US3292715A

US3292715A - Earth drilling machinery

Info

Publication number: US3292715A
Application number: US366338A
Authority: US
Inventors: Roy O Balogh
Original assignee: MCCABE POWERS BODY Co
Current assignee: MCCABE POWERS BODY Co
Priority date: 1964-05-11
Filing date: 1964-05-11
Publication date: 1966-12-20
Anticipated expiration: 1983-12-20

Description

Dec. 20, 1966 R. o.Y BALOGH 3,292,715

EARTH DRILLING MACHINERY m INVENTOR.

yam o. BALOGH LKJBYWMT ATTORNEY A DCC 20, 1966 R. o. BALOGH 3,292,715

EARTH DRILLING MACHINERY Filed May 11, 1964 4 Sheets-Sheet 2 Flc. 5 y

INVENTOR.

ROY O. BALO GH ATTORNEY Dec. 20, 1966 R. o. BALOGH EARTH DRILLING MACHINERY 4 Sheets-Sheet 5 Filed May 1l, 1964 FIG. 7

INVENTOR. ROY O. BALOGH A AT TO RNEY -DeC- 20, 1966 R. o. BALOGH EARTH DRILLING MACHINERY 4 Sheets-Sheet 4 Filed May 1l, 1964 FIG. 8

ROY O. BALOGH FIG. IO

AT TORNEY United States Patent O 3,292,715 EARTH DRILLING MACHINERY Roy 0. Balogh, Ladue, Mo., assignor to McCabe-Powers Body Company, St. Louis, Mo., a corporation of Missouri Filed May 11, 1964, Ser. No. 366,338 19 Claims. (Cl. 173-12) This invention relates in general to cert-ain new and useful improvements in earth drilling machinery, and, more particularly, to a portable hydraulically driven earth auger which is uniquely suitable for drilling post holes and the like.

In the use of portable earth drilling tools such as earth augers, it becomes necessary to impose downward axial pressure upon the tool and to supply a reasonably uniform amount of torque to drive the tool under Widely varying load conditions. For example, :an earth auger may initially encounter easy digging near the surface and progressively more diflicult digging at greater depths Where the soil is more rocky o1- heavily compacted. In many instances, it is necessary to reverse the tool :and lift it out of the hole when the tool becomes stuck or jammed. Conventional prime movers which tend to run at constant speed, will, of course, be comparatively inecient except in a narrow range of optimum load conditions and, in fact, will tend to stall under load conditions which are only moderately excessive. For this reason, many types of manually changeable or so called shiftable transmissions have been devised, but such transmissions are expensive to manufacture, costly to maintain, and somewhat difficult to operate effectively. In fact, changes in load conditions often occur so quickly and unexpectedly that the average operator cannot shift gears so to speak, in suiiicient time to prevent stalling. Moreover, such devices cannot be conveniently used with boom-supported units having power-actuated means for raising and lowering the tool with respect to the hole and with respect -to stored or transport position.

It is, therefore, the primary object of the present invention to provide an earth auger which is lifted, positioned, and rotarily driven by hydraulic means and is, therefore, particularly well adapted to the drilling of post holes for utility poles, telephone poles, and the like.

It is another object of the present invention to provide an earth auger of the type stated which is capable of transmitting substantially constant power under widely varying drilling conditions, and is also capable of being driven axially downwardly into the ground, or lifted up out of the ground by hydraulic means.

It is a further object of the present invention to provide lan earth auger having a driving motor which automatically adjusts the torque output to meet variations or uctuations -in load conditions.

It is an additional object ofthe present invention to provide a hydraulically driven earth auger of the type stated which is compacted, rugged, and durable.

It is also an object of the present invention to provide a hydraulically driven earth auger of the type stated which is entirely portable and can be readily supported in various work-positions at the end of a boom or similar supporting structure.

With the above and yother objects in view, my invention resides in the novel features of form, construction, arrangement, and combination of parts presently described and pointed out in the claims.

In the accompanying drawings FIG. 1 is a side elevational view of an earth auger unit constructed in accordance with and embodying the present invention, the vehicle upon which such unit is mounted being shown in dashed lines;

Patented Dec. 20, 1966 FIG. 8 is a fragmentary sectional view taken along lines 8 8 of FIG. 7;

FIG. 9 is transverse sectional View taken along lines 9 9 of FIG. 8; and

FIG. 10 is a fragmentary sectional view taken along lines 10-10 of FIG. 9.

Refering now in more detail and by reference characters to the drawings which illustrate a preferred embodiment of the present invention, A designates a conventional utility vehicle shown in dotted lines and having the usual workbody 1 mounted Ion the chassis 2 to the rear of the cab 3. l

Rigidly secured upon the work-body 1, preferably at the upper rear left corner, is a turntable-mount 4 which supports a -base h'ousing 5 for rotation about a vertical axis. The base housing 5 is provided with an oil-driven motor 6 which operates some type of worm or pinion upon a stationary ring gear so as to rotate the entire base housing 5 in either direction. The latter elements are entirely conventional and, therefore, are not specically illustrated or described in detail herein.

Swingably mounted at its lower or base-supported end, upon the base housing 5, is a boom 6 formed of a tubular shell member having rectangular cross-sectional shape and having a longitudinally extensible hydraulic motor or ram 7 which is pivotally secured at one end thereto and extends angularly downwardly therefrom, being also pivotally secured at its other end to the base housing 5. By this means, the angular position yof the boom 6 can be varied as required.- The internal construction and hydraulic circuit to the ram 7 are also conventional and, therefore, not specifically illustrated or described in detail herein.

Welded -or otherwise rigidly secured upon the outer end of the boom 6 is a laterally projecting bracket 8 having a horizontal hinge pin 9 for Swingably supporting an earth auger generally designated by the reference number 10 and comprising an upper support casting 11 integrally including a circular base plate 12 and an upstanding open-topped collar 13 of substantially rectangular cross-sectional shape so as to have a box-like configuration, and integrally formed with two opposed parallel walls as a continuation thereof are somewhat

triangular flanges

14, 15, having

coaxial apertures

16, 17, respectively, for accommodating the hinge pin 9.

In this connection, it should be noted that for convenience of illustration in FIG. 4, the earth auger is shown in vertical or operative position, but it can be disposed in any position. In fact, the earth auger 10 is usually swung up into a somewhat horizontal or sto-called transport position shown in FIG. 1 when not in actual use, and supported in such position by a carrying bracket b and clamping dog d as shown in FIG. 3.

Bolted together in vertically stacked relation upon the underside of the base plate 12 by means of long tie-bolts 18 which engage threaded holes 19 in base plate 12 is an upper circular end plate 20, an upper stationary ring-gear 21, a cylindrical housing sleeve 22, a lower ring gear 23, and a lower circular end plate 24, thereby forming a wholly enclosed gearing chamber c1. As may be seen by reference to FIG. 7, in addition to the bolts 18, the end plate 20 and upper ring gear 21 are held in stationay position in relation to the base plate 12 and to each other by means of

pins

25, 26, respectively. The lower end plate 24 is conveniently provided with a filling aperture 27,' and a drainage aperture 28, respectively, closed by

plugs

29, 30. The upper end plate 20 is integrally provided with an upwardly projecting coaxial collar 31 which projects through and is snugly seated in the bottom wall 32 of the base plate 12.

The lower end plate 24v is also centrally provided with an integral bearing sleeve 33 having an internal annular shoulder 34 which supports two roller-

thrust bearings

35, 36, respectively, having

stationary races

37, 38, sets of rollers 39, 40,

retainer rings

41, 42, and

rotary races

43, 44, the latter being fitted tightly upon the threaded end f a main shaft 45, and held by a shaft nut n, the latter being threaded up against a cupped annularV washer 46, and the lower rotary race 44 to adjustth'e seating of the

bearings

35, 36. The main shaft 45 extends through conventional rotary oil seal 47 which is mounted concentrically in a collar 48 secured up against the under face of the lower end plate 24 by bolts 49. The main shaft 45 extends downwardly through and below the collar 48 for a substantial length and is provided with a helical cutting blade or bit 150, all =as best seen in FIG. 4.

The upper or internal end of the main shaft 45 is diametrally enlarged to provide an abutment shoulder 51 for the upper rotary race 43 and is integrally provided with a diametrally enlarged lower cage 52 which carries three uniformly spaced vertical journal pins 53 which are locked in position by pins 54 and are located at 120 intervals with respect to each other. Rotatably mounted upon the journal pins 53 by means of needle bearings 55 are planetary spur gears 56 which externally mesh with the ring gear 23 and internally with a sun gear 57 rigidly mounted in and projecting coaxially downwardly from an upper cage 58. Interposed between the under face of the sun gear 57 and the upper face of the cage 52 is a thrust collar 59 formed of oil impregnated sintered bronze or similar material and held in concentric position by a boss 60 formed on the cage 52.

The upper cage 58 carries three uniformly spaced vertical journal pins 61 which are locked in place by pins 62 and are located at 120 intervals with respect to each other. Rotatably mounted upon the journal pins 61 by means of needle bearings 62' are compound planetary gears 63 having an upper spur gear 64 which meshes with the ring gear 21 and a lower spur gear element 65 which meshes with a driving gear 66, the lower end of which is bearinged upon a thrust collar 67 seated in the upper end of the sun gear 57. At its upper end, the driving gear 66 is socketed .and connected by means of a key 68 to the projecting end of a drive shaft 69 forming part of a hydraulic motor M which is secured to the upper face of the collar 31 by means of bolts 70.

The motor M comprises a cylindrical housing 71 consisting of a lower case 72, an upper case 73, and a cap plate 74 held together in oil tight stacked relation by the bolts 75, thereby forming an enclosed motor chamber c2. The drive shaft 69 is journaled between upper and lower sets of roller-

thrust bearings

76, 77, and 78, 79, which are substantially the same as the previously de-` scribed set of

roller thrust bearings

35, 36. Between the sets of

roller thrust bearings

76, 77, and 78, 79, the drive shaft 69 passes rotatably through a stationary distributor plate 80 and a stationary cylinder block 81, the shaft 69 being sealed with respect to the former by three lower'O-rings 82, and to the latter by two upper O-rings 82. i The distributor plate 80 is sealed to the lower case by two O-rings 83 and is held rigidly against an abutment shoulder 84 by means of bolts 85. The distributor plate 80 has radial ducts or

passages

86, 87, bored therethrough for communication with the high-

pressure oil lines

88, 89, and with axially spaced

annular manifold channels

90, 91, turned in the outer face of the drive shaft 69. These

manifold channels

90, 91 open to the lower ends of

axial ducts

92, 93, which are drilled upwardly through the i 4 drive shaft 69 and at their upper ends open to

arcuate distributor channels

94, 95, each extending for for about 170 of lthe arcuate distance around the drive shaft 69 as best seen in FIG. 9.

The cylinder block 81 is provided with six uniformly t spaced axially extending cylinders, which, for convenienceof reference, are designated 96a, 96h, 96, 96d, 96e, 96f. It will, Iof course, be understood that more or less than six cylinders may be employed. Each of the cylinders 96B, 96h, 96, 96d, 96e, 96f, open downwardly to the chamber c2, and is internally provided with reciprot cating pistons 97 operatively sealed by piston rings 98;

Each piston 97 is provided with a downwardly projecting piston rod 99 having a conventional wobble bearing 100` mounted on its lower end for operatively riding in a groove 101 formed in the upper face of a wobble plate 102, which is rockably secured to the drive shaft 69 by a diametral pin 103. The Cylinders 96 open at their upper ends to radial oil ducts 104r which extend inwardly through the cylinder block and communicate with the

distributor channels

94, 95. Thus, as shown in FIGS. 8

and 9, the cylinders 968', 96h, and 96, are open to pressure.

as the piston 97 of the cylinder 96's is just beginning to` move down. Similarly, the cylinders 96d, 96e, and 96f,

are open to return as the piston 97 of cylinder Y96f is just beginning to move up. This supplies torque to the drive shaft 69 causing it to rotate and as the drive shaft 69 rotates, the

distributor channels

94, 95 rotate also causing the several pistons 97 to move up and down in a properly timed cycle.

The upper end of the drive shaft 69 is concentrically bored to provide a servo-cylinder 105 which is closed at its upper end. At its lower end, the servo-cylinder 105 is provided with a pair of diametrally opposed radial. slots 106 for accommodating a shiftable pin 107 which extends outwardly therethrough and is engaged in a control ring 108V slidably mounted on the drive shaft 69.

Welded or otherwise rigidly secured to the control ring 108 and extending axially downwardly therefrom is a rocker bar 109 which is operatively secured by means of a pin 110 to a boss 111, integrally formed on the wobbleplate 102. Internally within the lower end of the cylinder` 105, the pin 107 is mounted in and extends diametrally through a cylindrical plug or follower 112, which is biased upwardly by a compression spring 113. On its upper4 flat face, the plug or follower 112 abuttingly bears against the lower polished end of a tubular piston-rod or quill 114 which extends operatively through a transverse wall 115 and O-rings 116. The cylinder 105 is further provided with an intermediate wall 117 and, consequently, is subdivided, by the wall 115 and rings 116 into an intermediate chamber c3, a lower chamber c4, and lan upper chamber c5, the chambers c3 and c5 respectively communicating through

small bore ducts

118, 119, 120, to the

distributor channels

94, 95, as shown in FIG. 10, thereby z being connected to the pressure and return

lines

88, 89.

At its upper end, the quill 114 is rigidly secured ooncentrically upon the under side of a servo-piston 121, which is provided with an O-ring 122,and is operatively disposed within the intermediate chamber c3. Moreover,

the intermediate wall 117 is integrally provided on its 1 under face with a depending concentric tubular sleeve 123, the lower end of which is located in a plane .slightly below the plane of the inlet opening or small bore duct. 118, and acts as a 'stop abutment limiting the upper travel of the servo-piston 121.

Extending snugly, but nevertheless slidably, through the quill 114 and the servo-piston 121, is an auxiliary piston-rod 124, which also projects upwardly from the servo-piston 121, and extends-slidably through the tubular sleeve 123 and into the upper chamber c5, wherein it is rigidly secured concentrically upon the under face of an auxiliary servo-piston 125 having an O-ring 126, and being operatively disposed for movement upwardly and` downwardly within the chamber c5.

At its extreme upper end, the servo-cylinder 105 is preferably closed by a threaded plug 127 which is integrally provided on its under face with a concentric depending boss 128, having a downwardly presented ilat abutment face 129 which is located in a plane slightly below the plane of the small bore duct 120, the abutment face 129 serving as a stop for limiting the upward movement or travel of the auxiliary servo-piston 125. The length of the auxiliary piston-rod 124 in relation to the quill 114, and the other dimensions of the servo-cylinder 105, are such that when the auxiliary servo-piston 125 is shifted to its lower position within the chamber c5, the lower end of the auxiliary piston-rod 124 will abut the follower 112 and push it downwardly against the bias of the compression spring 113 to a lower limit of travel and, accordingly, the control ring 108 will be shifted to a lower position of travel, so that the wobble plate 102 will assume a position of maximum angularity. Similarly, the length of the quill 114 is such that when the servo-piston 121 is shifted downwardly to its lower limit of travel, the lower end of the quill 114 will bear abuttingly against the follower 112 and will also push the follower 112 downwardly to the same lower limit of travel so that the wobble plate 102 will, in turn, be shifted to the same position of maximum angullarity. Thus, it will be evident that either the quill 114, or the auxiliary piston-rod 124, are capable of causing the wobble-plate 102 to move to a position of maximum angularity. This change of angle n the wobble-plate 102 changes the amount of reciprocation of the piston 97, and causes the main shaft 45 to speed up or slow down as the case may be, so that the power delivered to the m-ain shaft 45 remains substantially constant.

Disposed concentrically around the quill 114 and extending axially through the lower portion of the intermediate chamber c3, between the upper face of the transverse wall 115 and the under face of the servo-piston 121, is a relatively strong compression spring 130, which will normally shift the servo-piston 121, and its associated quill 114, upwardly into abutment against the sleeve 123, or in other words, to the uppermost limit of travel whenever the upper portion of the chamber c3 above the servopiston 121 is not under positive pressure. Moreover, the strength of the spring 130 is selected with reference to the maximum and minimum limits of oil pressure supplied to the system from a conventional remotely located constant-ow oil pump (not shown), which will be present within the cylinders 96a, 96h, 96, 96d, 96e, 96f, under conditions of maximum and minimum torque, respectively, with reference to the load supplied to the main shaft 45.

When the oil line 88 is connected to the high pressure side of the system, and the oil line 89 is connected to the low pressure or return side of the system, by a remotely located conventional two-way control valve (not shown), so that oil flows into the system through the line 88 (as shown by the arrow in FIG. 8), the duct 92 will be under pressure and the motor M is so constructed that, under this condition, the main shaft 45 will be rotated in a direction which Will cause the tool or bit 50 to bore or dig into the earth. Under this condition, also, the portion of the chamber c3 above the servo-piston 121 will be under pressure and, accordingly, the servo-piston 121 will move upward land downward against the bias of the spring 130 to compensate for fluctuations in pressure which result from changes in load-conditions encountered by the t-ool or bit 50. In other words, as the load increases and the torque is required to turn the shaft 45, the pressure will tend to rise and, correspondingly, the servo-piston 121 will move downwardly, thereby increasing the angularity of the wobble-plate 102 with the result that the motor M will rotate at lower speeds and have a higher torqueoutput.

Where the load conditions are light, the pressure in the system will be minimal and, consequently, the servo-piston 121 will rise to the upper limit of its travel and the wobbleplate 102 will assume a position of minimum angularity under which conditions, the motor M will have maximum speed and minimum torque-output. This latter controlcondition is not only desirable for light load conditions, but is also useful after the tool or bit 50 has been removed from a drilled hole in the earth and it is desirable to spin :off adhering lumps of clay or dirt.

When the position of the control valve is reversed, so that high pressure is applied to the system through the other oil line 89, and the oil line 88 becomes the return line, the upper portion of the intermediate chamber c3 above the servo-piston 121 is, of course, at low pressure and the spring 130 will, accordingly, push the servo-piston 121 up to its upper limit of travel. Thereupon, the Wobble-plate 102 and its associated control ring 108, will tend to shift into the position of minimum angularity under influence of the spring 113. However, high pressure oil will now ilow through the axial duct 93, and small bore duct 120, to the upper portion of the chamber c5. Since the lower portion of the chamber c5, below the auxiliary servo-piston 125, is connected by the small bore duct 119, to the axial duct 92 and is, therefore, at low pressure, the auxiliary servo-piston will be shifted positively downward to its lowermost position of travel and the auxiliary piston-rod 124 associated therewith, will push the follower 112 down to the lowermost position of its travel. Consequently, the wobble-plate 102 will be shifted into the position of maximum angularity. It will, thus, be apparent that when the direction :of rotation of the main shaft 45 is reversed, the motor M will rotate at minimum speed and maximum torque-output, without compensation or variation. This is extremely necessary and useful in order to back the tool or bit 50, :out of the hole or back it oif in case a subterranean obstruction is encountered, or if the tool becomes jammed in heavy clay or highly compacted earth which may be encountered somewhere below the surface of the ground.

Of course, the motor M may be `conventionally controlled by an auxiliary manual control valve (not shown). Thus, when the earth auger 10 is lowered into the ground and set to run at some desired speed, it will automatically adjust itself to maintain substantially constant power over a wide lrange of varying load conditions. One important aspect of the present invention resides in the fact that, when the earth auger 10 is pulled up out of the hole being dug, and is fully clear of the hole, the load drops virtually to zero. Thereupon, the drive shaft 69 and main shaft 45 rotates very rapidly and spins the excess dirt from the blade, thereby completely cleaning it so that the earth auger 10 is either ready for the next drilling operation or for disposition in transport position as circumstances require.

It should be understood that changes and modifications in the form, construction, arrangement, and combination of the several parts of the earth drilling machinery may be made and substituted for those herein shown and described without departing from the nature and principle of my invention.

Having thus described my invention, what I claim and desire to secure -by Letters Patent is- 1. A portable earth auger comprising a main shaft, a boring tool on one end of the shaft, a motor connected to the opposite end of the shaft, said motor being adapted to supply substantially constant power to the main shaft at varying torques and angular velocities, control means operatively associated with the motor for sensing the resistance encountered by the boring tool and for automatically changing the torque and velocity of the shaft in response to such changes in resistance so that the boring tool rotates at substantially optimum velocity and torque, a constant ow pump, and conduits interconnecting said motor and pump.

2. An earth auger as dened in claim 1 in which the motor is a hydraulic motor.

3. An earth auger as defined in claim v1 in which a speed reducing gear train is operatively interposed between the shaft and the motor.

4. An earth auger as defined in claim 1 in which a planetary speed reducing gear train is operatively interposed between the shaft and motor.

5. An earth auger as defined in claim 1 in which the motor is a hydraulic motor of the wobble plate type.

6. An earth auger as defined in claim 2 in which the control means senses slight variations in the pressure of the hydraulic fluid in the motor, such pressure variations being caused by variations in the resistance encountered by the boring tool.

7. A portable earth auger comprising a main shaft, a boring tool on one end of the main shaft, a reversible oil-hydraulic rotary prime mover means operatively connected to the other end of the shaft, and control means adapted to maintain the prime mover at substantially constant power and varia-ble speed and torque when rotating in one direction and at maximum torque and minimum speed when rotating in the opposite direction.

8. An earth auger as defined in claim 7 in which the prime mover contains an adjustable angle wobble plate, and a plurality of circumferentially spaced pistons which act upon the wobble plate and rotate the same.

9. An earth auger as defined in claim 8 in which the prime mover includes a driven shaft which carries the wobble plate, the driven shaft having an axial Ibore, an axial piston and rod slidably mounted in the bore and operatively connected to the wobble plate for adjusting the angle of the wobble plate, and means for applying oil pressure against said axial piston, which pressure fiuctuates in substantially direct proportion to variationsrin the oil pressure to the prime mover.

10. An earth auger as defined in claim 8 in which the prime mover is a rotary reversi-ble hydraulic motor and includes a driven shaft which carries the wobble plate,

said driven shaft having an axial bore transversely subdivided into upper, lower and intermediate cylinders,`

a spring biased follower shiftably mounted in the lower cylinder and operatively connected to the wobble plate for adjusting the angle of inclination thereof with respect to the driven shaft, a first servo-piston in the intermediate cylinder for shifting the position of the follower when the motor is rotating in one direction, and another servo-piston in the upper cylinder for shifting the position of the follower when the motor is rotating in the other direction.

11. An earth auger is defined in claim 7 in which a speed reducing gear train is operatively interposed between the shaft and prime mover.

12. An earth auger as defined in claim 7 in which a planetary speed reducing gear train is operatively interposed lbetween the shaft and prime mover.

13. An earth auger comprising a main shaft; a boring tool mounted on one end of the main shaft; and a reversi-ble rotary hydraulic motor of the wobble plate type connected to the opposite end of the shaft, said motor comprising means for automatically reducing speed and increasing torque responsive to increase in load, which means include a driven shaft having an axial bore transversely subdivided into upper, lower and intermediate cylinders, a spring biased follower shiftably mounted in the lower cylinder and operatively connected to the wobble plate for adjusting the angle of inclination thereof with respect to the shaft, a first servo-piston in the intermediate cylinder for shifting the position of the follower when the motor is rotating in one direction and another servo-piston in the upper cylinder for shifting the position of the follower when the -motor is rotating in the other direction.

14. An earth auger comprising a main shaft; a boring tool mounted on one end of the main shaft; and a reversible rotary hydraulic motor of the wobble plate type connected to the opposite end ofthe shaft, said motor comprising means for automatically reducing speed and increasing torque responsive to increase in load, which mediate cylinder for shifting the position of the follower when the motor is rotating in one direction and another servo-piston in the upper cylinder for shifting the position of the follower to an extreme limit position when the motor is rotating in theother direction.

15. A hole digging unit for use with vehicles, said unit comprising in combination, a turntable adapted to be operatively mounted upon the vehicle, a housing rotarily mounted on the turntable for movement about an upright axis, power means for rotating the housing about said upright axis, a boom swingably mounted upon the housing for swinging movement about a substantially horizontal axis, power means for swinging the boom about said substantially horizontal laxis, an earth auger swingably mounted on the boom and including a main shaft, a boring tool on its fone end, a reversible oil-hydraulic rotary prime mover means operatively connected to the other end of the main shaft, and control means operatively associated with the prime mover means for varying the torque delivered to the main shaft responsive to the resistance encountered by the boring tool, said control means increasing the torque and decreasing the velocity of the main shaft when increased :resistance is encountered, and decreasing the torque and increasing the velocity of the main shaft when lower resistance is encountered.

n 16. A hole digging unit for use with vehicles; said unit comprising a hydraulic pump carried by the vehicle; a turntable-mount securely mounted on the vehicle; a housing rotatably carried by the turntable-mount for rotation about an upright axis; first power means for rotating the housing about the upright axis; a boom swingably carried by the housing for rotation about an axis perpendicular to the upright axis; second power means operatively connected to the housing and boom for swinging the boom with respect to the housing; an earth auger swinga-blysimultaneously increasing the torque supplied thereto when greater resistance is encountered; and conduit means interconnecting the hydraulic pump and motor.

17. A hole digging unit according to claim 16 in which the motor is reversible.

18. A hole digging unit according to claim 16 in which the hydraulic pump is a constant-flow pump.

19. An earth auger adapted for use with a hydraulic pump, said auger comprising a main shaft;a boring tool mounted on onerend of the main shaft; and a hydraulic motor connected to the opposite end of the main shaft, said motor comprising a housing, a drive shaft journaled in the housing and outwardly connected to the main shaft, an annular wobble plate pivotally secured to the drive shaft in encircling relation thereto, a cylinder block carried by the housing and having a plurality of circumferentially spaced cylinders disposed in encircling relation to the drive shaft and in axially spaced relation toy Vthe wobble plate, pistons slidably fitted into the cylinders and adapted to act upon the wobble plate, conduit means connected with the pump for introducing fluid into the cylinders in sequentially timed relation whereby the pistons move to-and-fro in the cylinders and rotate the wobble plate, control means for changing the angular position of the wobble plate with respect to the drive shaft whereby the stroke of the pistons, the torque applied to the drive shaft, and the speed of the drive shaft are varied, the control means being adapted to sense slight pressure variations in the conduit means caused by Varying torsional resistances encountered by the boring tool so as to increase the strike of the pistons when the pressure rises and to decrease the stroke of the pistons when the pressure lowers, whereby, when the boring tool meets increased resistance, the motor will supply greater torque at lower speeds and when the boring tool is free of the hole the motor will rotate it at relatively high speeds and spin oif excess material adhering to i-t.

References Cited by the Examiner UNITED STATES PATENTS Carrie et al. 74-60 Dilg 103-173 Harris 103-162 Dunlap 74-60 Sturrock 173-12 Swift 103-162 Attebo et a1. 173-12 Horton 10S-173 FRED C. MATTERN, JR., Primary Examiner.

MILTON KAUFMAN, Examiner. 15 L. P. KESSLER, Assistant Examiner.

Claims

1. A PORTABLE EARTH AUGER COMPRISING A MAIN SHAFT, A BORING TOOL ON ONE END OF THE SHAFT, A MOTOR CONNECTED TO THE OPPOSITE END OF THE SHAFT, SAID MOTOR BEING ADAPTED TO SUPPLY SUBSTANTIALLY CONSTANT POWER TO THE MAIN SHAFT AT VARYING TORQUES AND ANGULAR VELOCITIES, CONTROL MEANS OPERATIVELY ASSOCIATED WITH THE MOTOR FOR SENSING THE RESISTANCE ENCOUNTERED BY THE BORING TOOL AND FOR AUTOMATICALLY CHANGING THE TORQUE AND VELOCITY OF THE SHAFT IN RESPONSE TO SUCH CHANGES IN RESISTANCE SO THAT THE BORING TOOL ROTATES AT SUBSTANTIALLY OPTIMUM VELOCITY AND TORQUE, A CONSTANT FLOW PUMP, AND CONDUITS INTERCONNECTING SAID MOTOR AND PUMP.