US1736518A - Automatic feed-control apparatus for well-drilling mechanisms - Google Patents

Description

Nov. 19, 1929. J. BRICKEN 1,736,518

AUTOMATIC FEED CONTROL APPARATUS FOR WELL DRILLING MECHANISMS Filed June 9, 1926 I 8 Sheets-Sheet l as T U. 116

53 I Q A as m I INVEN I'OR. L/OHN BRICKEN ATTORNEY.

Nov. 19, 1929. .1. BRICKEN AUTOMATIC FEED CONTROL APPARATUS FOR WELL DRILLING MECHANISMS Filed June 1926 8 Sheets-Shem;

Biz .2

| lvllll llllI I: ll IIIIIIII H INVENTOR. doHrv BR ICKEN A TTORNEY.

Nov. 19, 1929. J. BRICKEN 1,736,513

AUTOMATIC FEED CONTROL APPARATUS FOR WELL DRILLING MECHANISMS Filed June 9, 1926 8 Sheets-Sheet 3' 82 86 9! M I25 66 85 GT INVENTOR. (/OHN BRIG/(EN BY. 5% v ATTORNEY No'v. 19, 1929. J. BRI C EN 1,736,518

A UTOMATIC FEED CONTROL APPARATUS FOR WELL DRILLING MECHANISMS Filed June 1926 8 Sheets-Sheet 4 [XI "EN TOR. don/v BR: KEN

A TTORNE Y.

Nov. 19, 1929. J. BRICKEN 1,736,518

AUTOMATIC FEED CONTROL APPARATUS FOR WELL DRILLING MECHANISMS Filed June 9, 1926 a Sheets-Sheet 5 1 NVEN TOR. don/v BRICKEN ATTORNEY.

J. BRiCKEN 1,736,518

Nov. 19, 1929.

AUTOMATIC FEED CONTROL APPARATUS FOR WELL DRILLING MECHANISMS Filed June 9, 1926 8 Sheets-Sheet 6 INVENTOR dohw BRICKEN A TTORNE Y.

J. BRICKE N AUTOMATIC FEED CONTROL APPARATUS FOR WELL DRILLING MECHANISMS 8 Sheets-Sheet 7 Nov. 19, 1929.

Filed June 1926 6 no I 7 IO 95 O KG x s7 9 INVENTOR.

. (bu/v BRICKEN I V ATTORNEY.

Nov. 19, 1929. .1. BRICKEN 5,

AUTOMATIC FEED CONTROL APPARATUS FOR WELL DRILLING MECHANISMS Filed June 9, 1926 8 Sheets-rSheet 8 INVENTOR.

L/OHN BRICKEN ATTORNEY.

Patented Nov. 19, 1929 UNITED STATES PATENT oFrIcE JOHN BRICKEN, OF LOS ANGELES, CALIFORNIA, ASS-IGNOR OF ONE-HALF T0 REGAN FORGE & ENGINEERING- COMPANY, '01? SAN PEDRO, CALIFORNIA, A CORPORATION OF CALIFORNIA AUTOMATIC FEED-CONTROL APPARATUS FOR VVELL-DRILLING MECHANISMS Application filed June 9,

This apparatus relates to a mechanism for automatically controlling the feed of well drilling mechanism.

It is an important object to provide a feed control mechanism which will automatically adjust the drilling mechanism to suit the varying geological formations encountered during drilling operations.

Another object is to provide a mechanism that will efiiciently perform the functions of independent mechanisms now generally utilized in well drilling operations.

Anotherfobject of my invention is to provide apparatus that will maintain the equi librium of a predetermined load of a rotary drilling tool, during its operation.

Briefly, the important feature of the invention resides in an electric motor, having its rotor and the field operating in opposite di rections to each other for the purpose of maintaining a predetermined load of the rotary drilling tool and operating the same,

lhe rotor of the motor being used for driving the draw works (hoisting drum), while the field is used for operating the rotary table, both the rotor and field are connected to suitable sets of independent gears for transmit ting power alternately to draw works (hoist ing drum) and the rotary table as occasion demands. The ratio of the gearing of the field is adapted to rotate the rotary table at the required speed, and the ratio of the gearing-of the rotor is adapted to lift the entire length of the drill stand for predetermined depth of the well.

As an example, when the well is started the drill stand has a minimum weight and imposes a minimum torque on the drill, and at the end of the drilling the drill stand possessing the maximum Weight will impose a maximum torque on the drilling tool. In order to maintain equilibrium of a predetermined torque on the drilling tool a plurality of brakes are employed, their tension being controlled by means of adjustable springs.

The operation of the brakes is accomplished by the movement of the apparatus as a whole, the suspended motor controlling the brake action by its swinging movement, which is in turn entirely controlled by the variations of 1926. Serial No. 114,640.

the torque resulting. from the operation of the drilling bit, the greater the torque the greater the tendency for the motor to swing.

Adjustment of the apparatus as to operationis accomplished by means of a. spring whose tension may be varied to regulate the action of the brakes. This action allows the motor (which controls the brakes) to act in a negative direction in order when the torque for the drilling bit decreases below the normal (resulting from an absence of material to cut) the equilibrium of the motor is disturbed in the opposite direction to permit the draw works.to back up as the speed of the bit increases, this movement a-utomatical ly lowering the bit until obstructions are again encountered to restore the required equilibrium.

The above objects are accomplished by means of the apparatus described in the following specification reference being had to the accompanying drawings forming a part thereof, in which,

Fig. 1 is a sectional elevation of an oil derrick of usual form showing the relation of the feed control apparatus to the rotary well chilling mechanism.

Fi 2 is a front elevation of the apparatus.

Fig. 3 is a central vertical section thru the ap 'ia-ratus.

Fig. 4 is an elevation of one end of the apparatus.

Fig. 5 is an elevation of the oppositely disposed end.

Fig. 6 is a transverse section taken on line 6-6 of Fig. 3.

Fig. 7 is an enlarged detail elevation of the lower portion of one end of the apparatus, partly broken away and partly in section, illustrating the braking; mechanism.

Fig. 8 is a top plan View of the braking mechanism shown in Fig; 7

Fig. 9 is a. partial sectiontaken on line 99 of Fig. 3, showing the means of driving the.

same in a fixed position.

Referring now particularly to the drawings and particularly to Fig. 1 which illustrates the placement of the apparatus with relation to a rotary drilling rig of usual construction. In the view referred to, indicates the derrick platform, 11 the partially drilled well, 12 the well casing, 13 the vented casing head, 14 the drill stem carrying the usual fish tail bit 15, the stem being connected at its upper end to the Kelly 16, and its connected parts, such as the rotary swivel 17, casing hook 18, sheave 19, whose cables pass over the usual crown block 21, secured to the upper end of the derrick frame. As all the above described parts are of well known construction, and as they do not form a part of this invention no further detailed description is thought to be necessary.

The automatic feed control apparatus is located to one side of the derrick platform and in line with the rotary table which is rotated by, and is automatically controlled by the apparatus, as will be more particularly described further on.

The frame of the apparatus consists of two angular frames 26, 27, preferably formed of cast iron provided at their upper ends with bushedbearings 28, 29, and two roller bearings 30, 31, locatedin vertical alinement directly therebelow, the bearings being carried on transverse webs 32, 33, of the frames as clearly shown in Figs. 4 and 5 of the drawings.

The power actuating mechanism of the apparatus is here illustrated as consisting of an electric motor 35, composed of two rotary members 36, 37, either or both adapted to act as the rotor, and as the specific construction of the motor forms no part of my 'invention no extended description of the same is thought to be necessary, except to clescribe the operation of its rotary members as they affect the functions of the apparatus. Motor is connected to the apparatus in "the lower part thereof by means of a swinging frame 38 of yoked form, the upper ends of the vertically disposed arms 39, 40, of the frame forming bearings, 41, 42, bearing y 41 engaging a hollow hub 43, formed integral with the angular frame 2'? of the apparatus, while bearing 42 swingingly engages a hollow sleeve formed on the upper end of an auxiliary supporting frame Outer motor member 36 rotates in one dirco 'tion and drives the rotary table operating shaft 45, while the inner rotary motor memher or shaft 37 is held against rotation by the brake bands 46, 47. In order to rotate the rotary table drive shaft 45 the shaft of motor member 36 is provided with a pinion 48, which meshes with and drives a gear 49 keyed to a shaft 50 disposed in hearings on the end frame 27 of the apparatus, the inner end'of the shaft 50 carries a bevelled pinion 51, that in turn meshes with a similar pinion 52 keyed to the rotary table operating shaft 45, said shaft being provided with the usual disconnecting clutch 53 that may be operated to disconnectthe table drive shaft from the apparatus when it is desired to operate the draw works or hoisting drum independently of the table.

The inner rotary member 37 of the motor is normally held against rotation during the operation of the drilling mechanism by an automatically controlled brake mechanism 55, of the band type pivotally connected to the lower transversely extending member 57 of the yoked frame. Keyed to the outer end of shaft 58 of the inner rotary member of the motor is a pinion 59. that meshes with a gear wheel 60, keyed to the shaft 61 of the winding drum. Shaft 61 is mounted in a bearing 62 formed on frame 26 of the apparatus. Keyed to the hub of gear is a pinion 63 that meshes with an external gear 64 formed on the periphery of a driving clutch member 65. The hub of the clutch member is keyed to a shaft 66 disposed in bearings 67, 68, formed on the upper ends of frames 26, 27, and is provided with an inwardly extending annular flange 69, that 'forms a housing for a friction plate clutch mechanism of usual construction, in this instance saic. mechanism consists of a plate 70, loosely mounted on the hub71 of the housing, its outer face adjoining the hub 71 of member being recessed for the reception of a plurality of clutch operating coiled springs 72.

Loosely mounted on shaft 66 is a winding drum 75, for controlling the main cable 76 when operated to raise and lower the drill stem and its attached bit, as will be more fully described hereinafter. The end of drum adjacent the clutch member 65 is provided with an annular recess 80, and the inner circular wall 81 of the recess is transverselygrooved or slotted for receiving the teeth formed on the inner circular edge of a plurality of f iction plate rings 82, the inner peripheral surface of the flange 83 of the driving clutch member 65 is also provided with grooves or teeth similar in form to the grooves on wall 81 of the drum recess 80, that are engaged by teeth formed on the frietion plate rings 84, the rings 82 and 84 be ing disposed in interposed relation. From the foregoing it will be apparent that when the friction rings are out of clutching engagement that the rings secured to member 65 will rotate therewith, but when the plate 70 is moved inwardly towards the drum the coiled springs 72 will force the two sets of plates into iilctional engagement to operate the winding drum.

The clutch mechanism above described is normally in engagement and is only operative on a movement of the swinging yoked frame that carries the power actuating mechanism. Mounted in bearing 28 of end frame 26, is an externally threaded sleeve 85 adapted to be reciprocated thereon by an internally threaded sleeve 01' nut 86 through the me dium of a lever 87 which is keyed thereto (see Fig. 3), the lower end of said lever being pivotally secured to a lug 88 formed on the yoked frame. Sleeve 85 on its inner end is provided with an annular flange 89 that engages one member of a thrust ball hearing 90. Projecting from the outer face of clutch plate 70 through openings 91 of the driving clutch member 65, are pins or lugs 92 rigidly secured to a ring 93 hearing against the outer member of the thrust bearing 90. From the above it will be clear that when the yoked frame is caused to swing on its pivoted bearings by reason of an underload, the lever 87 will rotate the sleeve 86 to cause a reciprocation of the sleeve 85 outwardly, thus compressing the coiled springs 72 for disengaging the clutch rings 82 and 84 and thereby allowing the cable 76 to unwind and lower the drill stem until the drilling hit again engages the formation in the bottom of the well.

The braking mechanism 55 that holds the inner rotary member of the motor against movement during the rotation of the outer member of the motor, preferably consists of a pair of segmental brake shoes 95, 96, hingedly secured at their lower ends to member 57 of the yoked frame and are oppositely disposed, their inner faces being provided with the usual brake linings.

The upper ends of the segmental brake shoes abut against an S-shaped abutment member 98 that is pivotally secured to one of the vertical arms 39, 40, of the swinging yoked member, the adjustment means consisting of a downwardly extending arm 99, an adjusting lever 100 pivotally secured to the lower end of said arm, its free threaded end passing through a pivotally secured adjusting block 101, nuts 102 providing a means for holding the lever in an adjusted position. By means of the above described adjustment mechanism,

the brake shoes may be adjusted to compensate for the wear of the brake linings and to also maintain a predetermined load.

Pivotally attached to the lower transverse bar 57 of the yoked frame 38 is a rod 105, threaded for the reception of an adjusting nut 106. and. having a sleeve'107 rigidly secured thereto, said sleeve passing through an opening formed in an upstanding arm 108 secured to one of the auxiliary supporting frames 44 of the apparatus. Mounted on the sleeve 107, is a coiled spring 110, adapted to return the swinging yoked frame to its predetermined position (see 6) after the hoisting drum has ceased its operation.

Assuming that the drilling of an oil well 'hasstarted and that the drill stem and its attached drilling bit is within the hole. Power is delivered to the motor to drive the outer member 86, the inner member 37 being held against rotation by the brake mechanism 55. The rotation of the outer motor member drives the rotary table drive shaft through the medium of the gearing as heretofore explained. hen the drill bit encounters an unusual geological formation that tends to impede its rotation, the outer motor member will, in consequence, become overloaded, causing the gear pinion 48 to ride upwardly on. gear 49 and cause a swinging action of the yoked frame 57, the frame swinging outwardly in the direction of the arrow shown in Fig. 7. As the frame starts to swing the braking mechanism is released through the medium of the S-shaped abutment member 98 in order that the inner rotary member of the motor may rotate in the opposite direction to drive the hoisting drum and wind the main cable 76 to raise the drill stem, and thus release the overload. As the overload on the outer motor member 36 is released, the arm 105 through the medium of the coiled spring will force the yoked frame with the motor attached thereto back into its normal position to again allow a complete operation of the rotary table.

When the drilling bit 15 is operating on an underload the pinion 48 will not possess sufficient load to hold the yoked motor frame against the spring 110 in a normal working position; the spring will then force the yoked frame in a direction opposite to the direction indicated by the arrow in F ig; 7. This movement automatically operates the rod or lever 87 to release the friction clutch to permit the winding drum to rotate because of the load imposed by the weight of the drilling tools and unwind the cable 76 and thus lower the drill stem and bit to enable the cutting or drilling action of the same to be resumed. Should the drill 15 encounter an unusually hard formation which will naturally impart an extra heavy overload to the outer rotary member 36 of the motor, then the frame will again be swung in the direction of the arrow (see Fig. 7) until it is stopped by an emergency brake 111. This brake is best shown in Fig. 7 and consists of a segmental shoe 112 provided with a brake lining, and pivotally attached at its lower end to the yoked motor frame bar 57, its upper end being pivotally secured to the inner end of an actuating rod 113 passing through a bearing 114, and operating handle 115 providing a means for adjusting the same.

When it is desired to operate the winding drum shaft 66' independently of the drum, a hand brake mechanism 120 is provided consisting of a band 121 disposed on the flange" 69 of the drum.7 5, its ends being engaged by the threaded end of a brake operating rod 122-mounted in a bearing 123, the free end of the rod being provided with an operating handle 12d.

Secured to each end of the drum shaft 66 is a cat head pulley 125, and when the operator desires to use the cat heads the hand brake 120 is utilized to hold the winding drum stationary. The operating lever 126 is t ien pushed downwardly to turn the nut 127 to force the friction plate 70 to disconnect the clutch, thereby rendering the drum inoperative. The yoked frame is now swung in the direction of the arrow (Fig. 7) by means of a hand operating lever 130 against the abutment brake 111, which movement will securely hold the outer rotary member 36 of the motor against rotation. The movement of lever 130 will simultaneously release the brake mechanism 55, to permit the rotation of inner motor member 37 to drive shaft 66 to the ends of which the cat heads are secured. This shaft 66 may be rotated in either direction by merely reversing the electric motor.

lVhen unusual or excessive loads are to be raised by the main cable 76 it becomes necessary to operate both motor members without operating the rotary table drive shaft. This operation is accomplished by stoppin g the operation of the motor and disconnecting the clutch 53 on the rotary table drive shaft. Pinion 132 which is rotatably mounted on one end 188 of the bell crank lever 13% is then brought into mesh with gear 135, and pinion 156, power being again applied to the motor, and the lever 130 held in such position that the brake bands 55, 56, will be disengaged from the drum 103, thus causing the motor members to rotate in directions opposite to each other, and permitting the winding orum being operated in the desired direction.

The apparatus may be adjusted to obtain the necessary load on the drill bit 15, this being accomplished by rotating nut 106 in either direction to change the tension of spring 110, in order to change the swing of the yoked motor frame, it being understood that the swing of the frame controls the raising and lowering of the drill stem. The adjustable set screw 138 acts as a stop for the swinging yoked frame in adjusting its releasing movement. The releasing movement of the lever 87 may also be accomplishedby means of the handle 126, heretofore described. Operating lever 126 is formed integrally with the threat ed nut 12? that engages the screw threaded sleeve 28 rigidly secured to one of the side frames 26 of the apparatus. By moving the lever upwardly or downwardly the operator may quickly adjust the distance the swinging motor frame has to travel before the clutch disks will engage to operate the hoisting drum.

What I claimis:

1. Apparatus of the class described com-a prising driving and feeding means, a motor for actuating the same, said motor being arranged to move bodily in response to prede termined driving loads, and means controlled by the body movements of the motor for controlling the feeding and driving means.

2. An apparatus for controlling the operation of a rotary well drilling mechanism comprising a hoistingmechanism and rotating mechanism, a power apparatus comprising a motor having oppositely rotatable members for operating said mechanisms alternately, and a brake mechanism mechanically controlled by said power apparatus for retarding one of said mechanisms during the operation of the other.

An apparatus for controlling the rotation and feed of a rotary well drilling apparatus comprising an electrically operated motor including a pair of rotary members, one of said members connected to means for rotating the drilling mechanism and the other of said members connected to said drilling mechanism for raising and lowering the same, and automatically controlled mechanical brake means associated with one of said motor members for resisting the same during the operation of the other member.

4. An apparatus for automatically controlling the rotation and feed of a rotary well drilling mechanism comprising a swingingly mounted electric motor provided with two oppositely rotatable members, and mechanism connected to said members and controlled by the swinging movements said motor for maintaining a predetermined lead on the drilling mechanism during its operation.

5. An apparatus for automatically controlling the rotation and feed of a rotary well drilling mechanism comprising a'drill bit rotating and hoisting mechanism, a pivotully suspended motor for operating said mechanisms, and means operated by the sa n. movement of the motor to retard the movement of one of the mechanisms while the other is in operation, whereby to increase or decrease the load on the drilling bit during its operation.

6. An apparatus for automatically controlling the rotation and feed of a rotary well drilling mechanism including its drilling bit, a hoisting and lowering mechanism for the drilling mechanism, means for rotating the drilling mechanism, an electric motor for actuating said hoisting mechanism and means for rotating the same, and a brake mechanism operated by the motor to operate one of said mechanisms and to hold the other against movement. I

7. An apparatus for automatically controlling the rotation'and feed of a rotary well drilling mechanism comprising a frame, a hoisting drum mounted on said frame and connected to the drilling mechanism for raising and lowering the drilling mechanism to maintain a normal load on the drilling bit during its cutting operation, means to rotate said drilling mechanism, an electric motor ineluding a pair of rotary members for actuating the hoisting drum and the drilling mechanism rotating means, a braking mechanism for retarding one of said motor members while the other is operating, a clutch mechanism connected to the hoisting drum, and means connected to one of the motor members and to the hoisting drum for operating the clutching mechanism.

8. An apparatus for controlling the rotation and feed of a rotary well drilling mechanism including a drill bit, comprising hoisting and rotation means, an electric motor including two rotary members mounted for swinging movement, the members of said motor being connected in driving relation with the hoisting and rotation means, and means to adjust the swinging movement of the motor, whereby to control the raising or lowering of the drill bit.

9. An apparatus for automatically controlling the rotation and feed of a rotary well drilling mechanism comprising a swingingly mounted electric motor including two oppositely rotatable members for rotating the drilling mechanism and operating the hoisting means, means actuatable by the swing-- ing movements of said motor for controlling said drilling mechanism and hoisting means and means for utilizing both of the motor rotary members as a speed reducing unit r V 10. Apparatus of the class described comprising drilling mechanism, a stationary frame and a pivotally supported motor carried by said frame and adapted to swing on the pivot in response to the motor load for controllingthe operation of said mechanism.

11. Apparatus of the class described coniprising a drill, means for hoistingand feet ing said drill, a motor having a rotor and a rotatable field, one of which is adapted to drive said drill and the other of which arranged to drive said means for hoisting, or feeding said drill, and mechanism controlled by said motor for regulating said last named means to maintain a predetermined load on said motor.

12. Apparatusof the class described comprising a motor having a rotor member and a rotatable field member, drill driving means operable by one of said members, feeding means operable by said other motor member, means normally holding said latter member against rotation, and automatic means for releasing said member upon overload whereby said drill feeding means isoperated to reduce the overload to predetermined limits.

13. Drill driving and feeding mechanism comprising a pivotally mounted motor having a rotor member and a rotatable field member, one of said members beingv adapted to drive the drill and the other being arranged for operating said feeding mechanism, a brake normally holding said last named member against rotation, said other motor member being arranged to effect a pivotal movement of saidmotor upon predetermined overload, and means actuatable upon the said pivotal movement of the motor for releasing said brake'to permit actuation of said feeding mechanism to reduce the overload.

14. Apparatus of the class described com prising a drill driving mechanism, drill feeding mechanism, a motor having a rotor member and a rotatable field member, one of said members being adapted to operate said drill driving mechanism and the other IDOEOI member being arranged to operate said feeding mechanism, and means for automatically controlling the operation of said motor members to regulate the load on said drill.

15. Apparatus of the class described comprising a drill driving mechanism, drill feeding mechanism, a motor having a rotor member and a rotatable field member, one of said members being adapted to operate said drill driving mechanism and the other motor memher being arranged to operate said feeding mechanism, and means for automatically controlling the operation of said motor members to regulate the load on said drill, said means. comprising brake bands and'brake setting and releasing members.

16. Apparatus of the class described comprising a pivotally supported motor, drill feeding and driving means actuatable thereby, said driving means being adapted to eff ct a swinging movement of said motor upon overload, and means actuated upon the said swinging movement of said motor for controlling the actuation of said feeding means.

17 Apparatus of the class described comprising a pivotally supported motor, drill feeding means and drill driving means actuatable thereby, said motor being arranged to swing on its pivot in one direction past normal position upon overload and in the opposite direction past normal position upon underload on the drill, and means actuatable upon said swinging movements of the motor for controlling the feeding means and preserving uniform load upon the drill.

18. Apparatus of the class described comprising a frame, a motor sWingi-ngly supported thereby, drill driving means operable by said motor within predetermined load limits, a drill feeding means associated therewith, said motor being arranged to swing in onedirection or the other past normal position upon the overloading orunderloading of the drill, and means actuated bysaidmotor. in one of said movements: for. causing said feeding meansto feed the drill to the work, said motor being adapted upon the opposite swing ing movement thereof to actuate said feeding means is a direction to reduce the overload on the drill.

19. Apparatus of the class described comprising a motor having a rotor and a rotatable field, drill driving means actuatable by said field, and feeding means actua-table by said rotor, a brake for holding said rotor sta tionary during normal drilling operations, and means for automatically releasing said brake upon overloading of the drill to permit said rotor to actuate said feeding means in a direction to reduce the overload.

20. Apparatus of the class described comprising a motor having a rotor and a rotatable field, a clutch, drill feeding means actuatable by said rotor through said clutch upon the overloading of said drill, means for hold- 7 ing said rotor stationary during normal drilling operations, and automatically operated means for releasing said clutch upon the underloading of said drill for permitting the latter to feed toward the work.

21. Apparatus of the class described comprising a pivotally mounted motor, drill driving means actuatable thereby, drill feeding means comprising a drum, releasable means for holding said drum against rotation in a direction to feed the drill to the work during normal drill load, means for swinging said motor upon its pivot upon the underloading of the drill, and means actuatable upon the said swinging of said motor for releasing said holding means to permit the drill to gravitate toward the work.

22. Apparatus of the class described comprising a pivotally mounted motor, drill driving means actuat-able thereby, drill feeding means comprising a drum, releasable means for holding said drum against rotation in a direct-ion to feed the drill to the work during normal drill load, means for swinging said motor upon its pivot upon the underloading of the drill, and means actuatable upon the said swinging of said motor for releasing said holding means to permit the drill to gravitate toward the work, said holding means comprising a clutch.

23. Apparatus of the class described comprising a pivotally mounted motor, drill driving means actuatable thereby, drill feeding means comprising a drum, releasable means for holding said drum against rotat-ion in a direction to feed the drill to the work during normal drill load, means for swinging said motor upon its pivot upon the underloading of the drill, and means actuatable upon the said swinging of said motor for releasing said holding means to permit the drill to gravitate toward the work, said means for swinging said motor upon its pivot comprising a spring.

24. Apparatus of the class described comprising a pivotally mounted motor, drill driving means actuatable thereby, drill feeding toward the work, said holding means com-.

prising a clutch, said means for swinging said motor upon its pivot comprising a spring mechanism and adjusting means therefor for controlling the swinging movement of the motor.

Apparatus of the class described com prising a swingingly supported frame, a mo-' tor carried thereby, said motor having a rotor and a rotatable field member, drill feeding means comprising a drum adapted to be actuated by said rotor, a clutch normally effecting a driving connection between said rotor and drum, means for holding said rotor stationary during normal drilling operations, drill driving means actuatable by said rotary field member, said member being adapted to swing said frame from normal position upon the overloading of the drill, means for automatically releasing said rotor upon such swinging movement whereby said rotor can drive said drum in a direction to raise the drill to reduce the overload, means for swinging said frame past normal position in the opposite direction upon the underloading of said drill, and means for automatically releasing said clutch upon such movement of the frame to permit the drill to gravitate toward the work.

26. Apparatus of the class described comprising a swingingly supported frame, a mo tor carried thereby, said motor having a rotor and a rotatable field member, drill feeding means comprising a drum adapted to be actuated by said rotor, a clutch normally effecting a driving connection between said rotor and drum, means for holding said rotor stationary during normal drilling operations, drill driving means aotuatable by said rotary field member, said member being adapted to.

swing said frame from normal position upon the overloading of the drill, means for automatically releasing said rotor upon such swinging movement whereby said rotor can drive said drum in a direction to raise the drill to reduce the overload, means for swinging said frame past normal position in the opposite direction upon the underloading of said drill, and means for automatically releasing said clutch upon such movement of the frame to permit the drill to gravitate toward the work, said means for swinging said frame upon the underloading of the drill comprising a spring.

2?. Apparatus of the class described comprising a swingingly supported frame, a motor carried thereby, said motor having a rotor and a rotatable field member, drill feeding means comprising a drum adapted to be actuated by said rotor, a clutch normally effecting a driving connection between said rotor and drum, means for holding said rotor stationary during normal drilling operations, drill driving means actuatable by said rotary field member, said member being adapted to swing said frame from normal position upon the overloading of the drill, means for automatically releasing said rotor upon such swinging movement whereby said rotor can drive said drum in a direction to raise the drill to reduce the overload, means for swinging said frame past normal position in the opposite direction upon the under-loading of said drill, and means for automatically releasing said clutch upon such movement of the frame to permit the drill to gravitate toward the work, said means for swinging said frame upon the underloading ofthe drill comprising a spring, said spring being proided with adjustable tensioning means for controlling the swinging movement of said frame.

28. In combination a supporting frame, a shaft journaled therein, awinding drum on said shaft for raising and lowering a drill,

I an auxiliary frame pivotally suspended from said first frame, a motor carried by said auxiliary frame, said motor having a rotor and a rotatable field member, a drive pinion actuatable by said field member, a gear actuated by said pinion for driving a drill, a brake for holding said rotor against rotation during the normal drilling operations, the arrangement being such that said first mentioned pinion will travel on the periphery of said gear upon the overloading of the drill whereby said auxiliary frame will be swung from normal position, and means for automatically releasing said rotor brake upon such swinging movement whereby said rotor will drive said drum to lift the drill and re duce the overload.

29. In combination a supporting frame, a shaft journaled therein, a winding drum on said shaft for raising and lowering a drill, a clutch mechanism adapted to lock said drum against rotation relatively to said shaft, an auxiliary frame pivotally suspended from said first frame, a motor carried by said auxiliary frame, said motor having a rotor and a rotatable field member, a drive pinion actuatable by said field member, a gear actuated by said pinion for driving a drill, a drive pinion on the shaft of said rotor for driving said drum through said clutch, a brake for holding said rotor against rotation during the normal drilling operations, the arrangement being such that said first mentioned pinion will travel on the periphery of said gear upon the overloading of the drill whereby said auxiliary frame will be swung from normal position, means for automatically releasing said rotor brake upon such swinging movement whereby said rotor will drive said drum to lift the drill and reduce the overload, means for moving said frame in the opposite direction upon the underloading of the drill, and means automatically operable upon such latter movement of the frame for releasing said clutch whereby said drum is free to rotate on said shaft to permit the drill to gravitate to the work.

30. Apparatus of the class described comprising a frame, an auxiliary frame pivotally supported thereby, a motor carried by said auxiliary frame, a pinion driven by said m0- tor, a gear co-axially mounted with reference to the pivot of said auxiliary frame, said gear meshing with said pinion, drill operating means actuatable by said gear, the arrangement being such that said'pinion will move along the periphery of said gear upon a predetermined overloading of the drill operating means whereby said auxiliary frame will be moved upon its pivot from normal position, and drill elevating means adapted to bev actuated by said motor upon such swinging movement of said frame. 7

In witness that I claim the foregoing I have hereunto subscribed my name this 26th day of May, 1926.

JOHN BRICKEN.

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