US1271275A - Expansive and contractive well-drill. - Google Patents

Description

0. M. CARTER. fxmwslvf AND @Mmmm/.f wm DRILL.

Patented July 2, 1918.`

U, M. CARTER. LXPANSLVL AND CONTRACLLVE WELL DRILL.

APPLICATEON FILED 1AN.5.IHU

'Patented July 2, 1918.

Arron/uns 0, NI. GA'RTER.

EXPANSIVE AND CONTRACTIVE WELL DRILL,

APPLfcAmm mio nur 5` 191e.

1 ,271,275. Patented July 2, 1918.

f 41 Y Y @M Q l TTORNEYS f y citizen of the United States, and a resident' oscar, maarncanraa., or HOUSTON, Texas.

A EXPANSIVE .AND-0N1RACTIVE WELL-DRILL.

Speeieatlon of Letters Patent. i

Patented July 2, 1918.

Application ledjanuary 5, 1918. Serial No. 210,536.

LTo all 'whom t may concern: Y

Be it known that I, `Oscar: M. CARTER, a

of Houston, in the county of Harris and State of Texas, have invented a new and useful Im rovement in Expansive and Contractive is a specification. l

My invention relates to improvements in well drills, being more particularly an improvement in' drills of the expansiveand contractivebit type, and it consists in the constructions, combinations and arrangements herein described and claimed.

An object of my inventionis to provide a drill of the type described, including as the essential feature a carrier casin having the expansive and contractive drill its mounted therein with rack platesY for extending the bits, said casin being adapted to be low- A ered into the drill stem and also to be raised out of operative position, without involving the danger of scarifying the well bore.

Another object of the invention resides in the provision of the latch which coperates with the rackl plates in locking the bit eX- tending pinions after they have been acted upon b the rack plates.

Anot er object of the invention is to provide novel means for directing a stream of water and mud against the drillbits, to keep them from becoming clogged.

Other objects and advantages will appear in the following specification, reference beingshad to the accompanying drawings in which:

Figure 1 is a lerspective view of the im- 'proved well' dri l, the carrier casing being shown in section, y

Fi 2 is a longitudinalsection taken sublstantially on the line 2 2 of Fig. 1,

Figs. 3, 4, 5, 6, 17,8 and 9 'are cross sec# tions on the lines 3 3, 4 4, 5 5, 6 6, 7 7, 8 8 and 9 9 of F1g. 1, y Fig. 410 is a side elevation showing the improved well drill at the bottom of the drill stem, and also showing the lowering tongs,

Fig. 11` isa vertical section of arts shown in Fig. 10, one of the carrier si e plates being removed,

Fig. 12 is a side elevation of the well drill, the carrier casing being omitted and the bits beingin the retracted position,

Fig. 13 is a detail side elevation of a p0rell-Drills, of which the following tion of the well drill illustrating the action of the cleansing stream. v

Fig. 14 is a detail perspective view of the carrier casing, l

Fig. 15 is a detail perspective view of the lower end of the'drill stem,

- Fig. 16 is a section on the line 16-16 of Fig.. 13, r

igs. 17 and 18 are detall perspective views of portions of the carrier casing,and Fig. 19 is a detail viewl illustrating vrthe raising tongs employed in' connection with the device.

In carryngyout y invention I rovide a drill stem 1 whiclqconsists of` a p urality of pipe sections joined together by couplings or by any other-suitable means, the drill stem havingan enlarged head 2 at the bottom, into which the drill bits 3 and 4 expand. The drill bits 3 and 4 are supported 1n a carrier casing 5. Racll plates 6 and- 7 are fixed in the carrier casi 5 by means "of screws 8 or some other simi ar means.

The rack plates 6 and 7 project beyond the upper edge of the carrier casing 5, and are so formed and arranged, that a latch 9 is 'movably disposed in the center of the body of the composite rack plates, the latch having a stem 10 provided with a head 11. by means of which the well drill is gripped by the lowering tongs shown in Fig. 10. Referring briefly to Fig. 10, it will be observed that the lowering tongs consist of a body 12 arranged at the top to receive the rope or cable 13 by means otwhich thedrill is lowered through the drill stem 1 to the bottom of the well. Amovel form of raising `tongs is also employed in connection with tl`e device These tongs are illustrated in Fig 19 and will presently be more fully explained.

The tong arms 14 are pivoted to the lower end of the body "12.* The upper portions of the arms are made comparativelylong and possess considerable weight. Whenthe well drill is lowered and reaches the proper position at thebottom of the stem 1, tension on the rope 13 is loosened,.whereupon the body 12 moves down, the weighted arms 14 move out, and the conical headallx` n the stern 10 is released. The lowern t' l,gs miy then los ,tensionl meshes with a inion 17, while the extension 16 meshes with apinion 18. Both pinions are mounted on ay shaft 19, supported i at its ends in carrier side plates 20.

A rack 21 is formed on top of each of a pair of bit holders 22 in which the bits 3 and 4 are secured by the bolts 23. VThe pinions 17 and 18 mesh with the racks 21 oi the respective bit holders, and are adapted to extend and retract the bits according to the direction-'of movement in either a downward or u ward direction, of the rack plates. The atch 9 simultaneously engages notches 24 and 25 inthe pinions 17 and 18, when the bits 3 and 4 are in the extended position shown in Fig. 1, and thereby lock the bitsv in this position during the operation of the drill.

The rack plates 6 and 7 are fastened t0- gether by screws 26 and thus form a composite body which is provided with a pas sage 27 in the center, in which the latch '9 slides. The latch 9 is the indirect control ling agent by which the extension and re` traction of the bits 3 and 4 is obtained. A dog 28 is virtually the connecting link between the latch and the rack plates, and by means of its coperative function 'with the latch, secures the shiftin of the rack plates ina certain portion of t ie movement of the latch. f

A. nose 29 is formed on the dog 28 near the pivot 30. i The nose 29 is disposed in the dog slot 31 formed at one side of the latch 9. The dog. 28 is located in a chamber 32 formed by cutting away adjacent portions of the composite rack plates, as clearly shown in Fig. 1. The dog 28 also has a mortise 33 at theeXposed end, into which a lever 34 is adapted to be itted'when it is desired to free the dog from its clamped engagement with the latch 9, as shown in Fig. 12. This feature will be more fully explained later.

Straps 35 bridge the separated portions of tlsgrackgplates, and ho d them together by virti of the screws which understood that the; rack plates are separated into the portions referred to, throu h the formation of the passage 27 in which the latch slides. The straps 35 are received in cut away portions 36 of the edges of the latch 9. l

A pin 37 disposed in a slot 3B in the latch 9, limits the up and down movement of the latch. The movement of the rack plates 6 and 7 is also limited by means'of pins 39 disposed in slots 40 of the portions of the respective plates.

The ccupancy of the pins 37' and 39in the slots 38 and 40 indicates that the latch 8, and the rack plates are adapted to be leked'up and down. As has been indicated,

lsite portions of thefheads ser "e the straps in place onlsaid portions. It will bel this movement of the latch and rack plates,

instance, and rotate thesame pinions 1n either one or the other direction, in the other instance. The bit holders 22 are extended When the rack plates move down, and the pinions are rotated correspondingly.

A rib 41 on each of the side plates 20, occupies a guide slot 42 in the companion bit holder. The bit .holders slide upon the ribs andalso keep the bit holders from dropping out of engagement with the pinions. Each bit holder has apeculiar shape, in that it includes an oset bracket 43, Wlich receives the bit, and in which the bit is secured by the bolts 23. The offset bracket 43 provides a shoulder 44 which abuts the lower edge of theside plate 2O thereby securing a more firm support for the bit holder, which further tends to keep the bitholder from oscillating on the side p1 te.

In this connectie the peculiar shape of the lower end of each of the side' plates should be observed. Attention is directed to Figs. 12 and 17. The side plate 20 has an enlar ed head 45 which in its formation on the p ate, provides a shoulder 46 abutting one corner of an Opening '47 of the carrier casin 5. This construction is clearly shown in Fig. 14. Referringl a ain4 to Fig. 17 it will be seen that the ea 45 is beveled at 48. The bevel occu ies approximately only one-half of the wi th of the head. O poof the side p ates are beveled. VIn other words the portion of the head in Fig. 17 nearest the observer, being beveled, the diametrically opposite ortion of the head of the other plate Wil be beveled.

The bevels 48 coperate in directing a stream of Water and mud under pressure against the bits 3 and 4. This stream is more forcibl directed by the aidLo/f.. similarly bevele portions 49 of closule plates 50 secured in thebottom of the carrier casing 5, by screws 51 or other means. The location of the closure plates is shown in Fig. 16, and one of the closure plates is illustrated in Fig. 18. The bevels '49 also occur at diametrically opposite points, so Vthat there may be one oi the bevels 49 opposite' each of the bevels 48 on the respective side plates 20. These beveled portions in o posing each other, form relatively narrow s its or orifices 52 through Which the water and mud flows at great pressure and s eed.

enlarged head 2 of the drill stern \1, support the carrier casing 5 as clearly shown in Fig. 16. The lugs include shanks which occupy recesses on the inside surface of the head and are secured therein by screws. The lugs'are sometimes broken ofi', and then the screws may be removed so that the remaining portion of the shank may be taken out drill stem.

. as shown in F1 the. drill stem.

and another lug put in its place. The lugs are made of some brittle material and are smaller where they join the Shanks, so as to facilitate breaking them off tiush with the inside of the enlarged head. This is done by dropping down a heavy weight with a rope attached to withdraw same so that a strainer of a smaller drill stem and bit may be 'passed through unimpeded and continue v the hole to a greater depth.

Slots 54 are cut into the lower edge of the drill stem head 2 and the upper edges of the slots are reinforced by bosses 55 which are cast on the outside of the head as shown in Fig. 15. The'slots 51 coincide with the openings 1i'l in the carrier casing 5. vThe outer portions of the bit holders 22 project into the slots 54 when the bits are in'the extended positions, and lock .the bits in place. This position of the arts is shown in Figs. 10, 11 and 13. Guide cams 56 are formed on the inside of the drill stem head 2, and occupy the surface between the slots, as clearly shown in Fig. 15.

The guide cams 56 guide the drill bits to the slotsJ 54. As the drill is lowered into the and when the drill bits which in the meantime become extended until they engage the surface of the drill stem, reach the enlarged head 2, they consequently become extended Still farther, ultimately reaching the guide cams Q6 and are thereby guided in either one or the other direction, to the slots 5l.

Fig. 19 formerly referred to, illustrates how a no'vel form of raising tongs is einplovedto withdraw the drill carrier from These tongs consist of the members 14'* pivoted together on the bottom of the body 12. A rope 13 is secured to the body. The free ends of ,the tong members 1l are formed into hooks 1lb which are` to grapple the conical head 11 on 10. It will readily be makes the members adapted the stem the nature of the tongs 14" drop to the normally closed position. lVhen the tongs are now lowered into the drill stem, the hooks 14h upon striking the head 11, will separate until upon pullin up on the tongs. they will engage the hea 19. Both forms of the tonrs illustrate(` in Figs. 10 and 19 have their particular value when used in connection with this particular form ot drill. As has previously been fully brought out the tongs illustrated in Fig. 10 are primarily adapted to lowering the drill. 1t will also be evident that the tongs in Fig 19 are primarilyadapted to raising the drill out of the drill stem.

The operation of the device is as follows: The tongs 14 grip the head 11 of the stem 10, and the drill is lowered into the drill stem 1 by the r0pe.13. Two distinct movements or actions now follow. The first acdrill is on the surface.

observed that` tion occurs after the dog 28 is tripped. The dog is tripped by inserting the lever 3l in the mortise .33, and pressing upward. The carrier`5 is thus lifted until the nose 29 of the dog slips entirely out of the dog slot 31. The gear racks ar(` then free to descend, partly expanding thebits so that they rub against the inside of the drill stem. carrier Tris further lowered until it rests on the lugs 53, whereuponby releasing tension on the rope, the bits expand to the fullest extent through the slots 54.

The second action occurs when the latch 9 is lowered to en age the alining notches 24 in the pinions 1 and 18. The carrier 5 and the bits now heilig in the final position, the carrier and the side plates 20 become the relatively stationary member. Further releasing of the rope permits the latch 9 to lower as described. The bits are now locked in the operating position.

Theaction of the dog '2S should also be understood. The dog is disposed in the po.- sition indicated in Fig. are in the retracted position and when the The nose 29 is disengaged from the dog slot 31 in the latch 9 by the use of the lever 34. An upward pressure on the lever first drives the latch 9 down a short distance in riding past the lower edge of the slot, but this having once een done, the weight of the carrier causes the carrier to descend a limited distance carrying the dog entirely below the dog slot. The nose of the dog is beveled on top,-and this beveled surface is adapted to lie parallel with the latch passage to enable the dog slot 31 in the latch 9 to move to a position beyond the dog. There is now perfect freedom between the latch and the bit carrier during the descent. The descent of the carrier is limited by the engagement of the bits with the inside of the drill Stem as formerly explained, and the function of the rack plates 6 and 7 remain latent until the outlets of the bits Vare reached when they drop by gravity. The spring QSE* holds the dog in the normal position. The dog is pivoted off center' and `will ordinarily assume the normal position by gravity. But to obviate the possibility of sticking, the spring 28 is made to bear on top of the dog and thus insure the proper working of the dog.

' The real function of the dog 28 is porformed principally when the drill is withdrawn from the drill stem. The occupation by the nose 29 of the dog slot 31 makes the two part motion of the latch 9 and the rack plates 6 and 7, possible. ln withdrawing the drill from the drill stem, the rope 13 is pulled upon until the lower edge of the nose engages the base of the slot 31. So much of the initial action serves to withdraw the end of the latch 9 from engagement with the The` 1-2, when the bits y alining slots 24 of the pinions, so that they are free to rotate as will presently appear.

he nose 29 now forms a solid connection between the rack plates and the latch. A continued pull on the rope 13 now serves to move ,the rack plates upwardly, so that the rac extensions l5 and 16 rotate the pinions 17 and 18, and consequently retract the bits 3 and 4. It now follows, that since the bits are encompassed by the carrier casing, the entiredrill may be withdrawn from the drill stem, until it reaches the surface.

It will be observed that the slot 38 in the latch 9 is longer than the slots 40 in the rack plates. This extra length of the slot 38 is necessary 'to ermit the two part motion just describe Returning briefly to the manner oi'` clearing the bits of matter during operation, water forced down the inside of the drill stem, and passes through the orifices 52 under great pressure against the sides of the bits as indicated by the arrows in Fig. 16, whereupon the water and mud stream returns to the top of the well on the outside of the drill stem 1.

This action of the water and mud leads to a consideration of one ofthe important features of the invention. The mud naturally seals the crevices and rough places in the surface of the bore of the well, but in instances where drills are used which have projecting portions, the sides of the bore are scarified on withdrawing the drilling tool.

moments consideration will make it evident that the sides of the bore cannot be injured when the type of tool illustrated in the awings is employed. The tool is withdrawn on the inside of the drill stem and consequently does not come in contact with the bore.

Incidentally the edges of the carrier casing 5 are beveled or possibilit of catching, when lowering the rill. Wliile the construction and arrangement of the device as illustrated in the accom anying drawings is that of a generally pre erred form, obviously modifications and changes may be made Without Vdeparting from the spirit of the invention or the scope of the claims.

I claim 1. A drill, including a carrier casing having extensible bits, adapted to be lowered into a drill stem with slots in the end, and gravity operated means carried by and rendered latent to extend the bits, before introducing the drill into the stem, said means urging the bits against the wall of the stem during the act of lowerin and becoming active to extend the bits w en the slots are reach LV B5 2. In a drill, a cable including gripping means for supporting the drill, extensible bits embodied in the drill, gravity operated ing extensible rounded to prevent the means for extending the bits, and releasable means normally restraining the gravity operated means.

, 3. A drill, including a carrier casing havbits, adapted to be lowered into a drill stem with slots in the end, means carried by and rendered latent to extend the bits, before introducing the drill into the stem, said means urging the bits against the wall of the stem during the act of lowering, becoming active to extend the bits when the slots are reached, and independently movable means carried by the carrier casing, providing the attaching member for receiving a lowering tongs, being ca able of move ment with respect to said l means upon bemg released, to lock the in the extended positions. j

4. In a drill, extensible bits, gravity operated means for extendingthebits, means for enga g and locking said means u arrival oltlhe bits in the extended 0sit1on and means for simultaneously gui ing and supporting the bits.

5i In a drill, extensible bits, means op ated by gravity for extending the bits, means operated by gravity for locking said means and preventing the bits from retracting while said locking means`is `in engage-- ment with the bit extending means.

In a drill, a drill stem with slots, a carrier casing occu yin an operative position at the bottom o sai drill stem, bits carried by the carrier casin and extended through the slots, means or retractin the bits through the slots, means provi ing an attaching member for a raisin tongs and locking the bits in the exten ed position, and means forming a connection between the locking means and said retracting means on the initial unlocking movement of said locking means in raising the drill, said retracting `means then moving the locking means on making said the bits.

ijmrill, a bit holder including a rack, a piniongaging the rack, and a rack bar including a rack extension in engagement with said pinion, said rack extension rotating the pinion and extendin the rbit holder upon movement of the rack ar by gravity.

8. In a drill, a bit holder including a rack, a pinion engaging the rack, a rack bar .including a rack extension in engagement with said pinion, said rack extension rotating the pinion and extendin the bit holder upon bar by l avity, and means engaging a portion of t e rack bar for limiting the movement of the rack bar.

drill, a. bit holder including a rack, a pinion engaging the rack, cluding a rack, in ent with said pinion, said rack extension rotating the pinion and extending the bit holder upon movementof the rack bar by gravity, means enbits a. rack bar init extending connection, to retract l nio gaging a portion of the rack bar for limiting the movement thereof, and means partly incasing the rack bar and supporting the limiting means.

10. In a drill, a carrier casing, side plates fixed in spaced relationship in 'said casing, bit carriers slidably supported on'said side plates, and gravity operated means movable lgetween the side plates for extending the its.

11. In a drill, a carrier casing, side plates fixed in spaced relationship in the carrierv casing, a transverse rib formed on each side' plate, a bit holder having a guide slot receiving the rib of one of the plates, a rack formed on the bit holder, a pinion engaging the rack, a pinion supporting shaft mounted in the side plates, a rack plate movable between the side plates -and having a slot, a rack extension carried by the rack plate engaging the pinion, and a guide pin lixed in the side plates and passing through said slot.

13. In a drill, oppositely extensionable bit holders having rack portions, a pinion meshing with each rack 'and oppositely rotatable on a common shaft, each pinion having a notch, a pair of rack plates each having a rack extension engaging one of the pinions,

and a latch movable relatively to the rack plates and arranged to enter said notches when in alinement, upon rotation of the pinions by the rack extensions under the action of gravity.

14. In a drill, oppositely extensible bit holders including racks, oppositely rotatable pinions engaging the racks each pinion having a slot, a common shaft for the pinions, rack plates including rack extensions engaging the pinions 'and rotating them in one direction ppon movement of the racl; plates by gravity, and a latch movable with the rack plates through a portion of theirl move ment and arranged for additional when the'rack plates come to rest, and enter thc then alined slots of the pinions.`

l5. In a drill, a bit holder having a raak, a pinion engaging a rack, said pinion having a notch, a rack plate for rotating the pinion a latch engaging the notch and locking the bit holder to the extended pesi means carried. by the raclr plate slot, and a dogy carried by by a portion of the latch upon withdrawal of the latch from said notch, to cause the rack plate to be carried therewith upon continued movement of the latch.

16. In a drill, a bit holder operating pinion having a notch, a rack plate for rotating the pinion to retract the bit holder upon the upward movement of the rack plate, a latch engaging the notch to lock the bit holder in the extended position, the latch being withdrawn from the notch on the initial movement in withdrawing the drill, and engageable means carried by the rack plate for abutting a portion of the latch to cause the rack plate to move upward on continued movement of the latch.

17. In a drill, a bit holder operating pinion having a notch, a rack plate for rotating the pinion to retract the bit holder upon the upward movement of the rack plate, a latch engaging the notch to lock the bit holder in the extended position, the latch being withdrawn from the notch on the initial movement in withdrawing the drill, engageable means carried by the rack plate for abutting a portion of the latch to cause the rack plate to move upward on continued movement of the latch and means for guiding and limiting the movement of the rack plate.

18.1In a drill, a vertically movable rack plate, a relativeiy movable latch having a the rack plate, including a nose occupying the slot and adapted to be engaged by the base of the slot to carry the rack plate with the latch.

upon continued movement of the latch in the vertical direction.

19. In adrill, a rack plate having a chamber, a dog pivoted in the chamber, having a nose projecting beyond an edge of the rack plate, and a latch movable relatively with respect to the rack plate, and having a dog slot receiving the nose.

20. In a drill, a rack plate having a chamber, a dog pivoted in the chamber, having a nose projecting beyond an edge of the rack piate, a latch movable relatively with respect to the rack plate, and having a dog slot receiving the nose, and guiding means holdin the latch in proper relationship to the rac plate.

"21. In a drill, a rack plate having a cenral passage, with a chamber opening into the passage and to one edge oi' the rack plate, dgg pivoted in the chamber including a inortise accessible from the opening of the chamber and. adapted to receive a lever, the dog having a nose projecting into the c Jntral passage, and latch movable in sage, having dog slot adapted to receive the nose.`

In a drill, a pair of racl.Y plates incind sep .e members spaced apart to leave assage, straps secured to the scparate members to form a composite rack plate body, adjacent portions of the-rack plates bein cut away to form a chamber at one side o said passage, a dog pivoted in said chamber with a nose projecting into said passage, and a latch occupying the central assage with a slot receiving the nose and aving eut-away portions receiving the straps.

23. In a drill, a carrier casing, side plates fixed in spaced relationship in said casing, rack plates sldable between the side plates and having slots, pins carried by the side plates occupying the slots to limit the movement of the rack plates, a latch slidable between portions of the rack plates and having a slot longer than the rack plate slots to permit additional relative movement of the latch with respect to the rack plates, and a pin mounted in the carrier casing and occupying said slot.

24. In a drill, a carrier casing including extensible bits, supporting means for the extensible bits, and means mutually carried by the carrier casing and said bit supporting means, for directing a stream of liquid against the bits.

25. In a drill, a carrier casing including extensible bits, means including carrier side plates, for supporting the extensible bits, and means carried by the carrier casing and said-bit supporting means forming orifices for directing a stream of liquid in opposite directions against the bits.l h

26. In a drill, the combination of a drill stein having an enlarged head provided with opposed slots, a carrier casing includin bit carriers adapted to be extended into loc ing engagement with said enlarged head by entrance into the slots, and lugs for supporting the carrier ce sing.

27. In a drill, a drill stem having an en-` larged head provided with opposed slots, bits adapted to be lowered into the stem, gravity operative means for extending the bits, alowering cable includin a member movable with respect to sai extending means, and a do arranged to prevent initial relative motionietween the movable member and the gravity operated means, but

adapted to be tripped to permit saldi relative motion of the gravity operative means to extend the bits into contact with said stem while lowering the bits, said bits extending into said opposed slots uppnvreaching the enlarged head. -l

28; In a drill, a drill stem, a carrier casing including extensible bits adapted to be lowered into the drill stem, and breakable supporting members for `supporting the carrier casing.

29. In a drill, a drill stern having a rece at the lower edge, an inwardly extending lug including a shank occupying and secured in the recess, the neck joining the lng and the 'lug under normal conditions.

30. In a drill, a carrier casing having 0pposed openings at the bottom, a side plate mounted in the carrier casing, said plate including an .enlarged head providing shoul-v ders occupying opposite corners of said openings, a rib orined transversely of the head, a bit carrier including a guide slot receiving the rib, and means for extending the bitcarrier on the rib through one of the openings.

3l. In a drill, a drill stem including an enlarged head having a slot, a carrier casing having an opening adapted to aline with said slot, a side plate fixed in the carrier casing and having an enlarged head providing shoulders occupying oppositecorners of said openings, a rib formed transversely of said head, a bit holder having a guide slot receiving the rib, and means or moving the bit holder upon the rib into the alined opening and-slot.

32. In a drill, a carrier casing, side plates fixed in said casing, slidable' rack plates mounted between the side plates, extensible bits, interposed means for extending the bits through movement of the rackplates, a latch for locking said means, a stem carried by the latch, and a gripping head mounted on the stem. l

33. In a drill, a carrier, extensible bits, means relatively movable by gravit with respect to the carrier for extending t e bits, a member relatively movable with respect to said gravity movable means and adaptedv .bits supported on the carrier, means operated by gravity to extend the bits and movable with respe'ct to said latch, and a dog pivoted on said means 'nominally engaging said means, said dog being. adapted to be tripped out of enga ement with the latch to permit a portion o' 'the gravity operation of said means and extend said bits into engagement with said drill stem.

` 35. Ina drill, the combination with the drill stem, of a latch adapted to receive the tongs of a lowering cable, bits adapted to be extended into engagement with said stem during the lowering of the drill, gravity operated bit extending means, and a dog -the latch to prevent the graviity opration of posed extended position,` `means for exten v means actin .as a'dri the drill,`an

said means normally engagin o hold the bits in the retracte position, saiddog being adapted to be tripped'to a disengaging position to permit the'bweight of said gravity OEerated means to 'e in active position for t e further extension'ofthe blts. 4

`36. In a drill, bits adapted to occupy the avit operated movable 1n .tlie bits, combined y support -in lowering -as looking means enga'ng the movable extending means when the 1 extended, said combined means'being initially movable in retracting from the lock ing engagement with said movable-,extending means in raising the drill, .aa'dhnetns arranged-to provide-a fixed co etween said combined means and said' gravity operated means, after Aa predetermined initial movement of said combined means, to actuate said gravity operated meansin the other direction on continued-'movement of said combined means, and retract thbits.

37. In a drill, a carrier casing having op.

openings, and" mounted irl-,said casing,eac h being formed withan enlargedhead to provide av pair of shoulders for restin in saidopenings, each head having 'a bevej ed portion directed inwardly. j

38; In a drill, a carriercasing having opposed openings, ,carrier side platesmounted `m saidcasing, each being formed with. an enlargedhead to ravida a'pair of shonlders 'for -restin in sai openings, each head hav-V ing a beve ed portion directed,i`nwardly, and a .closure plate mounted in said casing ad- 'ts are Y h .when the end of the cai-rief .side plates..

stemhaving an enlarged jacent to each enlarged head, said plates having beveled, portior adjoining the beveled portions of the heads to provide Huid orifices; p y

39. In a drill adapted to be lowered into a drill stein, extensible bits,a carrier casing including means for supporting the extensible bits, gravityoperated means including com osite rack plates, revoluble means inclu lng pinions adapted to be op said rack plates to extend the blts, a latch movable with respect to said plates and avillahead ada ted to receive the tongs of a owering cabe, said latch having a dogi slot, and a dog pivoted on one of the rac plates with a the dog slot, said dog including a beveled top portion adapted to lie against said latch beneath 'the dog slot when the carrier casing is su ported by thecable tongs in lowering the di'ill into the stem, ing then freely sus ended and pressing the bits into Contact wlth the walls of the drill stem in readiness to fully extend the bit drillstem is reached. drill, the combination of a drill head provided with opposed bit slots at the end, inwardly extepdin'g lugs at the end of the head, a carrier casingadapted to be lowered into place on the 1u in the enlarged head, bits carried b t e carrier casing and in contact with e inner wall of the stem in lowering,

'40'.Ina

'a'nd inverted V-shaped guides. between the opposed slots,I adapted to direct the contacting bits toward said slots.

oscAn MARTIN CARTER.

erated bv nose adapted to occupy said rack plates be-

Images