheel of approximately 1 million pounds, and this forward loading is also carried by the thrust bearing 230, thus involving the possibility of a substantial deformation of the component parts of the thrust bearing and associated mechanism. Before placing the machine in operation the parts are aligned in such a way that a rear thrust plate 231 of thrust bearing 230 is spaced a predetermined amount, such as 0.030 inches, from the thrust collar 217 of housing 210. A plurality of recesses 218 are formed in the thrust collar 217, and a separate compression spring 232 is placed within each of the recesses 218 so as to provide a forward pressure against the thrust plate 231, Associated peepholes 212 are formed in the housing 210 so that the initial spacing between thrust plate 231 and thrust collar 217 can be observed, measured, and hence established at its proper value.

The main cutting wheel 300 includes a central hub portion 310 which is machined so as to fit precisely over the forward end of rotor 220. The outer or main part of the cutting wheel and the hub portion are welded together to form an integral structure. A number of the bolts 222 pass through corresponding openings in hub portion 310 and into appropriately located threaded openings of the rotor 220. (FIG. 7). Cutters 320 are mounted about the circumference and face of the cutting wheel 300, as shown in FIG. 2. In the preferred embodiment of the invention there may typically be 31 of these cutters.

The thrust cylinders which are used to drive the machine forward during its cutting stroke may also be used for retracting the cutting wheel 300 away from the tunnel face. The bolts 88 (FIG. 7) provide a positive coupling to the main bearing housing 210 so that it may be withdrawn in the rearward direction. Thrust bearing 230 is effective for thrusting the rotor 220 forward but is not effective in retracting the rotor. However, rear bearing 250 in conjunction with the inner bearing retainer 280 is effective to impart a withdrawing motion from the housing 210 to the rotor 220. The rearward motion of housing 210 is imparted through radial bearing 250 to the outer circumferential portion of bearing retainer 280. The inner circumferential portion of bearing retainer 280 is fastened to rotor 220 by means of bolts 281 (FIG. 1) and is therefore effective to withdraw the rotor 220. Thus a withdrawing action of the thrust cylinders 80 is effective to withdraw cutting wheel 300 from the tunnel face.

The main drive shaft is hollow (FIGS. 4, 5, 8) thus permitting a center drill drive shaft 410 to pass through its entire length. A separate drive motor 420 mounted on gearbox (FIG. 2) drives the center drill drive shaft 410 relative to the movable frame 110. A center drill bearing assembly 450 (FIG. 8), which is generally similar to the main bearing assembly 200, supports the center drill 400 to be driven by the center drill drive shaft 410.

More specifically, the center drill bearing assembly 450 includes a rotor 460 having on its rearward end the male portion 461 of a splined coupling. The female portion 411 is attached to the forward end of drive shaft 410. The splined coupling permits a longitudinal sliding relationship between drive shaft 410 and rotor 460. The forward end of rotor 460 projects beyond the hub 310 of the main cutting wheel and provides a hub or base for attachment of the center drill 400.

Center drill bearing assembly 450 also includes a housing 470 that is received within a forward recess 227 formed in the rotor 220, and rotates with the rotor 220. Lugs 471 (FIG. 3) attached to the forward end of housing 470 are received in small circumferentially spaced recesses in the hub 310. Bolts 472 which pass through the lugs 471 permit housing 470 to slide longitudinally relative to rotor 220. Thus the housing 470 of the center drill bearing assembly rotates with rotor 220 of the main bearing assembly, while the rotor 460 is directly driven by shaft 410.

Rotor 460 is supported for rotation relative to housing 470 by a front radial bearing 480 and a rear radial bearing 490, and while the structure of these radial bearings is not identical to the structure of

radial bearings

240 and 250 their operation is nevertheless very much the same. A front bearing retainer 482 is attached around hub 462 and extends to the forward end of housing 470 so as to protect radial bearing 480 from dirt. A thrust bearing 485 is located intermediate to the

radial bearings

480 and 490, and its structure and function are very much like that of the thrust bearing 230 which was previously described. That is, forward thrust received from the housing 470 is imparted through thrust bearing 485 into rotor 460 and hence into the center drill 400.

In accordance with the preferred usage of the machine the main cutting wheel 300 is driven at a relatively slow rate, such as 10 revolutions per minute, while the center drill 400 is driven at a more rapid rate, such as 30 revolutions per minute. By reversing motor 420 the center drill 400 may, if desired, be rotated opposite to the main cutting wheel.

The center drill bearing assembly 450 also includes a preloading mechanism which has no counterpart in the main bearing assembly 200. The rotor 220 has a cylindrical recess 227 formed in its forward end (FIG. 8), and the depth of the recess 227 is considerably greater than what is necessary to accommodate the housing 470 of the center drill bearing ansemhly. The prcloading assembly generally designated as 500 includes a forward plate 501 which is of generally circular configuration, but having a central opening through which the female coupling 411 extends. The preloading assembly 500 also includes a generally circular rear plate 502. A plurality of bolts 503 are spaced about the circumferences of the two

plates

501, 502 and are utilized to retain these plates in proximity to each other. The plate 502 has a central opening which surrounds the drive shaft 410, but not in direct engagement with it, so that drive shaft 410 is permitted to rotate relative to the plate 502. To the rear of recess 227 the rotor 220 is further recessed, with smaller diameter opening, in order to permit the pilot drill drive shaft 410 to be received therein. Thus the recess 227 forms a circumferential shoulder which faces in a forwardly direction within the rotor 220. The outer circumfer ential edge of plate 502 bears against this circumferential shoulder and thus provides the basis for supporting center drill 40 for forward thrust. The inner circumferential portion of plate 502 is recessed on its front side so as to receive a set of Belleville disc springs 504. The springs 504 push the plate 501 forward relative to the plate 502, but the total displacement is limited by the bolts 503. The forward surface of plate 501 bears tight against the rearward end of housing 470 (except for a bearing retainer therebetween).

The entire housing 470 of the center drill bearing assembly 450 is free to slide longitudinally, to some extent, relative to the rotor 220 and hub 310. Lugs 471 are welded to the housing 470 and hence move with the housing. Bolts 472 are firmly retained in threaded openings in the rotor 220 and in the hub 310, but the openings through which they pass in the lugs 471 are not threaded, hence the lugs 471 may slide rearwardly a limited distance relative to the bolts 472.

The purpose of the preloading assembly 500 is to permit the center drill 400 to retract under excessive load. For example, when the machine is built with a cutting wheel diameter of 13 feet and is designed for a total thrust of 1 million pounds against the tunnel face, for cutting material which has a compressive strength of 30,000 pounds per square inch, the design load for the center drill 400 is then 90,000 pounds of forward thrust. The preload assembly 500 is then set to this load value of 90,000 pounds, and in the event the center drill receives a load in excess of that amount it will move rearwardly a small distance relative to the main cutting wheel 300, thus minimizing the shock on the center drill and protecting it against damage.

The preloading is accomplished by placing the springs 504 under a compressive stress of 90,000 pounds and then tightening the bolts 503 so that the

plates

501, 502 will retain the springs in their compressed condition. A gap 505 between

plates

501, 502 would permit further compression of the springs 504. However, under normal operating conditions the thrust load on the center drill is 90,000 pounds or less, hence the springs 504 are not required to accept any additional compression and the gap 505 does not close even partially. But if an overload for the center drill is encountered then that overload will be picked up by the springs 504, and the center drill together with its bearing assembly 450 will be permitted to retract relative to the main cutting wheel. Lugs 471 will move rearwardly relative to hub 310 and the gap 505 will commence to close.

For purpose of moving the machine into and out of a tunnel, and transporting it, it is necessary to disassemble the main cutting wheel 300. With reference to HO. 4, there is illustrated a removable spoke 330 of the main cutting wheel, which can be detached from the central portion of the cutting wheel simply by removing a number of bolts. This illustrated detail is typical of the cutting wheel construction and indicates the manner in which the entire cutting wheel may be disassembled for convenience in transportation.

It is possible to remove and replace both the main bearing assembly 200 and the center drill bearing assembly 450 in a very limited time, such as two or three hours where an overload crane and other shop equipment are available, or perhaps 2 or 3 days under conditions which prevail inside a tunnel. The procedure for removing and replacing these two bearings will now be briefly described.

First the entire machine is retracted from the tunnel face, a distance of about l0 feet. Then the center drill 400 and its bearing assembly 450 are removed. This is accomplished simply by removing the nuts from the bolts 472, and the entire housing 470 together with the associated preload assembly 500 slides out of recess 227 of the rotor 220. The splined coupling 461 41 1 simply separates.

The next step is to remove the main cutting wheel 300. This is done by removing bolts 222 (FIG. 7). The hub 310 then simply slips off the forward end of rotor 220. The next step is to expand the thrust cylinders so as to move the movable frame about two feed forward from its most rearwardly position. Access can then be obtained to the bolts 211, of which in the presently preferred form of the machine there are 48 spaced about the periphery of the front guide tube ring Thereafter, the bolts 88 are removed and the thrust cylinders 80 are retracted so as to draw the thrust collar 85 rearwardly. It is then possible to pull the main bearing assembly 200 in a forwardly direction and remove it from contact both with the guide tube flange 117 and with the thrust collar 85. The female gear may then be detached from rotor 220 by removing the bolts 221.

As a convenience in performing these operations it is desirable to provide a small rearward extension (not shown in the present drawings) on thrust collar 85. This extension serves to support the thrust collar 85 from the guide tube ring 117 both during and after the time when the bolts 211 are removed. Another desirable convenience is a platform which can be positioned in front of the machine to receive the main bearing assembly 200 when it is removed.

The female drive gear 155 may be attached to the replacement main bearing unit, which can then be inserted into the machine by following the reverse of the procedure described above. After the main bearing assembly has been replaced a new pilot drill bearing assembly is inserted, again by following the reverse of the described procedure.

What is claimed as new is:

l. A tunneling machine comprising:

a main support frame having front and rear sets of telescoping legs adapted for outward extension to grip the tunnel wall;

a movable frame which is supported within the main support frame in nonrotative but longitudinally movable relationship thereto;

a generally circular cutting wheel at the forward end of the machine;

a drive shaft carried within the movable frame and rotatable relative thereto for imparting rotating drive to the cutting wheel;

rotating drive means carried on the movable frame for drivingly rotating the drive shaft;

a main bearing assembly including a stator having a generally hollow cylindrical configuration, a rotor disposed within said stator, and bearing means supporting said rotor for rotation relative to said stator;

said drive shaft terminating rearwardly of said main bearing assembly and said rotor having its rearward end removably coupled to said drive shaft and its forward end removably coupled to said cutting wheel, said stator having its rearward end coupled to the forward end of said movable frame;

and forward thrust drive means carried on the main support frame and drivingly coupled to said stator for advancing the cutting wheel, movable frame, and drive shaft whereby the rotating drive from said rotating drive means is concurrently imparted through said drive shaft and said rotor to said cutting wheel.

2. A tunneling machine as claimed in claim 1 which includes auxiliary shoes cooperatively associated with the front and rear ends of said movable frame for supporting both frames when the main support frame is being advanced to a new position within the tunnel, and wherein the front auxiliary shoe is attached to said stator of said main bearing assembly.

3. A tunneling machine as claimed in claim 1 which includes removable bolts attaching said rotor to said cutting wheel, attaching said rotor to a drive gear coupled to said drive shaft, and attaching said stator to said movable frame.

4. A tunneling machine as claimed in claim 1 which includes a female drive gear removably attached to the rearward end of said rotor by means of bolts, and a male drive gear attached to said drive shaft, said drive gears being relatively slidable longitudinally of said drive shaft.

5. A tunneling machine as claimed in claim 1 which includes a mating pair of driving gears which drivingly couple said rotor to said drive shaft, one of said driving gears being attached to said drive shaft and the other of said driving gears being attached to said rotor, said gears being slidable relative to each other along the longitudinal axis of the drive shaft whereby longitudinal vibrations imparted from the cutting wheel to the rotor are not transmitted to said rotating drive means.

6. A tunneling machine as claimed in claim 1 wherein the couplings of said rotor to said drive shaft and to said cutting wheel are arranged for easy detachment, and wherein the couplings of said stator to said movable frame and to said forward thrust drive means are also arranged for easy detachment, whereby said main bearing assembly may be easily removed and replaced in its entirety.

7. A tunneling machine as claimed in claim 6 which includes a mating pair of driving gears which drivingly couple said rotor to said drive shaft, one of said driving gears being attached to said drive shaft and the other of said driving gears being attached to said rotor, said gears being slidable relative to each other along the longitudinal axis of the drive shaft whereby longitudinal vibrations imparted from the cutting wheel to the rotor are not transmitted to said rotating drive means.

8. A tunneling machine as claimed in claim 1 wherein said bearing means includes separate radial bearings disposed between said stator and rotor at their forward and rearward ends, respectively, and a thrust bearing disposed between said stator and rotor intermediate their ends, said thrust bearings being retained between an interior thrust collar of said stator having a forwardly facing thrust shoulder and an exterior thrust collar of said rotor having a rearwardly facing thrust shoulder.

9. A tunneling machine as claimed in claim 8 wherein said radial bearings include cylindrical bearing members, and said thrust bearing also includes cylindrical bearing members disposed perpendicular to the bearing members of said radial bearings.

10. A tunneling machine as claimed in claim 8 wherein the couplings of said rotor to said drive shaft and to said cutting wheel are arranged for easy detachment, and wherein the couplings of said stator to said movable frame and to said forward thrust drive means are also arranged for easy detachment, whereby said main bearing assembly may be easily removed and replaced in its entirety.

11. A tunneling machine as claimed in claim 10 which includes a mating pair of driving gears which drivingly couple said rotor to said drive shaft, one of said driving gears being attached to said drive shaft and the other of said driving gears being attached to said rotor, said gears being slidable relative to each other along the longitudinal axis of the drive shaft whereby longitudinal vibrations imparted from the cutting wheel to the rotor are not transmitted to said rotating drive means.

12. A tunnel machine as claimed in claim 8 which includes a mating pair of driving gears which drivingly couple said rotor to said driver shaft, one of said driving gears being attached to said drive shaft and the other of said driving gears being attached to said rotor, said gears being slidable relative to each other along the longitudinal axis of the drive shaft whereby longitudinal vibrations imparted from the cutting wheel to the rotor are not transmitted to said rotating drive means.

13. A tunneling machine comprising: a main support frame having front and rear sets of telescoping legs adapted for outward extension to grip the tunnel walls a movable frame supported within the main support frame in non-rotative but longitudinally movable relationship thereto;

a drive shaft supported by the movable frame in rotatable relationship thereto;

rotating drive means carried on the movable frame for drivingly rotating the drive shaft,

a main bearing assembly including a stator having a generally hollow cylindrical configuration, a rotor disposed within said stator, radial bearing means supporting said rotor for.rotation relative to said stator, and thrust bearing means for driving said rotor forward when said stator moves forward;

said stator having its rearward end removably coupled to the forward end of said movable frame;

said drive shaft terminating rearwardly of said main bearing assembly, and said rotor having its rearward end removably coupled to said drive shaft;

a generally circular cutting wheel at the forward end of the machine, removably coupled to the forward end of said rotor;

and forward thrust drive means carried on the main support frame and drivingly coupled to said stator for advancing the bearing assembly, drive shaft, movable frame, and cutting wheel while a rotating drive is concurrently imparted from said rotating drive means through said drive shaft and said rotor to said cutting wheel;

the attachment of said stator to said forward thrust drive means being also removable whereby said main bearing assembly may be detached as a complete unit from the remainder of the tunneling machine.

14. A tunneling machine as claimed in claim 13 which includes a mating pair of driving gears which drivingly couple said rotor to said drive shaft, one of said driving gears being attached to said drive shaft and the other of said driving gears being attached to said rotor, said gears being slidable relative to each other along the longitudinal axis of the drive shaft whereby longitudinal vibrations imparted from the cutting wheel to the rotor are not transmitted to said rotating drive means.

15. A tunneling machine as claimed in claim 13 which includes a plurality of removable bolts coupling the rearward end of said rotor to said driving shaft and a plurality of removable bolts attaching said stator to said movable frame.

16. A tunneling machine as claimed in claim 13 wherein said cutting wheel and said rotor have a centrally located recess formed therein, and which further includes a center drill disposed at the center of said cutting wheel and in front of said recess, and resilient support means disposed within said recess and attached to said center drill for drivingly supporting the same.

17. A tunneling machine as claimed in claim 16 wherein said resilient support means includes spring means compressible in a direction perpendicular to the plane of said cutting wheel, and means confining said spring means in a compressed condition at a predetermined initial force level.

a: i i

Claims

1. A tunneling machine comprising: a main support frame having front and rear sets of telescoping legs adapted for outward extension to grip the tunnel wall; a movable frame which is supported within the main support frame in nonrotative but longitudinally movable relationship thereto; a generally circular cutting wheel at the forward end of the machine; a drive shaft carried within the movable frame and rotatable relative thereto for imparting rotating drive to the cutting wheel; rotating drive means carried on the movable frame for drivingly rotating the drive shaft; a main bearing assembly including a stator having a generally hollow cylindrical configuration, a rotor disposed within said stator, and bearing means supporting said rotor for rotation relative to said stator; said drive shaft terminating rearwardly of said main bearing assembly and said rotor having its rearward end removably coupled to said drive shaft and its forward end removably coupled to said cutting wheel, said stator having its rearward end coupled to the forward end of said movable frame; and forward thrust drive means carried on the main support frame and drivingly coupled to said stator for advancing the cutting wheel, movable frame, and drive shaft whereby the rotating drive from said rotating drive means is concurrently imparted through said drive shaft and said rotor to said cutting wheel.

8. A tunneling machine as claimed in claim 1 wherein said bearing means includes separate radial bearings disposed between said stator and rotor at their forward and rearward ends, respectively, and a thrust bearing disposed between said stator and rotor intermediate their ends, said thrust bearing being retained between an interior thrust collar of said stator having a forwardly facing thrust shoulder and an exterior thrust collar of said rotor having a rearwardly facing thrust shoulder.

12. A tunneling machine as claimed in claim 8 which includes a mating pair of driving gears which drivingly couple said rotor to said drive shaft, one of said driving gears being attached to said drive shaft and the other of said driving gears being attached to said rotor, said gears being slidable relative to each other along the longitudinal axis of the drive shaft whereby longitudinal vibrations imparted from the cutting wheel to the rotor are not transmitted to said rotating drive means.

13. A tunneling machine comprising: a main support frame having front and rear sets of telescoping legs adapted for outward extension to grip the tunnel walls; a movable frame supported within the main support frame in non-rotative but longitudinally movable relationship thereto; a drive shaft supported by the movable frame in rotatable relationship thereto; rotating drive means carried on the movable frame for drivingly rotating the drive shaft; a main bearing assembly including a stator having a generally hollow cylindrical configuration, a rotor disposed within said stator, radial bearing means supporting said rotor for rotation relative to said stator, and thrust bearing means for driving said rotor forward when said stator moves forward; said stator having its rearward end removably coupled to the forward end of said movable frame; said drive shaft terminating rearwardly of said main bearing assembly, and said rotor having its rearward end removably coupled to said drive shaft; a generally circular cutting wheel at the forward end of the machine, removably coupled to the forward end of said rotor; and forward thrust drive means carried on the main support frame and drivingly coupled to said stator for advancing the bearing assembly, drive shaft, movable frame, and cutting wheel while a rotating drive is concurrently imparted from said rotating drive means through said drive shaft and said rotor to said cutting wheel; the attachment of said stator to said forward thrust drive means being also removable whereby said main bearing assembly may be detached as a complete unit from the remainder of the tunneling machine.