US3386769A

US3386769A - Rock-breaking apparatus

Info

Publication number: US3386769A
Application number: US519364A
Authority: US
Inventors: Howard A Wilmeth
Original assignee: WHITE PINE COPPER CO
Current assignee: WHITE PINE COPPER CO
Priority date: 1966-01-07
Filing date: 1966-01-07
Publication date: 1968-06-04
Anticipated expiration: 1985-06-04

Description

June 4, 1968 H. A. WILMETH ROCK-BREAKING APPARATUS 6 Sheets-Sheet 1 Filed Jan. '7, 1966 m NAM Ta WW W4 4 %W H 4 i 5 7 w H Ham June 4, 1968 A. WILMETH 3,386,769

ROCK*BREAKING APPARATUS Filed Jan. 7, 1966 6 Sheets-Sheet, 2

H-af

J/ I n F INVENTOR.

Hon/4&9 4-. n MMEM 5Z BY.

I w I June 4, 1968 H. A. WiLMETH 3,386,769

ROCK-BREAKING APPARATUS Filed Jan. 7, 1966 v 6 Sheets-Sheet 4 Q- INVENTOR. HOW/1R0 A. a; 445 71 m R BY June 4, 1968 H. A. WILMETH 3,386,769

ROCK-BREAKING APPARATUS Filed Jan. 7, 1966 6 Sheets-Sheet 5 LE 5m F/GJQ A 2/ 4 INVENTOR.

Han 4&0 4. M/(Mf/A H. WiLMETH ROCK BREAKING APPARATUS 6 sheets sheet 6 Filed Jan. '7, 1.966

NVENTOR.

United States Patent 3,386,769 ROCK-BREAKING APPARATUS Howard A. Wilmeth, White Pine Copper (10., White Pine, Mich. 49971 Filed Jan. 7, 1966, Ser. No. 519,364 9 Claims. (Cl. 299-79) This invention relates to apparatus for breaking solid rock as is necessary in either surface or underground mining operations.

The apparatus of the invention aims to provide a rockbreaking machine or mining machine which is capable of directly breaking the rock where solid rock is encountered without the necessity of blasting, which is both expensive and hazardous, not only from the effects of the explosive, but also from the effects of noxious fumes which must be cleared from the area after a blasting operation. The apparatus of the invention aims, by means of a single operation, to eliminate the drilling and blasting operations and the clearing away of noxious fumes.

In accordance with the invention, the breaking of the rock is accomplished by means of a controlled and combined impacting and ripping action. The apparatus of the invention is provided with a ripper which includes a bit and tooth assembly, that is, a tooth structure that encloses a bit which is advanced through the rock by an impacting action produced by an impacting apparatus or mechanism, and the rock between the tooth and free surface of the rock formation is sheared away by the wedging action of the ripper tooth which supports the bit and which advances behind the bit.

The apparatus of the invention is mounted on either a drawn vehicle or a self-powered vehicle, such for example, as a tractor. The apparatus includes a supporting housing which is mounted upon, and advantageously pivoted to, a mounting boom carried by a vehicle such as a self propelled tractor. Arranged to be slidable longitudinally in the supporting housing, there is a ripper housing or bit and tooth assembly on the forward end of which the ripper tooth and bit are mounted. In one form of the apparatus the impacting mechanism includes at least one resonance tube which extends through the bit and tooth assembly, and a vibrating mechanism at the rear end thereof. Such resonance tube is filled with an incompressible liquid, and an anvil member is mounted in movable, fluid-tight relation at each end.

The anvil member at the rear is acted upon by the vibrating mechanism. The anvil at the front end of this resonance tube acts upon the shank of the bit to impart impacting blowsto the bit. The vibrating mechanism is associated with a control member and is movable thereby into and out of engagement with its cooperating anvil, and is resiliently held out of engagement therewith.

The entire bit and tooth assembly is urged forward towards the rock to be broken by a suitable resilient means, such as a hydraulic cylinder to which fluid pressure is supplied. When the tractor moves the bit into engagement with the rock the vibrating mechanism first is moved by relative movement between the control member and bit and tooth assembly into engagement with the resonance tube anvil. Following this the entire bit and tooth assembly moves rearwardly in the supporting housing by the force of the tractor in pressing the bit against the rock. The frequency of the blows imparted by the impacting mechanism is regulated or varied until it corresponds with the natural frequency of longitudinal vibration of the column of liquid in the resonance tube. This results in causing the bit to impart rock-breaking blows against the surface of the rock thus causing the bit to rip through the rock. The rock material between the bit and the free surface of the rock is sheared away by the wedging action ice of the ripper tooth advancing conjointly and simultaneously behind the bit by the thrust of the hydraulic cylinder and of the tractor.

The above description refers only to a single resonance tube, bit and impacting mechanism, whereas ordinarily the ripper housing will contain two or more resonance tubes with their associated bits and impacting mechanisms, the bits being arranged with their cutting edges in alignment with one another and usually in vertical or upright position.

In another form of the apparatus instead of employing the resonance tube impacting mechanism described above, a percussion tool, that is, a fluid pressure-operated reciprocating impacting mechanism may be used to subject the bit to rapidly repeated impacts. The percussion tool is mounted in fixed position within the bit and tooth assembly with its bit shank in operative engagement with the shank of the bit of the bit and tooth assembly. As in the resonance type of impacting mechanism, a control member is arranged to be shiftable lengthwise with respect to the bit and tooth assembly to start and stop the operation of the percussion tool. The operation of this embodiment of the invention is the same as described previously.

It is intended that where the mining conditions require it, two or more impact-ripper apparatuses such as described above may be mounted on the same tractor. In this way a plurality of cuts may be made in the side of a rock wall, for example a vertical wall. The thrust of the hydraulic cylinder of each aparatus will maintain the bit in contact with the rock even under changing rock conditions. That is to say, the rock formation at different levels may have diiferent characteristics as to hardness or brittleness, and by means of the hydraulic cylinders, the bits of all of the impact rippers will be maintained in operation, within the range of the strokes of the hydraulic cylinders.

Among the other advantages of the invention are that the power required for advancing the bit is less than is required to advance a ripper point without the impacting action; that the impacting action is produced by a power source which is separate from that which provides the tractive power for the vehicle so that the entire vehicle tractive power is available for shearing the rock out of place; and that the apparatus of the invention is capable of performing the rock-breaking as a continuous operation.

The invention will be better understood from a consideration of the accompanying drawings and the description following.

In these drawings:

FIGS. 1-7 illustrate one embodiment of the invention;

FIG. 1 is a perspective view of a tractor carrying impact-ripper apparatus of the invention;

FIG. 2A is a plan view of the impact-ripper mechanisrn in its normal, extended position;

FIG. 2B is a view similar to FIG. 2A with parts in different positions;

FIG. 3 is a view in vertical longitudinal section of the impact-ripper mechanism and the upper end of the tractor boom, taken on broken line 33 of FIG. 213;

FIG. 4 is a view in horizontal section taken on line 4-4 of FIG. 3 and drawn to an enlarged scale;

FIG. 5 is a transverse vertical section taken on line 5--5 of FIG. 28 showing the impacting mechanism;

FIG. 6 is a vertical transverse section taken on broken line 66 of FIG. 3; and

FIG. 7 is a diagrammatic view of a fluid pressure control valve and its connections;

FIG. 8 is a plan view somewhat similar to FIG. 28 to illustrate a modified form of resonance tube;

FIGS. 9 and 10 illustrate another embodiment of the impact-ripper apparatus of the invention, FIG. 9 being an exploded view in perspective, and FIG. 10 being a partial horizontal section taken on line 10-1tl of FIG. 9.

Referring to FIGS. 1-7:

FIG. 1 shows a rock breaking apparatus which is indicated generally by reference numeral 10 mounted at the upper end of a boom 11 of a self-powered tractor which is indicated generally by reference numeral 12. This tractor may or may not have a front loading scoop as shown, but uprights 13, or other suitable structures are added to the tractor frame in order to support and control the boom. Boom 11 is shown as being pivoted at its lower end on a shaft 14 which is mounted at its opposite ends in the uprights 13. The apparatus 10 is pivotally mounted on the outer end of boom 11 and arrangements are made as will be presently described for adjusting the apparatus to maintain it in approximately horizontal position as boom 11 is raised or lowered. One or more additional booms such as the one shown in phantom may be added to carry additional impact ripper apparatus if desired.

The raising and lowering of boom 11 are accomplished by means of a hydraulic cylinder 15 which is pivoted at its outer end between the upper portions of uprights 13, and the piston rod 16 which is suitably pivoted to the boom. It is desirable to be able to adjust the boom 11 laterally in order to place apparatus 10 at the desired lateral position with respect to the tractor. This may be accomplished in any desired manner, as by means of two sets of segmented spacers 17 and 18, one set being disposed on each side of boom 11 on the shaft 14. Each set of these spacers is preferably composed of two semicircular segments. The two half sections may be secured together by bolts and nuts or screws as indicated. It will be understood that a change in the lateral position of the boom on shaft 14 is effected by removing the two sets of spacers and replacing them with spacers of different lengths.

The apparatus 10 comprises a supporting housing 28, a bit and tooth assembly 21 including bit impacting mechanism, and a control member 22 in the form of a casing for a part of the impacting means. A ripper tooth structure 23 is secured to the front or left-hand end of the bit and tooth assembly 21 by means of a number of long screws 24 one of which is shown in dotted lines in FIG. 4. Tooth structure 23 is dimensioned in the vertical direction to carry two bits, that is, lower and upper bits 25. The cutting edges of these bits are in vertical alignment with one another. Bits 25 have cylindrical shank portions 26 which slide freely and have limited horizontal movement in suitable apertures in tooth structure 23. The bits are held in position by means of set screws 27.

Supporting housing 20 is a rectangular shell-like structure open at the front as may be seen in FIG. 6- and having a rear Wall 28, an upper wall 29 and front lower and upper flanges 30 which project toward one another in the same plane. Bit and tooth assembly 21 is rectangular in cross section (FIG. 6) and arranged to slide lengthwise or horizontally on the interior surfaces of housing 20, the surfaces of rear wall 28 and top wall 29 being grooved in order to allow the escape of dust which necessarily collects on apparatus operated in a mine atmosphere.

At its lower portion supporting housing 20 is provided with downwardly and forwardly projecting ear portions 31 (FIG. 3) between which a pivot member 32 extends by which the carriage is secured to boom 11. The forward ends of ears 31 extend a short distance in front of housing 20 as shown in FIGS. 2A., 2B and 3. In order to support the rear portion of housing 2t) and also to adjust the horizontal position of the housing about pivot 32, a hydraulic cylinder 33 is provided. This cylinder is pivoted at 34 to boom 11, and the outer end of its piston rod 35 is pivoted at 36 to housing 20.

In this form of the invention the impacting mechanism comprises resonance tubes and vibrators, and extending from end to end of the bit and tooth assembly 21 are two resonance tube bores, that is, lower and upper bores 37.

These bores or passages are disposed in angular position horizontally (FIG. 4) because shanks 26 of bits 25 are near one side of assembly 21 Whereas the impacting mechanism to be described is located near the opposite side. Because of this arrangement and in order to save weight bores 37 are placed in elongated fonmations 38 in the assembly 21, rectangular in cross section as show in FIG. 6. Assembly 21 is provided with a front cover plate 39 which is secured to the body of the assembly by means of cap screws two of which are shown in dotted lines in FIG. 6.

The resonance tube bores 37 are each provided with rear anvil assemblies 40 (FIG. 3) and forward anvil assemblies 41. The rear anvil assemblies have anvil members 42 and the forward anvil assemblies have anvil members 43. These four anvil assemblies are alike and one of them is shown in detail in FIG. 4. Each comprises an anvil member 42 or 43 which is threaded into a collar 44, the collar being a close sliding fit in a mounting cylinder 45 which is externally threaded and received within a threaded aperture forming an enlargement at the adjacent end of bores 37.

The inner end of collar 44 has an internal conical surface and a flexible gasket member or seal 47 of special shape as shown in FIG. 4 has a conical portion which lies against this internal coned surface and it also has a second conical surface which is disposed in contact with the coned inner end surface of mounting cylinder 45. An expanding spring ring 4% maintains the outer conical portion of the gasket in contact with mounting cylinder 45, and a contracting spring ring 49 serves a similar purpose with respect to the inner conical portion of the gasket. The inner ends of anvil members 42 and 43 are enlarged to the full diameter of resonance tube bore 37.

By this construction the anvil members 42 and 43 respectively are maintained in contact with and in fluidtight relationship with their respective ends of the resonant tube bores and at the same time these anvil members are permitted to move longitudinally to a small extent.

The anvil members 43 at the front ends of the resonance tubes cooperate with the inner ends of shanks 26 of the two bits 25. For this purpose these anvils are in their normal positions slightly spaced from the inner ends of the shanks.

The anvil members 42 at the rear ends of the resonance tube bores 37 are acted upon by cam members 50 of the vibrating mechanisbm 54 which cams are in the form of spherical balls mounted in uniformly spaced relationship around the periphery of upper and lower rotary discs 51. These rotary discs are fixed to horizontal lower and upper shafts 52 and are supported in the back compartment 53 of the vibrating mechanism casing 22. Shafts 52 are supported for rotation in suitable ball bearings 55 as indicated in FIG. 5. For rotating each of the shafts 52 there are lower and upper driving motors 52a (FIG. 5). These motors are disposed in the front compartment 56 of casing 54 and are secured by means of bolts 57 to the outer wall 58 of casing 54.

Cam members 50 are supported in hollow cylindrical externally threaded members 50a (FIG. 4) which are screwed into threaded radial openings which are uniformly spaced around the cylindrical periphery of each of the rotary discs 51. The hollow cylinders 50a are constricted at their outer ends to retain the cams 50 therein. These cams are free to move radially within the respective hollow cylinders and are thrown outwardly under the rotating action of the discs. A damping coil spring 5012 is placed within the cam assembly to absorb the rebounding cam after it strikes anvil 42.

Casing 22 which constitutes the control member of vibrating mechanism 54- is mounted for limited horizontal sliding movement on four round supporting rods 59 two of which are shown in dotted lines in FIG. 4 and also in FIG. 3. These rods are threaded at their inner end portions and screwed tightly into threaded apertures in the rear end of bit and tooth assembly 21. The purpose of such sliding mounting of casing 22 is to enable the free earns 50 to be normally held out of contact with their cooperating anvils 42. To accomplish this, casing or control member 22 is resiliently urged rearwardly or to the right by means of a small hydraulic cylinder 6%. Cylinder 6% is bolted to the outer wall 58 of casing 22. Piston 61 has a piston rod 62 which is permanently threaded into an aperture in bit and tooth assembly 21. Hydraulic fluid under constant pressure is supplied to cylinder 69 through a connection 63 which is at the right of piston 61. The purpose of this cylinder is to resiliently urge the vibrating mechanism 54 towards the right in FIG. 3, its casing 22 sliding on the supporting rods 59 and separating the cams 50 from anvils The entire bit and tooth assembly 21 including the vibrating mechanism 54-, ripper teeth 23 and bits 25 is urged toward the left in FIG. 3, that is, forwardly, by means of a long hydraulic cylinder 64 which is pivoted at 65 to the bottom of casing 22 of the vibrating mechanism 54. The piston rod 456 is pivoted at 67 to the lower portion of supporting housing 20. Hydraulic fluid for operating cylinder 64 enters through a connection d3. A control valve 69 for cylinder 64 is shown in FIG. 7. A pipe it! leads from this valve to connection 68 at the front end of cylinder 64. A supply pipe '71 delivers fluid under suitable pressure to the operating member of valve 69, and 72 is the exhaust conduit. Valve 69 is operated by means of a lever 73 which engages stop members 74 and '75 which are suitably mounted on bit and tooth assembly 21 (FIGS. 2A and 2B).

In order to permit the movement of the vibrating mechanism 54 towards the left in FIG. 2B, casing 22 has lower and upper rectangular slots or grooves 76 in order to clear the lower and upper flanges 30 of supporting housing 29 (FIG. 5). In FIG. 2B the upper groove '76 is shown just to the right of the upper flange 3i whereas in PPS. 2A bit and tooth assembly 21 and vibrating mechanism 22 have been moved to the left, or forward.

In 2A the tractor has not yet brought the teeth 2-5 into engagement with the rock, so that bit and tooth assembly 21 is in its normal position projecting to the left of supporting housing 2% Vibrating mechanism 54 and its control member 22 have been moved to a location within the right end portion of housing 20, this movement being permitted by the grooves '76 (FIG. 5) referred to in the previous paragraph. The mechanical force developed by air cylinder 64 which produces this movement is applied to bit and tooth assembly 21 by control member 22 through the small air cylinder 65) and its piston rod 62. The diameter of cylinder 60 is somewhat less than that of cylinder 64 so that, with the same air pressure applied to both cylinders, when the tractor places the teeth 25 against the rock to be broken as shown in FIG. 2B the thrust of the tractor causes the control member 22 with vibrating mechanism 54- and the bit and tooth assembly 21 to move relatively to each other until they are in contact with one another as shown in FIG. 3.

This starts the vibration of the liquid in resonance tubes 37 and the application of the impacting force to the rock by teeth 25. This starting of the impacting force occurs with both embodiments of the invention shown in the drawings, that is with the resonance tube form of FIGS. 18, and with the percussion form of FIGS. 9 and 10, as will be described below. The continued thrust of the tractor causes the bit and tooth assembly 21 and its vibrating mechanism 54 to slide rearwardly in supporting housing 26 from the position shown in FIG. 2A to that shown in FIG. 3, which is an intermediate position, and possibly to that shown in FIG. 23 if the tractor is advanced sufficiently far. Such movement takes place against the yielding, resilient force developed by hydraulic cylinder 64.

In operating the form of my rock-breaking apparatus shown in FlGS. 1-8, the vibration motors 52a are first started. These rotate the cam discs 51, and the free cams 50 are forced outwardly by centrifugal force. in such outward positions they will strike the impact anvils 42 after the control member 22 (with vibrating mechanism 5 and the tooth and bit assembly 21 have been forced. together in close contact as shown in both FIGS. 3 and 4.

The tractor 12 is operated to position the teeth 25 of bit and tooth assembly 21 as desired with respect to the rock to be broken for removing the desired depth of rock therefrom. The tractor is set in forward motion, that is, to the left in FIG. 1 and the ripper-teeth 25 encounter the rock. As described above, the movement of the tractor forces teeth 25 and assembly 21 backward into engagement with control member 22 and vibrating mechanism 54 which are held against backward movement by cylinder es and its piston rod 66. The rotating cams begin striking the impact 'anvils 4-2.

A control device for regulating the speed of the impact motors 52a is shown at 52b, and the rotative speed of these motors is adjusted until the frequency of the blows of cams 5% against anvils &2 corresponds with the resonance frequency of the liquid in the resonance tubes 37. As the first cam strikes each impact anvil 42 the impact force is transmitted through the anvil to the liquid within the tube and the force is transmitted by the liquid to the forward end of each resonance tube. A portion of the pressure wave that strikes each forward impact anvil 41 travels through the anvil and to one of the shanks 26 and bit 25.

A portion of the pressure wave is reflected from each anvil ll and travels back toward the rear end of each resonance tube. At the instant it arrives at each impact anvil 42 a reinforcing impact is delivered by the next cam 59 striking the anvil, and an amplified pressure wave now travels forward through each resonance tube. Periodically as the pressure wave becomes sufiiciently great, each forward impact anvil is violently oscillated. This oscillation is transmitted to the ripper-bits and supplies the impacting force to cause the bits to penetrate the rock. The tractive force of tractor l2 simultaneously advances the impact-ripper apparatus and plows the rock out of place.

FIG. 8 shows another embodiment of the impact-ripper and is a view somewhat similar to FIG. 2B but with the forward portion of bit and tooth assembly 21a shown broken away and in section. The purpose of this modification is to avoid placing the resonance tube or tubes at a horizontal angle with respect to the sides of the assembly. This is accomplished by employing one or more curved resonance tubes 37a, one tube being shown in FIG. 8.

The main portion '77 of this tube extends in parallel relation to the sides of the assembly 21a to the rear end of this assembly and is provided with an anvil member not shown) and with a control member 22 for the vibrating mechanism, both of which are in all respects similar to those described above. The forward portion 78 of resonance tube 37a is directed laterally into alignment with the axis of shank 26a of bit 25a. An anvil assembly 41a in all respects similar to that previously described mechanically interconnects the liquid within the resonance tube with the inner end of shank 25a. It will be understood that the supporting housing Zlla, cylinder 60a, and all other parts of the apparatus are similar to those described previously.

Referring now to FIGS. 9 and 10 these figures illustrate an embodiment of the impact-ripper in which, instead of employing resonance tubes and vibrating mechanism as the bit impacting mechanism, a percussion tool is used for this purpose. In these figures the bit and tooth assembly 21a is a box-like rectangular structure having a cover member 39a secured to its open vertical side by means of screws one of which is shown at '78. Assembly 21a is mounted for sliding movement in a supporting housing Ztla which may be constructed in a similar manner to housing 20, and which is to be supported on tractor 12, or other suitable vehicle, and may be mounted on boom 11 for rocking vertical movement as previously described and shown in FIG. 3.

At the right end of bit and tooth assembly 21a there is a control member 22a of casing-like form as is the control member for the apparatus of FIGS. 1-7. Member 22a is mounted for relative movement into and out of engagement with the right end of assembly 21a. Control member 22a is a continuation of the rectangular structure forming assembly Ella and is mounted for sliding lengthwise movement on upper and lower stationary horizontal rods 79 which project from the right end of cover member 3% and also from the opposite or back wall of assembly 21a. A cover member 80 for the control member 22a is secured to it by screws 81. Parallel apertures 82 in cover member 8d receive the front supporting rods 79, and similar apertures (not shown) receive the rear supporting rods '79, only one of which is visible.

A small air cylinder 66a is mounted on the right end of member 22a and is supplied with air under suitable pressure in the same way as cylinder as. A piston 61a and rod 62a are provided, and at its inner end this piston rod is fixed to member 22a in any suitable manner. As in the case of cylinder on, cylinder 69:: serves as a resilient biasing means to maintain, under normal conditions, the control member 22a separated slightly from the end of bit and tooth assembly 21a, as shown in FIG. 9.

In FIG. 9, the single bit member 83 shown is arranged for sliding movement in a ripper tooth structure 84. If desired the bit may be in two sections as in FIG. 3. Bit 83 has a cylindrical shank 85, and may be held in position by means of a set screw (not shown) as in the case of the two bit members of FIG. 3. Shank may extend through the front wall of tooth and bit assembly 21a as shown in FIG. 10. The percussion tool for impacting the bit is shown at 36 and may be of any desired construction such for example as is used in paving breakers.

Tool 86 comprises an air operated piston 87 which is arranged to slide lengthwise in the bore of a cylinder 88. Piston 87 is operatively associated with the inner end of shank member 89, and the outer end of this shank member engages shank 85 of the bit. The percussion tool shank 89 slides in an aperture in the front head 9d of the percussion tool, and this head is provided with an extension as shown in FIG. 10 which is received in an aperture 91 in the wall of bit and tooth assembly 21a. Tool 86 is secured in position within assembly Zia in any convenient manner (not shown).

The supply of air or other pressure fluid for operating the reciprocating impacting mechanism 86 is received through a conduit 92 which is connected to an electromagnetically operated control valve 93 mounted on cover member 80 of control member 22a. The outlet of valve 93 is connected through a conduit 94 to the inlet connection 95 for the impacting mechanism or tool 86. Inlet 95 is in the form of a straight pipe or tube which projects through an aperture in the right end wall of control or casing member 22a so as to allow this member to shift toward and away from the right end of assembly 21a as previously referred to.

The operation of electromagnetic valve 93 is effected by means of a source of electric energy which is connected to conductors 97 of this valve through a control switch 93 mounted as indicated in FIG. 9 on the right end of control member 22a by means of the screws shown. Switch Q8 has an operating member 99 which projects through an aperture in this casing and is actuated by the end of a rod tilt which is fixed to the inner wall of bit and tooth assembly 21a.

As in the form of the invention shown in FIGS. 1-7, the control member or casing 22a and the bit and tooth assembly 21a are urged or biased toward the left in FIG.

9 and in such manner as to be projected to the left of supporting housing 29a (FIG. 2A), by means of a long hydraulic cylinder 64a and piston rod 66a. The cylinder is connected by a pivot 55a to casing 22a and piston rod 66a is connected by pivot 67a to supporting housing 249a.

The operation of this form of the apparatus is similar to that of the apparatus shown in FIGS. 1-8. That is to say, cylinder 64a causes both the control member 22a and the assembly 2111 to be projected toward the left from the supporting housing 2 63a as shown in FIG. 2A, control member 22a however being maintained in separated position from assembly 21a by the small air cylinder ila (FIG. 9). When the bit 33 is moved by the tractor into engagement with the rock to be broken, relative movement between control member 2211 and assembly 21a occurs first and this forces the end of rod tea to the right to en age member 99 and close the contacts of switch -98.

This energizes electromagnetic valve 93 causing operating pressure fluid to be supplied to the reciprocating impacting mechanism or percussion tool 86. Continued and increased pressure of bit 83 against the rock forces assembly 21a and control member 22a farther to the right in housing 20a, the impacting of bit 33 continuing. As soon however as the pressure of the bit against the rock is released, control member 2211 is separated or moved to the right with respect to assembly 21a by cylinder 60a, thus opening switch 98 and stopping the operation of the impacting tool 8-6.

The bit and tooth assembly 21 of FIGS. 1-8 is forced forwardly against the rock by the hydraulic pressure within the long cylinder 64. A tractor thrust that is greater than the forwardly acting force of cylinder 64 causes control member 22, vibrating mechanism 54 and assembly 21 to move backward in the supporting housing 20. A tractor thrust that is less than the thrust of cylinder 64 will permit the cylinder to move mechanism 54 and assembly 21 forward in housing 20. The apparatus of FIGS. 910 operates similarly.

When tractor booms 11 and 11a carry a plurality of impact ripper apparatuses ill, ltla etc., the apparatus which is slowest to advance receives more thrust than can be delivered by its hydraulic cylinder 64. This occurs when its bit and tooth assembly 21 and vibrating mechanism 54 have been pushed back to the extreme rearward position.

At such time, a stop 71 (FIGS. 1 and 2B) on assembly 21 engages the end of housing 20 and prevents further backward movement. The fastest advancing

impact ripper apparatus

10, 10a etc., eventually reaches its most forward position in its supporting housing 20. Further forward movement is prevented by stop 74 (FIG. 7) shifting the lever 73 of valve 69 to the Off position, thereby cutting off further passage of hydraulic fluid to cylinder 64- and simultaneously providing for the discharge of the fluid within the cylinder. The lever 73 is re-positioned by the engagement of stop 75 and lever '73 when the bit and tooth assembly 21 moves in the opposite direction to its maximum rearward position.

As shown in FIG. 1 the booms 11 and as well as the impact ripper apparatuses It) and 10a extend toward the front of the tractor 12. The apparatuses Id and 10a are advanced against the rock to be broken by a pushing action of the tractor. If desired however, under certain conditions, the parts may be re-arranged so that apparatuses It} and 10a are brought into engagement with the rock by a pulling action of the tractor. This may be accomplished merely by reversing the position of each of the apparatuses It? and 1641 on their respective booms and operating the tractor in a backward direction. Also it may be accomplished by re-arranging the booms 11 and Illa so that they extend .rearwardly of the tractor, apparatuses lit? and Ida being reversed on the booms so that they point toward the front of the tractor, which will be operated in the normal or forward direction.

I claim:

1. A rock-breaking apparatus having a bit and tooth structure assembly for engaging the rock, the bit being arranged in sliding relation to the tooth structure, a supporting housing in which the bit and tooth structure assembly is slidably mounted, impacting means for continuously subjecting the bit to rapidly repeated impacts, means for yieldingly urging the bit and tooth assembly to move forward in the supporting housing, means for advancing the housing to place the bit in engagement with the rock to be broken and cause the bit and tooth assembly to move rearwardly with respect to the housing against the force of the yielding urging means, and means actuated by the said movement of the bit and tooth assembly for bringing the impacting means into operation.

2. A rock-breaking apparatus as set forth in claim 1 in which the impacting means includes at least one liquid-filled resonance tube having one end mechanically connected to the bit and having means operating on the opposite end thereof for causing the liquid column to vibrate at its natural period of vibration.

3. A rock breaking apparatus as set forth in claim 1 in which the impacting means is mounted at the rear end of bit and tooth assembly and in movable relation thereto, means being provided for yieldingly separating the impacting means from said assembly, and a hydraulic cylinder connected between the supporting housing and the impacting means for moving the impacting means into engagement with the bit and tooth assembly against the force of the yielding separating means and for moving both the impacting means and the ripper housing forward in the carriage assembly.

4. A rock-breaking apparatus having a bit and tooth assembly for engaging the rock, the bit being arranged in sliding relation to the tooth, a supporting housing in which the bit and tooth assembly is slidably mounted, a control member mounted in slidable and engageable relation with the supporting housing, impacting means associated with the bit and tooth assembly and said control member for continuously subjecting the bit to rapidly repeated impacts, means for yieldingly urging the control member to move into engagement with the bit and tooth assembly and then causing both to move forward in the supporting housing, means for advancing the housing to place the bit in engagement with the rock to be broken and thereafter to cause the bit and tooth assembly to move rearwardly in the housing against the force of the yielding urging means, and means operated by the control member for causing the operation of the impacting means.

5. A rock-breaking apparatus as set forth in claim 4 having means providing limited separating movement between the bit and tooth assembly and the control member, and also having means for resiliently urging these devices apart, the means for causing the operation of the impacting means being operated by the limited relative movement between the bit and tooth assembly and the control member for bringing the impacting means into and out of operation.

6. An impact-ripper mechanism comprising a supporting housing, a bit and tooth assembly mounted to slide lengthwise in the housing, the assembly including a resonance tube, forward and rear anvil members mounted for limited movement lengthwise of the tube and in fluidtight connection therewith at the opposite ends of the tube, a column of incompressible fluid within the bore and having its opposite ends in contact with the respective anvil members, a tooth structure secured to the forward end of the bit and tooth assembly, a bit having a shank portion slidable in an aperture in the tooth structure approximately in line with the tube, the inner end of the shank being approximately in contact with the forward anvil member, and means for impacting the rear anvil member at the resonance frequency of the column of liquid within the tube, which comprises a casing mounted for limited sliding movement at the rear end of the ripper housing, a rotary cam assembly within the casing having a plurality of cams for impacting the rear anvil member, a motor for rotating the cam assembly, and means for varying the speed thereof.

7. An impact-ripper mechanism as set forth in claim 6 wherein the rotary cam assembly comprises a rotor having radial apertures equally spaced around its periphery, each aperture having a ball-type cam member radially movable therein, restraining means associated with each aperture for holding the cam member on a predetermined radius under the action of centrifugal force at which radial position the cam member strikes the anvil.

8. An impact-ripper mechanism as set forth in claim 7 wherein each radial aperture of the rotor is provided with means for absorbing the rebound of the cam member after it strikes the anvil.

9. An impact-ripper mechanism as set forth in claim 6 in which the resonance tube has a main portion and at least one end portion which is angularly positioned with respect to the main portion, the bit having a shank portion slidable in an aperture in the tooth structure in line with the outer angular end portion of the tube.

References Cited UNITED STATES PATENTS 1,710,887 4/ 1929 Morgan 299 X 2,228,445 1/ 1941 De Velbiss 299-7O X 2,384,435 9/1945 Bodine -66 X 2,606,013 8/1952 Acker 29970 X 3,030,715 4/ 1962 Bodine 299-14 X 3,305,953 2/1967 Von Mehren et a1. l73l5 X ERNEST R. PURSER, Primary Examiner.