US2907550A - Feeding device for rotary well drill - Google Patents

Description

Oct. 6, 1959 s. HEINISH 2,907,550

FEEDING DEVICE FOR ROTARY WELL DRILL Original Filed May 29, 1953 4 Sheets-Sheet 1 INVENTOR. G5 OEGE HE/N/SH a/04km Oct. 6, 1959 G. HElNlSH 2,907,550

FEEDING DEVICE FOR ROTARY WELL DRILL Original Filed May 29, 1953- 4 Sheets-Sheet 2 INVENTOR. 650m: Ha m/5H x41- rcinws ys Oct. 6, 1959 G. HEINISH 2,907,550

FEEDING DEVICE FOR ROTARY WELL DRILL Original Filed May 29, 1953 4 Sheets-Sheet 3 IN VE N TOR. Gaoeee f/E/N/SH BY 01AM 2) Arroe vE Y6 Oct. 6, 1959 e. HEINISH 2,907,550

FEEDING DEVICE FOR ROTARY WELL DRILL Original Filed May 29, 1953 4 Sheets-Sheet 4 1/ JNVENTOR. Geo/ase- //'/N/5H United States atent FEEDING DEVICE F OR ROTARY WELL DRILL George Heinish, Akron, Ohio Continuation of abandoned application Serial No. 358,400, May 29, 1953. This application February 5, 1957, Serial No. 638,418

2 Claims. (Cl. 255-22) This invention concerns rotary type well drilling machines and, more specifically, a new and improved methd of applying pressure to the drilling bit and regulating the feeding thereof as drilling progresses.

In this type of well drill, penetration of the formation is effected by means of a drill bit attached to the end of hollow drill rods or drill pipe and operated with a rotary motion. The string of drilling tools are suspended from a rotary swivel through which water is circulated to the bit at the end of the hollow rods for flushing the cuttings from the well being drilled. In order to impart power to the drill bit, the first drill rod below the swivel is generally an extra heavy hollow bar 'known as a Kelly 01 grief stem. This kelly is provided with the power transmitting means for obtaining the rotary motion of the tools from the well drilling machine. Usually this power transmitting means includes some form of bevel gear drive with a hollow spindle through which the kelly is both fed vertically and rotary driven.

It is frequently necessaryto apply pressure to the drill bit to elfect rapid penetration, particularly when hard formations are encountered at or near the ground surtace. vAlso, to obtain maximum cutting efiiciency and wear life of the drill bits or to obtain satisfactory cutting action when running core barrels for recovering cores of the formations being drilled, it is necessary to provide a rneans of feeding the drill rods under pressure. The rates of .feed and amount of pressure applied will vary widely with the variations in the formations being drilled. A number of ways of applying power for efiecting the pres- .sure and feed of thedrill bit have been and are at present employed on rotary type drills. The hydraulic method .is a commonly used method. This hydraulic method .usually employs hydraulic oil cylinders to pull down on .the Kelly or grief stem through a crosshead which is made .to grip the outside diameter of the kelly by set or clamp screws. A hydraulic pump system with reservoir and relief and control valves is used to control the rate of feed .and pressure developed by the cylinders.

.There are several construction and operating faults in- Eherent in the hydraulic pull down or feed mechanism. .Some of these are the following:

One, the cylinders are short in length, for cost-and opterating reasons, compared to the drill rod lengths. 2 /2 .110 3 foot stroke of cylinders to 15 to 25 ft. drill rod lengths.) This necessitates, when drilling, discon- .necting the pressure and feed a number of times during the use of a single drill rod because of the plurality of strokes of the hydraulic cylinder required to .force the drill rod its length. To some extent the lost .time is minimized by the use of an automatic chuck :head in place of the crosshead with clamp screws but .such a chuck head is quite intricate and expensive.

Two, every time the cylinders are to be disconnected from the kelly for a new stroke there is lost time to allow a'the bit to drill 01f to relieve the pressure and again time is required to build up the pressure and regulate the feed Patented Oct. 6, 1959 "ice considerably with diil-eren'tformations and kinds of drilling, the pump to operate the hydraulic cylinders should be a variable volume and pressure type. Such pumps are available, however, they are also quite intricate in construction and expensive. Therefore, the common practice is to use a single fixed capacity pump of a size largeenough to deliver the maximum pressure and volume needed; then a system of bypass and control valves is used to cut the maximum delivery to whatever is needed at the cylinders. This method of control wastes power and necessitates large oil reservoir and heat radiation means in the hydraulic system to dissipate the unused horsepower.

Pour, the hydraulic fluid is, for all practicable purposes, incompressible and there, therefore, is little flexibility and no Shock absorbing qualities inherent in its use as a feed operating means. The feed control is therefore quite sensitive to variations generated at the drilling bit and requires constant care on the part of the driller to avoid trouble and obtain maximum efliciency.

Other types of feed mechanisms include mechanical and electrical means which generally employ friction slippage or magnetic clutches in the power drives of the mechanisms. The principal advantage of these types is the fact that a full length feed stroke can readily be obtained and thus overcome the objection of the short stroke of the hydraulic system. Control of the pressure and rate of feed are, however, even more difficult than with the hydraulic system. As accurate control is most essential, this accounts for the popularity of the hydraulic method in spite of its high initial and operating costs.

The general object of the present invention is to provide a novel type of rotary drill feeding mechanism which overcomes the foregoing and other objections to and disadvantages of present types of apparatus of that character, and to provide rotary drill feed mechanism characterized by the use of air pressure in the power and control means for the drill.

One of the objects of this invention is to provide a simple method of obtaining a feed stroke for the full length of the kelly so that the feed of the drill need not be stopped except when adding a new length of drill rod.

Another object of the invention is to provide simple means of regulating the pressure and rate of feed automatically at all times and under varying conditions so as to prevent damage to the drilling tools or costly fishing jobs.

Another object of the invention is to employ a method of power application to the feed mechanism which will only use the power selected and needed at a given time while also providing for ready application of maximum power if desired and thus eliminate wasted power.

Another object of the invention is to provide a simple means for instantaneously cutting olf the power from the feed and disconnecting the feed for the immediate retraction of the kelly for the purpose of adding another length of drill rod.

Another object of the invention is to provide a flexible power transmitting medium with shock absorbing ability to permit easy feed regulation and to protect the drilling tools and machine. A still further object of the invention is to provide an audible signal in addition to visual means to indicate the specific feed taking place so that the operation of the drill will be easier for the driller and he will not be required to stay right at the controls all of the time.

To achieve these and other objectives I have selected the medium of compressed air for the operation of my I 3 feed mechanism for rotary drills and describe it in detail hereinafter.

n. or e o, nde stand; p es nven ion. pletely, reference should be had: to the accompanying aw s, hich dis lo ne embq ime t he P a es. of he n ntisnz. and. e e n Fig. 1 is a schematic View showing diagrammatically e.- con eq ie of h p e m c. q tr ea s 0 the ven iont h r eedi mea s 9 th ve n;

Fig. 2; is an enlarged front elevation, partially broken away dp al y hown. n r ica e t qn'ie the actual drilling. apparatus used in practice of the, invention;

i s a ment y e iq ak 91 .5 3 *3 of Fig. 2 of the pull down loop means;

Fig. 4 is an enlarged vertical: section of the distributor lve assem y d n he na r ms;

F s- 5 nd. r id nd. qi t e sva n e pectively, of a special operative lever means used. inthe d stri u or a ni m JF F g 8 9 r ef o t nd ba ens plan e esp c y. o pe ial. qq trq er he d r uto valve;

F gv s a men a y se in dica i hnw he r power cylinders are used as shock; absorbersin the apparatus; and

Fig. 11 is a horizontal sectionon line 1 111 of'Eig 4.

The invention relates to power feeding of rotary drills nd. inc ude a haf ap d, te e oup edz ee m a for a rotary drill, compressed air operated power cylinders or the like including power outlet means, means connecting an air supply to the power cylinders for operaion th reof, an me cqnne t ng h POW I. o e means to the shaft to rotate the shaft by at least substantially continuous torque forces.

In Fig. 1, the reference numeral 1 refers to an air compressor. This compressor may be any one of the several commercial compressors available and, for average work those that arein common use for the purpose of operating air brakes on highway equipment and the like, are entirely suitable. The compressor can be readily driven from the power. unit. of the drilling machine and, is used to, maintain a supply of air under pressure in a number of reservoirs 2. In a convent ionalmanner, the reservoirs may be interconnected. as. indicated and provided with controls to maintain. the air in the reservoirs between desired, pressure limits (for example 85; to 100 psi). The controls for. this purpose are indicated as a governor 3, an unloader valve 30, a pop or safety valve 5, and a pressure gauge 6. Obviously, with the compressor soequipped, only a slight fractional horsepower. will. be expended to drive the compressor except, of course, when the pressure in the reservoir falls below the governor controlled minimum, at which time theqornpressor will operateat its. full capacity andpo'wer.

The air reservoirs 2 provide the energy storage capacity for peak power demands of the feed1..mechanism while at the. same time providing for two essential operating needs viz., one, to permit the use of a variable amount of air (or power) for variable feed loads below the maximum and, two, to automatically cut off the power mput when no air is needed for operating the feed mechanism.

Referring to Figs. 1 and 2, reference indicated in general a conventional Kelly drivemechanism. through.

which a kelly 8 is fed vertically while at the samev time it is being rotated by suitable. drive. means from .the drilling machine. Supported on the structure of the drlll ng. machine or on the Kelly drivemechanism housmg is a feed drive shaft 9, which I propose to give a rotary-motion using the compressed air from reservoirs 2, and to feed the drill under pressure by such drive shaft 9 rotation.- To accomplish this, I support the shaft 9- on two frame bearings 10 and 11. Adjacent bearings Hand 11 and spaced equidistant transversely from Kelly 8 are two roller chain sprockets 12 and 13 with the Who e a rrangement being such that the sprockets 12 and 13 are keyed to the shaft 9 and so must turn with it, and the pitch diameters of the sprockets are transversely in alignment with the center of the kelly 8 so that the shaft 9 is offset from the center of the kelly and the tension strands of pull down chains 14 and 15 engaging the sprockets 12, and 13 are in alignment with the kelly, and, finally the sprocket hubs may be used to position the shaft 9 against endwise playor movement.

On the extended end of shaft 9 is mounted a ratchet hub and clutch drive drum 16 to rotate freely on the shaft on its bearings 17 and 18. As desired, the ratchet hub and clutch drive drum lo'may be connected to shaft 9 so as to rotate with itby means of a clutch 19. The clutch H is preferably of the friction type to permit instantaneous connection and disconnection of the feed shaft by conventional means. Surrounding the ratchet portion of the hub 16 are two axially aligned pawl carriers 20 and 21 and each of these carriers are provided with a plurality of pawls 22 by means of which the hub 16 andconsequently the shaft 9, when clutch 19 is engaged, can be forced to rotate. Each of the two. pawl carriers 20 and 21 is also provided with a lug or lever eye 23 so that they may be connected, through suitable linkage as indicated in Fig. 1, to two air cylinder piston rods 24 and 25 and thereby be given. angularoscillating movement directly proportional to the piston stroke length. 7

Pistons 24a and 25a are connected to. the piston rods 24 and 25, respectively. Two. air power cylinders or acting type i.e. air, and therefore power is applied only to one head of the pistons. Retulnstrokes of the pistons and the pawl carriers to which they are connected. is obtained by return springs 2.8. received in the cylinders and engaging the pistons. The two air cylinders or chambers 26 and 27 are rigidly attached or otherwise suitably mounted onthe drill frame or Kelly drive housing 7 to take the thrust reaction of the air pistons.

In the operation of the feed mechanism, air, controlled as to volume and pressure, is admitted and exhausted alternately to and from the power ends of the cylinders 26 and 27, One cylinder is exhaustingwhile the other cylinder is applying force, through its piston and its connecting linkage and pawlcarrier, toimpart torque to theratchet hub 16 and shaftv 9. The alternate distribution of the air tov the two cylinderstherefore imparts a con-- tinuous rotary motion to shaft 9. which through sprockets 12 and 13 pulls on: the two chains, 14 and 15. Means to utilize this motion and pulling force for application as a feed and pressure on the drill bit will be later de scribed together with some reference as to the advantages obtained indrilling,

Againreferring to Fig, l,tocontrol the air to the two power cylinders 26 and. 27, a distributing valve 29is used. This valve is intereonnected by suitable linkage to the piston rods 24 and 25 so that the valve is operated by their movement. This distributing valve requires certain characteristies essential to the proper timing and control of the air cylinders so that itsprinciples of construction are an essential part of this invention. The distributing valve 29, receives its supply of air from, the air reservoirs 2 through a control valve 30 which is used to regulate the air volume and pressure delivered to the distributing valve 29. The driller can, by changing the adjustment of valve 30, vary the rate and power applied to the feed as he may desire. Several regulating valves now in commercial use are entirely suitable for use as the valve 30- however, to the best of my knowledge, no suitable commercial product is available to perform the functions of the valve 29 in exactly the manner desired. While I have shown and will later describe in detail the distributing valve 29 to bemechanically operated fromthe power cylinder piston rods, I realize that the control connections between the power cylinders and the valve 29 can be made in a number of other ways, for example electric solenoids could be used, or hydraulic means or again additional air controls. The means of interconnection is a matter of construction, the essential elements being the operating characteristics of the valve 29 itself. It may be well to state at this point that the audible signal previously mentioned is also obtained as a part of the functions of the valve 29.

Preferably the control valve 30 is mounted convenient to the drillers other machine controls. Also desirable is an indicator gauge 31 to indicate the amount of pressure being applied to the drilling bit. This gauge is simply a conventional air pressure gauge but with its dial modified and calibrated to read in terms of pressure on the bit corresponding to various air pressures imposed on the gauge. These, together with a control for the clutch 19 are all of the controls necessary to operate my feed mechanism.

Referring to Fig. 2, the reference number 32 refers to a rotary swivel to which the kelly 8 is connected by an adapter or hub 33. As stated previously, thekelly 8 and drill rods are hollow to permit circulating water to flow through the drill bit 34. An inlet 35 for the water is indicated on the swivel assembly, it being customary to connect this inlet elbow to the water pump discharge outlet by means of a flexible hose. Hoisting tackle block 36, attached to the swivel 32 either by the customary hook and bail or by equalizing links 36a as shown, is connected to a hoisting drum of the drilling machine by cable strands 37 which operate over sheaves at the mast head. (Not shown.)

The body or stationary portion of the swivel 32 is provided with two guide arms extending transversely therefrom. The outer ends of these arms are guided along two vertical guides 38 and 39. Also provided on the swivel guide arms are two chain and cable attaching members 40 and. 41 which are spaced from butin alignment with the sprockets 12 and 13. From these attaching members 40 and 41 on the swivel assembly, the two lengths of roller chain 14-15 extend downwardly to sprockets 12 and 13 around which they pass a sufficient distance to permit full length travel of the swivel 32 along the guides '38 and 39. The lower ends of the roller chains 14 and 15 are connected by steel or other cables 42 to the top of connections 40 and 41. after passing around sheaves 43 and 44. Sheaves 43 and 44 are rigidly attached to the upper ends of the vertical guide members 38 and 39 which are in turn suitably supported on the drilling machine frame or mast structure in alignment with the Kelly drive and well to be drilled. At the connection members 40 and 41 and at. the connecion between the cables and chains, suitable adjustment may be provided to maintain the proper tension in the two loops so that the roller chains will remain in proper driving relationship with the sprockets on the power fee shaft.

From Figs. 1 and 2 and the description I have given, I believe it is fully apparent that the air power stored in reservoirs 2 may be readily used to apply a pressure feed to the drill bit 34 and, by the use of suitable control means of the air supply, that both the rate of feed and the pressure on the bit can be varied exactly as desired. Also it will be seen that, after the kelly has been fed downward its full length, the kelly can be retracted simply by disconnecting the ratchet mechanism from the feed shaft by disengaging friction clutch 19 and then these loose pieces may wedge or get under the drill bit causing an upward thrust and shock loads to develop in the string of drilling tools. When these shock loads and up thrusting forces reach the kelly at the top they must be absorbed and dissipated else destructive reactions will occurs. In conventional drills, some attempts to alleviate this condition are made by building steel compression springs or shear pins into the feed mechanism drives. As seenjin Fig. 10, these forces, in my feed mechanism, are transmitted back through the pull down chains, ratchet means and connecting linkage to finally be absorbed on the air cushion between the piston head and cylinder.

As previously stated, the control and distribution of the air to the power cylinders necessitates the use of an air distribution valve having certain characteristics essential to the proper timing and control of the action of the cylinders to assure a steady pressure and responsive feed on the drill bit. Since the feed shaft, in operation, always has a torque Whether the shaft is rotating fast or slow, the shaft must, at all times, be under power control of one or the other of the cylinders, else the tension in the pull down chains will not be maintained and the feed would be erratic. Again it would not do to admit air to one cylinder while the other cylinder was not being exhausted for that would cause both cylinders to apply power and double up the feed pressure. What is needed is a timing instant in which the work is transferred from one cylinder to the other so that the admission of air to one cylinder is concurrent with the exhausting of air from the other cylinder. This means an almost instantaneously operating or snap action control valve. Furthermore, the exhausting of the air from one cylinder must be controlled in such manner that the pressure in that cylinder is reduced proportionately to the pressure built up in the other cylinder so as to maintain a uniform torque in the feed shaft. Finally, the action of the valve to distribute air to the cyiluders must be timed to the piston action in the cylinders to assure proper action of the ratchet mechanism. All of these requirements I have worked out in the design and construction of a distribution valve 29 described in detail hereinafter.

Referring to Fig. 4 which is a composite cross-section to illustrate the various elements, the housing of the distribution valve 29 comprises a base 45 and a cover 46.

Mounted on base 45 are two air control valve assemblies 47 and 48 each of which comprises a tubular member with a partition or baffle 101 intermediate the ends thereof. Each so formed section of the tubular members 100 has a series of ports 102 or 103 provided therein and a valve sleeve 104 is slidably engaged with the periphery of the tubular member for either connecting the series of ports 102 and 103 for fiow of air therebetwcen, or for exposing the series of ports 103 to the interior of the cover 46 for air to be exhausted from the power cylinders, as described hereinafter. The inner tubular members 100 are held in position with a retainer or manifold 49 by means of a hollow stud 50 and a retaining nut 51. The ends of the tubular inner members 100 of air valves 47 and 48 are fitted int- o counterbores 105 and 106 in base 45 and retainer 49, respectively, and sealing gaskets are provided at these points. Air pressure tight connections for the air passages are maintained by drawing up nut 51 tightly.

As indicated in Figs. 1 and 4, air is supplied to the distribution valve 29 through the central hollow stud 50, it passes through the stud into the retainer 49 and through passages 107 and 108 provided it can enter air valves 47 and 48, respectively. The air from the supply reservoirs 2 is being fed through valve 47 at the left to power cylinder 27 while, at the same time, the air from cylinder 26 is being exhausted through valve 48 at the right into housing cover 46 and from it to the atmosphere through a suitable metering valve as described hereinafter. The inner tubular members 100 of valves 47 and 48 are bers 104a and suitablepackings for providing air-tight connectionwith the tubular members 100. Grooves 109 are formed in the outside circumference of the sleeves 104 for engagement with the valve sleeve shifter means, as later described. I

As can be seen in the valve assembly 47, when 'the sleeve 104- thereon is shifted on the tubular inner mem; her 100 so that both sets of air ports m2 and 103, are within the inner chamber 104a, then t he; air can pass through the air ports on one side of the bafile into the chamber and thence back through the air ports, on the other side of the baffle i.e. the air passes through the valve. However, when the valve sleeve 104 is shifted as seen in the valve assembly 48, so that the chamber 1040; in the sleeve therein covers only one set of air ports, then the supply air is shut off and simultaneously the other set of air ports 103 being uncovered permits 7 exhausting the air from the cylinder connected to that valve. Thus it can be seen that the alternate shifting of the air valves into the two positions described will alternately admit and exhaust air from each of the two cylinders. It is only necessary to shift the valve positions at the proper time. a

To shift the valve sleeves 104 of the air valves 47 and 48 both instantly and simultaneously, I have devised a snap action mechanism that operates from the power 7 cylinders 26 and 27. Base 45 of the distributor valve is provided with pivots 52 at which two valve shifter levers, an outer lever 53 and an inner lever 56, are at tached for oscillating movement. The outer lever 53 is actuated by the power cylinders through push rods 54 and 55. Lever 53 in turn actuates the inner lever 56 in a manner to be described but primarily powered by energy stored in a spring 57, the positioning of which is described hereinafter. It can be readily understood that the shifting of the air valves must occur at the end of the power stroke of the pistons 24a and 25a and therefore must be timed to the power cylinder operation, however, it also can be understood that the movement ofthe power cylinder pistons will at most times be relatively slow, 7

especially when drilling in hard rock and if this slow movement of the pistons is directly connected to shift the air valves 47 and 48, it would result in a slow shifting of the valves during the entire stroke in place of the desired shifting onlyat the end of the stroke.

The inner airvalve shifter lever 56 is a fork-shaped double end bell crank, the construction of which is more readily apparent from Fig. 5. It has the forked opening 110 to straddle the valve mechanism 47-48-49 and has double ends or levers 111 and 112 for connecting each to one of the air valves 47 and 48 through trunnion dogs 58, Fig. 11, which engage with and operate inthe circumferential grooves 109 in the sleeves 104. A boss portion 113 at the top of the fork in the lever 56 is used as the operating contact point with the lever 53 and associated parts. Except for this contact point, there is no actual connection between the two levers 53 and 56 so that the lever 53 may be moved independently of lever 56 during. part of its movement. A

The outer lever 53 is of different shape from the lever 56 but is also a forked, double end bell crank, see Figs.

'7, 8 and 9. A forked opening 114 is sufiiciently. larger to permit lever 53 to operate outside of lever 56 while being attached to the same pivots 52. Another difference between the outer lever 53 and the inner lever 56 is that bell crank lever ends 115 and 116. are single on only one leg of the fork and are provided with pads 117 and'1-18,respectively, instead of bosses as onthe lever 56. These pads 117 and 118 are the contact points with. the ends of push rods 54. and 55. At the top of the fork in lever 53 is a drilled boss 119. to which a spring rod 59 is pinned while also extending from. thetop of the fork in the lever 53 are two ears 120 and 121 which are threaded to receive contact screws 60 and 61, Fig. 4, for contacting the boss 113 on the lever 56 to move such lever 53 by the lever 56.

Referring back to Fig. 4, the yoke engaging end of the spring rod 59 is, pinned tothe lever 53 while the shank end of the rod slides in a hole in pivot pin 62 which is journalled in the upper portion of the housing cover 46. Surrounding the spring rod 59, so as to bring force to bear on the yoke engaging end of the rod, is.

the compression spring 57 with its opposite end seated on pivot pin 62. The spring 57 is assembled with sufficient initial compression to shift the two valves 47 and 48. when the spring and associated means are properly positioned. As the lever 53 is oscillated left andv right of center by the push rods 54 and 55, the shank of the rod 59 slides in the central hole of pivot pin 62 and this pin 62 oscillates on its center as rod 59 changes; its angular position from left to right and vice versa.

It is apparent from the foregoing description and sketches that as the outer lever 53, Fig. 4, is moved from the left hand position shown, toward the right, and as the pin of spring rod 59 comes into alignment with pivots 52 and 62 and then just after passing through this center alignment, that the spring 57 will snap lever 53 to the opposite right hand position. In doing so, contact screw 60 which, will have made contact with the boss 113 on lever 56 at the same center alignment point will also snap lever 56 to the right and thus reverse the positions of valves 47 and 48 and consequently the action of the power cylinders. The space provided between the contact screws 60 and 61 is utilized. not, only for the snap action movement but also to permit moving the lever 53 by the power cylinders through the push rods 54 and 55- operating alternately on the pad arms of lever 53. Each power cylinder as it makes its stroke, applying power to the feed shaft, also moves, through its corresponding push rod, the lever 53 to the center or snap over position which is timed to take place; at the end of thepower stroke. The contact screws 60v and 61 are adjustable so as to provide the means of exactly timing the piston stroke end points with the air valve shift point.

A compressed air suply line 122 connects to the inlet of the valve 29, while conduit 123 connects the valve 47 to the power cylinder 27 and conduit 124 connects the valve 48 to the power cylinder 124, Fig. 1 1. Any suitable linkage such as bell crank levers 125 and links 126 connect the piston rods 24 and 25 to the pawl carriers, or shaftactuation, means shown to provide at, least substantially constant arcuate actuations for the shaft 9. Of course, more than two power cylinders may be used, if desired, to provide smoother actuation of the shaft. Likewise, other drive means such as pressure diaphragms may be used in place of the power cylinders. Links 127 connect the bell crank levers125 to the push rods 54 and 55 to control feed of compressed air to the power cylinders 26 and 27 for operating the movable power output means thereof.

It will be realized that the inertia of the shaft 9 and associated parts will aid in effecting smooth operation of the apparatus of the invention from the substantially continuous actuation thereof by thepower cylinders that have, in effect, a continuous power output. By use of more than two power cylinders, air may be fed to two cylinders at one time and be disconnected from, the cylin: ders at different instances to provide a continuous power output for driving the shaft 9 and connected means.

Whenthe air valves are shifted, air from the supply reservoirs under pressurewillrbe fed to the cylinder about to begin its power stroke and at the same time, the ex haust will be opened to the cylinder just, completing its power stroke. To prevent the loss of tension in, the pull down chains, the air being, exhausted from, the: cylinder into housing 46 can be controlled by, the use or a metering valve 63 so that the load will be transferred smoothly from the one cylinder to the other. J

outlet. The rate at which the feed was being used and therefore the number of air valve shifts per unit of time would be audible by the sounding of the whistle and would serve to guide the driller even though he were engaged in some task that required his being away from the machine controls. Of course, if it stopped whistling he would know it had stopped drilling.

From the foregoing, it will be seen that a novel, efficient type of power feed means using compressed air has been provided for a rotary drill so that the objects of the invention have been achieved.

While one complete embodiment of the invention has been disclosed herein, it will be appreciated that modification of this particular embodiment of the invention may be resorted to without departing from the scope of the invention as defined in the appended claims.

The present application is a continuation of my copending application S.N. 358,400 filed May 29, 1953 entitled Fluid Motor and now abandoned.

I claim:

1. The combination in rotatable well drilling apparatus of a drill bit, a length of drill pipe secured thereto, a kelly secured at its lower end to the drill pipe, a rotatable driving head receiving the kelly in splined relation, a swivel secured directly to the upper end of the kelly, a guide frame extending parallel to the kelly and supporting the driving head, a yoke engaging the swivel and slid ably supported in the frame for movement toward the driving head, said yoke and said driving head holding said kelly in vertical alignment by guiding it at two positions therealong, a shaft rotatably mounted in the frame near the lower end of the frame and at right angles to the kelly but substantially in the plane of the kelly, spaced sprockets on said shaft one on each side of the kelly, endless chain means surrounding the sprockets and secured at one point in their length to the yoke, rotatable means near the top of the frame supporting the chainmeans opposite the sprockets, a rotatable member for driving said shaft, a clutch releasably connecting the member to the shaft, a pair of one-way ratchet clutches on the rotatable member, a pair of reciprocating pistons and air cylinders, the piston of each cylinder being connected to one one-way clutch to advance it step by step in the direction to rotate the rotatablemember and the shaft, spring means for retracting the ratchet clutches, and reciprocating reversing valve means adapted to alternately connect the cylinders to a source of compressed air and to exhaust respectively to oppositely reciprocate them and forcibly feed the drill bit axially.

2. The combination in rotatable well drilling apparatus of a kelly, a drill bit adapted to be secured to the lower end of the kelly, a rotatable driving head receiving the kelly in rotational driving relation, a swivel secured directly to the upper end of the kelly, a guide lframe extending parallel to the kelly, in an upward direction from the driving head, a yoke engaging the swivel and slidably supported in the frame for movement toward the driving head, said driving head and said yoke providing spaced bearings for holding said kelly in vertical alignment, a shaft rotatably mounted in the frame at right angles to the kelly but substantially in the plane of the kelly, sprocket means on said shaft, endless chain means surrounding the sprocket means and secured at one point in their length to the yoke, rotatable means near the top of the frame supporting the chain means opposite the sprocket means, a pair of one-way ratchet clutches connected to the shaft, a pair of reciprocating pistons and air cylinders, the piston of each cylinder being connected to one one-way clutch to advance it step by step in the direction to rotate the shaft, spring means to retract the ratchet clutches, and reciprocating reversing valve means adapted to alternately connect the cylinders to a source of compressed air and to exhaust respectively to oppositely reciprocate them and forcibly feed the kelly and drill bit axially.

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