US2865604A - Automatic cable-clamping mechanism for cable-tool drill - Google Patents

Description

. Dec. 23, 1958 A. c. HAISCH AUTOMATIC CABLE-CLAMPING MECHANISM FOR CABLE-TOOL DRILL 4 Sheets-Sheet 1 Filed Feb. 13, 1956 ALBERT c. HAISCH,

INVENTOR,

BY ATTORNEY Dec. 23, 1958 A. c. HAISCH' 2,865,604

AUTOMATIC CABLE-CLAMPING MECHANISM FOR CABLE-TOOL DRILL Filed Feb. 1a, 1956.

4 Sheets-Sheet 2 ALBERT c. HAlscH,

INVENTOR,

1 BY WAA Na 26 a ATTORNEY A. C. HAISCH AUTOMATIC CABLE-CLAMPING MECHANISM FOR CABLE-TOOL DRILL Filed Feb. 13, 1956 4 Sheets-Sheet 3 a b m wv. M 2

4 a B Z u M@ x M. w B 0 m M w M. U 4 on u 0 T llllll 6 |l||l||l||l|||W- an 2 w w 7 FIG. 8.

ALBERT c. HAISCH,

INVENTOR BY 9k ATTORNEY Dec. 23, 1958 A. c. HAISCH 2,865,604

AUTOMATIC CABLE-CLAMPING MECHANISM FOR CABLE-TOOL DRILL Filed Feb. 13, 1956 4 Sheets-Sheet 4 Fig. 9. 3!

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ALBERT C. HAISCH,

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'BYQJMAWMSW ATTORNEY 2,65,604 Patented Dec. 23, 1958 free AUTOMATIC CABLE-CLAMPIN G MECHANISM FOR CABLE-TOOL DRILL Albert C. Haisch, South Milwaukee, Wis., assignor to Eneyrus-Erie Company, South Milwaukee, Wis., a cor poration of Delaware Application February 13, 1956, Serial No. 565,145

7 Claims. (Cl. 255-11) This invention relates to new and useful improvements in a cable-clamping mechanism for spudder-type cabletool drills.

Cable-tool drills as such, are well known in the art.

In such drills, a cable passes from a winch drum on.

the main frame, around a heel sheave at or near the pivot of a spudding beam, then under a spudding sheave at the oscillating end of the spudding beam, then over a crown sheave at the upper end of a mast and then vertically downward into the hole which is being drilled in the ground. Suspended at the lower end of this cable is a string of percussion drill tools, terminating in a bit. The spudding beam is oscillated by a pitman, actuated by a rotating crank. The oscillating motion of the spudding sheave of the spudding beam (hereinafter called the spudding-beam cycle) transmits vertical reciprocating drilling motion to the drill tools (hereinafter called the drill-tool cycle). This motion is called spudding.

During drilling, the spudding-beam cycle is approximately 180 degrees out of phase with the drill-tool cycle, i. e., when the spudding beam is in its uppermost position the drill tools are at their lowest position, and vice versa. The cycle of the spudding beam starts from rest at its upper position, accelerates downward reaching its maximum velocity at approximately the midpoint of its downward stroke, decelerates the remainder of the downward stroke and comes to rest at its lower position. It then accelerates upward reaching its maximum velocity at approximately the midpoint of its upward stroke, decelerates for the remainder of its upward stroke and comes to rest at its upper position.

If the rotating crank is operated slowly (i. e., at a speed such that the upward acceleration of the spudding sheave during the first half of its upward movement is equal to or less than the downward acceleration under gravity of the drill tools) the drill tools will follow a cycle exactly 180 degrees out of phase with the abovedescribed spudding-beam cycle, but at such speed the bit will not do useful Work because the drill tools will be brought to rest by the spudding mechanism instead of by impact at the bottom of the hole. If useful work is to be obtained from the bit, it is necessary to operate the rotating crank at a relatively-high speed (i. e., at a speed such that (a) the upward acceleration of the spudding sheave during the first half of its upward movement is greater than the downward acceleration under gravity of the drill tools and (b) slack developed in the cable by the spudding sheave overtravelling the drill tools, as a result to such difference in their respective accelerations, is sufficiently great that at least some of such slack is maintained until an instant before drill-bit impact and reversal of the spudding sheave). When operated at such desired high speed, the spudding-beam cycle will lead that of the drill tools and not retard them on their downward stroke. When operated in this manner, the

spudding beam begins tightening the cable (i. e., eliminating cable slack) an instant before bit impact at the bottom of the hole. Thus, the drill cable is maintained taut during the upward stroke of the drill tools, in which they are accelerated to maximum upward velocity near the mid;oint of the stroke and thereafter decelerated under influence of gravity until they come to rest at the top of the stroke. Thereafter, as the drill tools accelerate downward from the top of their stroke, the spudding beam accelerates upwardly but faster than the drill tools, thus allowing the drill tools to fall freely under gravity.

It is desirable, throughout the downward stroke of the drill tools, that they not be retarded by the spudding beam, and that they strike the bottom of the hole with maximum impact. To accomplish this, the spudding beam must initially overtravel the tools and accumulate sufficienLslack cable so that only in the final stages of spudding-beam deceleration will the drill tools overtake the spudding beam and absorb the cable slack. Thus, during the downward stroke of the tools, the drill cable is taut at the beginning of the stroke, but accumulates slack during fall of the tools to approximately the midpoint of their downward stroke, at which point the cableslack diminishes, and the cable is finally tightened an instant before impact of the tools in the bottom of the hole.

This periodic slackening of the cable creates the following problem. As slack cable accumulates, the slack extends to the winch drum causing cable coils on the drum to expand and loosen. An instant before the drill tools reach the bottom of the hole, the slack cable is abruptly tightened. Repeated loosening and tightening of cable on the drum produces wear on the drum surface and on the cable.

Various devices have been used in the past to clamp the cable at some point between the drum and the heel sheave in an attempt to keep the coils of cable tight and in their proper position on the drum. In such a device, the clamp is engaged at all times even if not needed. The clamp thus serves no useful purpose while raising or lowering the drill tools. Furthermore the clamp and cable are subject to wear when the cable slides through the clamp, and on this account the clamp requires frequent adjustment.

Other devices have been used to hold the cable against the heel sheave to resist accumulation of slack cable on the winch drum during spudding. These latter devices are usually provided with manual controls to release the cable-holding means when not required. Such manual controls require continuous attention of the operator.

Cable-tool drills have more recently generally been provided with an automatic-feed mechanism, which automatically unspools cable from the drum without interruption of spudding to supply the drill tools with additional cable as the depth of the hole increases.

In such devices, automatic feeding occurs during that phase of the spudding cycle when cable tension is at a maximum, namely, at the time of tool pick-up at or immediately following impact.

Accordingly, it is the principal object of the present invention to provide a self-engaging and self-disengaging slack-holding device synchronized with the spudding mechanism which will overcome the above objections.

A further object of this invention is to provide an automatic slack-holding device, which will be automatically engaged when cable slack normally occurs during spud ding, and which will be automatically disengaged when automatic feeding occurs during spudding and when tools are raised and lowered by the winch.

In addition to the above-stated principal objects, a number of novel and useful details have been worked out, which will be readily evident as the description progresses.

The present invention consists in the novel parts and in the combination and arrangement thereof, which are defined in the appended claims, of which four embodiments are exemplified in the accompanying drawings, hereinafter particularly described and explained.

Throughout the description, the same reference number is applied to the same member or to similar members.

Figure 1 is a side elevation of a spudder-type cable tool drill embodying one form of the present invention.

Figure 2 is a side elevation partly in section, of the first embodiment of the invention.

Figure 2A is an enlarged cross-section view of the brake, applicable to all embodiments of the invention, taken along lines 2A-2A of Figure 2.

Figure 3 is a plan view of the drive machinery of Figure 1 taken along lines 33 of Figure 1.

Figure 4 is a side elevation, partly in section, of the second embodiment of the invention.

Figure 4A is a section of Figure 4 showing a second variant of the second embodiment of the invention.

Figure 5 is a side elevation, partly in section, of the third embodiment of the invention.

Figure 6 is a side elevation, partly in section, of the fourth embodiment of the invention.

Figure 7 is a front elevation, partly in section, of the hydraulic control valve of the second embodiment of the invention shown in its brake-setting position.

Figure 8 is a front elevation, partly in section, of the same valve as Figure 7 shown in its alternative brakeunsetting position.

Figure 9 is a schematic view showing the hydraulic circuits of the second embodiment of the invention.

Figure 10 is a schematic view showing the electrical circuits of the third embodiment of the invention.

Figure ll is a schematic view showing the air circuits of the fourth embodiment of the invention.

Referring to Figures 1 and 3, a main frame 11, is I supported by creeping traction 12.

Frame 11 supports a motor 14; a drive shaft 17 driven by the motor through belt 14a and associated pulleys;

a winch drum 16 drivable by drive shaft 17 through clutch 32, pinion 16a and gear 16b; and spudding gear 19 drivable by drive shaft 17 through clutch 33 and pinion 18.

The winch 16 is controlled by means of a clutch 32, a conventional brake (not shown), and control levers (not shown). The spudding gear is controlled by means of a clutch 33 and control levers (not shown).

From winch 16, a cable 20 passes around heel sheave 21, rotatably mounted at the fulcrum end of spudding beam 23 on shaft 24, then under spudding sheave 22 rotatably mounted near the reciprocating end of spudding beam 23, then over crown-sheave 25 supported at the top of mast 13 by housing 25a, and then down to drill-string 15 terminating in a bit (not shown).

Crown-sheave 25 is mounted in a housing 25a, which is arranged in any convenient manner to slide up and down with respect to the mast 13. This housing 25a rests on alternately spaced steel and rubber discs 2511, which thus furnish a resilient support for crown-sheave 25. (See U. S. Patents No. 1,750,826, issued March 18, 1930, to George R. Watson, and No. 2,587,638, issued March 4, 1952, to Johann H. Meier.) Thus crownsheave 25, like sheave 22, constitutes a cable cooperating means that oscillates with the cable during the drilling cycle.

Pitman 28 is connected to spud-ding-gear 19 by crankpin 29 and to spudding beam 23 by pin 30. A cam 31 is keyed to shaft 27 for use with the embodiments of Figures 4, 4A, 6, 7, 8, 9 and 11, hereinafter described.

Power is transmitted from motor 14 to spudding beam 23 through the belt 14a, drive shaft 17, clutch 33, spud:-

4 ding pinion 18, spudding gear 19, shaft 27, crank-pin 29, and pitman 28.

The novel parts of the invention will now be de scribed.

Figures 2 and 2A show the first embodiment of this invention.

Heel sheave 21 is mounted for rotation and free lateral sliding on shaft 24. Heel-sheave yoke 34 which consists of lateral spacers 34a and arcuate spacer plate 34b interconnecting side plates 34c and 34d on either side of heel-sheave 21, is pivotally mounted on shaft 24 in a conventional manner to permit the yoke 34 to slide laterally on shaft 24 and to permit shaft 24 to pivot relative to yoke 34 during spudding. Yoke 34 is held against rotation in either direction about shaft 24 relative to frame 11 by transverse angle guides 11a and 11b which are attached to the frame 11 and engage and thereby restrict fore-and-aft movement but permit lateral movement thereon of roller 26 mounted on the lower end of yoke 34. Inside heel-sheave yoke 34 is brake-shoe 35 pivotally connected to said yoke 34 at its lower end by pin 40. The inner portion of brakeshoe 35 (Figure 2A) covers a substantial part of the span of the brake-shoe arc, and hardened surface 36 on said portion opposes groove 21a of heel-sheave 21 for engagement with cable 20. Said inner portion of brake-shoe 35 fits into cable-groove 21a in such a manner that when the brake is unset, clearance a between hardened surface 36 of brake-shoe 35 and cable 20 is less than clearances b and c between brake-shoe 35 and heel-sheave 21. Upon setting the brake, only hardened surface 36 engages cable 20 in cable-groove 21a of heel-sheave 21.

Brake-shoe 35 could be constructed to engage with both heel-sheave 21 and cable 20 in cable-groove 21a, but after wear on hardened surface 36, brake-shoe 35 would engage only heel-sheave 21, and cable 20 would then slip through cable-groove 21a with resulting slack cable between heel-sheave 21 and winch 16.

In Figure 2, spring assembly 39, which includes spring housing 39a, compression spring 41, and axially adjustable seat 3915 for the inner end of spring 41, is mounted on the upper end of heel-sheave yoke 34. The outer end of spring 41 fits against shoulder 38, which is an upper extension of brake-shoe 35. At the upper end of brake-shoe 35, opposite shoulder 38, is mounted roller 37. Mounted on spudding beam 23 near its fulcrum is support 42 on which is mounted striking bar 43 which is positioned to engage roller 37 when spudding beam 23 approaches its upper position. When spudding beam 23 is in its lowered position, the bar 43 is disengaged from roller 37 so that the reaction of compression spring 41 on shoulder 38 forces brake shoe 35 against cable 20 in cable-groove 21a of heel-sheave 21 and clamps cable 20 between the heel-sheave 21 and brake shoe 35. As spudding beam 23 approaches its upper position, striking bar 43 then contacts roller 37. Continued rising of spudding beam 23 rotates brakeshoe 35 about pin 40 raising brake-shoe 35 off cake 20 and compresses spring 41 still further (position of brake shown in Figures 2 and 2A). As spudding beam 23 lowers, bar 43 disengages roller 37 and brake-shoe 35 again contacts cable 20 at surface 36 in cable-groove 21a of heel-sheave 21 and prevents slack cable from sliding therethrough.

During spudding, spudding beam 23 oscillates up and down, being pivoted on shaft 24 by crank-pin 29 and pitman 28 (Figure 1). When crank-pin 29 is within a range of upper positions, predetermined by the position of striking bar 43 on the spudding beam, on either side ward-stroke (solid outline in Figures 1 and-2),-ittends to pick up drill tools 15 before they reach theend of their downward stroke and impact at the-bottom of the hole. At the instant of impact,'whichoccurs an instant after cable slack has been taken up and the immediately subsequent reversal of the spudding sheave and pitman at the top of the spudding-beam cycle, considerable tension has developed in cable 20, depending on how far drill tools 15 have had to overreach, thereby stretching the cable and compressing the shock absorber 25b to strike the bottom of the hole and expand their kinetic energy. The high load in cable, 20 at impact produces a shock wave along the length of said cable causing the winch-drum brake (not shown) to momentarily slip and feed off a length of cable 20. The amount of feed is dependent on the intensity of the shock wave and the setting of said winch-drum brake. Alternatively a positive automatic feed may be produced responsive to compression of the shock absorber 25b at impact of the drill bit, as shown and described in detail in U. S. Patent No. 2,587,638, to J. H. Meier.

As crank-pin 29 passes its top dead-center position, striking bar 43 and its support 42 move to the right, and spring 41 tends to reset the brake. When crankpin 29 is approximately 40 degrees past top-dead center position, striking bar 43 on support 42 is disengaged from roller 37 and brake-shoe 35 is fully set.

The above-described setting and nnsetting of the brake occurs with each oscillation of the spudding beam. When clutch 33 (Figure 3) is disengaged to stop spudding, the weight of drill-string 15 (Figure 1) will lift spudding beam 23 to its uppermost position. With the spudding beam in this position, brake-shoe 35 is unset, and winch 16 may be engaged to at will raise or lower the drill string. Once the weight of drill-string 15 is removed from cable 20, spudding beam 23 will fall to its lower position (dotted outline in Figures 1 and 2) under its own weight, and brake-shoe 35 will again set to prevent slack line from backing up and unwinding on winch 16.

Figures 2A, 4, 7, 8 and 9 show the second embodiment of this invention. Heel-sheave 34, roller 26, angle guides 11a and 11b, brake-shoe 35, hardened surface 36, cable 20, spudding beam 23, pitman 28, crank-pin 29 and spudding gear 19, bear the same relationship to each other as they did in the first embodiment.

A double-acting cylinder-piston assembly 44 is pinconnected to heel-sheave yoke 34 by pin 45. Piston rod 46 is pin-connected to the live end of brake-shoe 35 by pin 47.

Cylinder 48 of said cylinder-piston assembly is connected into a hydraulic system for actuation of piston 79 in the following manner:

In Figure 9, a fluid sump 49 is connected by conduit 50 to fluid pump 51, which supplies fluid under pressure to the system. A control valve 53 (detailed in Figures 7 and 8) is mounted on the main frame 11 by bracket 52 secured by studs 54. The control valve 53 has a valve body 55 with inlet port 56, upper and lower exhaust ports 57a and 57b, exhaust manifold 57, and valve ports 58 and 59. Valve spool 60, having upper and lower annular rings 62 and 68, is fitted for longitudinal movement inside valve body 55. Spring 61 is seated at the upper end of valve body 55 and biases valve-spool 613 downwardly in Figures 7 and 8.

In Figures 7 and 8, pump 51 is connected to valve inlet port 56 by fluid conduit 72. Fluid conduit 73 forms a fluid connection between valve port 58 and cylinder port 71 (Figure 4) on one side of cylinder 48, and fluid conduit 74 forms a fluid connection between valve port 59 and cylinder port 76 (Figure 4) on the opposite side of cylinder 48. Fluid conduit 75 connects exhaust manifold 57 and sump 49 (Figure 9). Relief Valve 77 is interposed in fluid conduit 72 near pump 51.

One end of conduit 78 is connected to relief valve 77 and its other end is T-co-nnected to fluid conduit 75.

Valve rod 63 (Figures 7 and 8'), built integral with valve spool 60 extends out of gland 64 of valve 53, and has cam follower 65 rotatably mounted on its end by yoke 66 and pin 67. Cam follower 65 rides on cam 31. Cam 31 is keyed on shaft 27 and is synchronized with crank-pin 29 (Figure 1) on spudding gear 19, so that the outer point on the cam surface 31 will reach topdead center the instant crank-pin 29 is at top-dead center. Accordingly, mention of top-dead center posi tion will hereinafter apply equally well to the position of both cam and crank. Top-dead center position, also will hereinafter correspond to the highest point of oscillation of spudding beam 23 (solid outline, Figures 1, 2, 4, 5, and 6).

Referring now to Figure 7, valve spring 61, retracted between the upper end of valve body 55 and the upper end of valve spool 60, normally holds said spool set in its lower position. In this position, upper annular ring 62 of valve spool 60 directs pressure fluid entering at inlet port 56 downward into valve port 59, while lower annular ring 68 of valve spool 60 blocks lower exhaust port 57b leading to exhaust manifold 57, and upper annular ring 62 directs exhaust fluid from the cylinder entering at valve port 58 into upper exhaust port 57a.

Upon rotation of cam 31 to within approximately 40 degrees of top-dead center (setting, Figure 8), the rise in pitch of cam 31 will shift valve rod 63 and valve spool 60 upward, further compressing valve spring 61. With valve spool 61) in this position, its lower annular ring 68 directs pressure fluid from inlet port 56 into cylinder port 58, while its upper annular ring 6 2 blocks upper exhaust port 57a leading to exhaust manifold 57, and lower annular ring 68 directs exhaust fluid from the cylinder enterin at valve port 59 into exhaust port 5712.

After cam 31 rotates approximately 40 degrees past its top-dead center position, the drop in pitch of cam 31 allows cam follower 65 to fall, and valve spring 61 shifts valve spool 60 back to the position shown in Figure 7.

This second embodiment of the invention operates in the following manner.

If the spudding-mechanism is disengaged and drillstring 15 is suspended on cable 20, the weight of said drill string will hold spudding beam 23 in its uppermost position (Figure 1), and crank-pin 29 and cam 31 will be at top-dead center position (Figure 8). Cam 31 then sets control valve 53 to interconnect fluid conduits 72 and '73, respectively, and direct fluid under pressure from the pump to cylinder port 71 on cylinder 48 (Figure 4). Pressure fluid then forces piston 79 to the left actuating piston-rod 46 to unset brake shoe 35.

At this setting of control valve 53, valve spool 66 directs exhaust fluid from cylinder port 76 on cylinder 48 through fluid conduits 74 and 75 to the sump.

Spudding is started by engaging clutch 33 (Figure 3) causing counterclockwise rotation of spudding gear 19,, crank-pin 29, and cam 31 (Figure 1). After cam 31 rotates counterclockwise 40 degrees, cam follower 65 and valve spool 60 will shift under force of valve spring 61, to the position shown in Figure 7. In this position, valve spool 61) connects fluid circuits 72 and 74, respectively, directing fluid under pressure from the pump to cylinder port 76 on cylinder 48 (Figure 4). Pressure fluid now forces piston 79 to the right actuating piston rod 46 to set brake shoe 35 on cable 20 in cable-groove 21a during the remainder of pick-up of the drill string.

At the same time, valve spool 60 connects fluid conduits 72 and 75, permitting fluid to exhaust from cylinder 48 through cylinder port 71 to the sump.

Brake shoe 35 remains set until cam 31 thenadvances to within approximately 40 degrees of top-dead center position. At this point, cam follower 65 moves upwardly under .force ofcam 31, and valve spool 66 is shifted 7 to the brake unsetting position (Figure 8), previously described.

Thus, the brake is automatically set and unset, responsive to the spudding mechanism during the drilling cycle. The brake is unset during the lower stage of fall of the bit and the initial stage of raise of the bit. It is during this period of the spudding cycle that cable is automatically fed to the drill string. The brake remains set at all other times during the spudding cycle.

A second variant of this embodiment is shown in Fig ure 4A.

The structure of this variant is the same as shown in Figures 4, 7, 8 and 9 previously described, except that cylinder-piston assembly 44a is single-acting instead of double-acting, and fluid conduit 74 is now connected to sump 49 rather than to the left end of the cylinder.

Spring-assembly 69, fitted over piston rod 461:, is retracted between the end of cylinder-piston assembly 44a and nut 70 threaded on the outer end of piston rod 465:. The force of spring-assembly 69 normally sets brake shoe 35 on cable in cable-groove 21a of heel-sheave 21.

Accordingly when valve spool 60 is in the lowered position (Figure 7), fluid from pump 51 and fluid conduit 72 will be directed back to the sump through valve body 55, exhaust manifold 57, and fluid conduit 74 (now connected to the sump). Fluid exhausted from cylinder 48a (Figure 4A) through cylinder port 71 will flow to the sump by way of fluid conduit 73, valve body 55, exhaust manifold 57 and fluid conduit 75. Spring assembly 69 holds brake shoe set.

When valve-spool is shifted to its upper position (Figure 8) by cam 31, fluid will flow from pump 51, through fluid conduit 72, valve body 55, fluid conduit 73, cylinder port 71 (Figure 4A), and into cylinder 48a to force piston 79 and piston rod 46a to the left unsetting brake shoe 35. No fluid will be exhausted from cylinder 48a at this setting, therefore, fluid conduits 74 and 75 (which now lead to the sump), are interconnected by valve spool 60.

The third embodiment of this invention is shown in Figures 5, 2A and 10.

In this embodiment, brake shoe 35, hardened surface 36, cable 20, spudding beam 23, pitman 28, crank-pin 29 and spudding gear 19 bear the same relationship to each other, as they did in the first embodiment.

In Figure 5, heel-sheave yoke 93 is supported to slide axially on shaft 24, the same as brake housing 34 described under the first embodiment. Electric solenoid is pivotally connected at one end to heel-sheave yoke 93 at hanger 81 by pin 82, and at its other end to brake lever-arm 83 by pin 84. contactor support 85, which is an L-shaped piece of spring steel, is fastened to heelsheave yoke 93 near solenoid 80. Contactor support 85 has an electrical contactor 86 fastened to its lower end and wire 87, attached to electrical contactor 86, extends along contactor support 85 to a connection on terminal post 88. Terminal post 88 is electrically connected to one side of solenoid 80 by wire 89. The other side of solenoid 80 is electrically connected to one side of generator 90 (Figure 10) by wire 91. The other side of generator 90 is electrically connected to a cooperating electrical contactor 92 by wire 97. Contactor 92 is attached to support 42 mounted on spudding beam 23, and is engageable with electrical contactor 86.

Thus electrical contactors 86 and 92 comprise an electrical switch for closing the circuit to solenoid 89.

Spring assembly 39 is mounted on heel-sheave yoke 93 (Figure 5). Spring 41 is compressed against brake-shoe 35 to normally hold the brake set on cable 29 in cable groove 21a of heel-sheave 21.

After spudding beam 23 pivots upwardly to a point where crank-pin 29 is approximately 40 degrees from top-dead center (Figure 1), electrical contactor 92 (Figure 5) carried by spudding beam 23 engages electrical contactor 86, closing the switch and the circuit to solenoid 80. Solenoid 80, thus electrically energized, retracts and unsets brake shoe 35. As spudding beam 23 continues to pivot upwardly, contactor support 85 will bend to the left, and maintain switch 86-92 closed.

When crank-pin 29 passes top-dead center, spudding beam 32 and electrical contactor 92 reverse direction. The spring of contactor support 85 will hold switch 86-92 closed until crank-pin 29 is approximately 40 degrees past top-dead center, whereupon electrical contactors 86 and 92 separate to open the switch and deenergize solenoid 80. Spring assembly 39 then resets the brake.

Once spudding has stopped and drill-string 15 is suspended on cable 20, spudding beam 23 will automatically pivot to its uppermost position under the weight of the drill string, and switch 86--92 will close. Thus, the brake is unset to allow unrestricted use of winch 16.

The fourth embodiment of this invention is shown in Figures 6, 2A and 11.

Here again, heel-sheave yoke 34, brake shoe 35, roller 26, angle guides 11a and 11b, hardened surface 36, cable 20, spudding beam 23, pitman 28, crank-pin 29, and spudding gear 19 bear the same relationship to each other as they did in the first embodiment.

In Figure 6, a conventional single-acting vacuum-actuated diaphragm 94 is mounted on top of heel-sheave yoke 34. Plunger-rod 95 is pin-connected by pin 98 to link 96 bolted on the live end of brake-shoe 35. A flexible conduit 99 is connected to diaphragm 94 at port 100.

Spring assembly 39 functions in the same manner for normally holding the brake set on cable 20 in cable groove 21a of heel-sheave 21, as previously described for the first and third embodiments.

Turning to Figure 11, vacuum pump 10]. has an airtight connection with vacuum tank 162 through conduit 103. A conventional two-way valve 107 is mounted on main frame 11 near the end of shaft 27. Cam 31 is keyed to the end of shaft 27, as previously described for the second embodiment. Cam arm 104 is pivoted at one end on frame 11 by pin 105. Cam follower 65, which rides on cam 31, is pivoted on the other end of cam arm 104 by pin 109. Valve rod 106 of valve 107 is pinconnected to earn arm 104.

Conduit 108 interconnects vacuum tank 102 and valve 107, and conduit 99 interconnects valve 107 and diaphragm 94. Valve 107 is spring loaded to normally close off conduit 168 and vent conduit 99 to the atmosphere, whenever cam follower 65 rides the depressed surface on cam 31. This condition occurs between approximately 40 degrees past and approximately 40 degrees before top-dead center position of cam 31. When cam 31 is within 40 degrees of its top-dead center position, cam follower 65 rises and pivots cam arm 194 counterclockwise about pin 195, shifting valve 107 to interconnect conduits 108 and 99. Diaphragm 94 is then vacuum-actuated to retract, thereby shifting its plunger rod 95 to the left unsetting the brake.

When spudding is stopped, the weight of the drill string rotates crank-pin 29 and cam 31 to their top-dead center position. Thus, cam 31 shifts valve 107 to its other position, and diaphragm 94 unsets the brake. Winch 16 may then be operated to raise or lower the drill string.

This fourth embodiment need not be limited to a vacuum system, but a compressed air system is readily adaptable to the embodiment by replacing the vacuum pump and air diaphragm with equivalent air equipment, such as an air' compressor and air motor, respectively.

It will be noted that in all embodiments of this invention the sheave 21 and its cooperating brake 35 constitute in effect a cable-clamping means for clamping the cable 20 in fixed relation to the drill frame 11, said cableclamping means being actuable to so clamp the cable in response to predetermined positioning of the spudding means 19, 22--24, 27-30; and that accordingly the cable clamping means could if desired be located on other parts of the drill frame than the heel of the spudding beam, the latter arrangement being merely a convenient location in the preferred construction, and other forms of rotatable or nonrotatable cable-receiving or cableengaging devices could be substituted for the sheave 21 to cooperate with the braking elements of the cableclamping means.

It will further be noted that the cable-clamping means is actuated to unclamp the cable during a predetermined portion of the drilling cycle responsive to oscillation of cable-cooperating means, such as the spudding means, which oscillates with the cable during the drilling cycle; and that although this response is preferably achieved by actuating the clamping means responsive to cyclical positioning of the spudding means, the same result can be achieved by actuation responsive to cyclical positioning of any other element that cooperates with the cable to oscillate therewith in the same or in a related cycle, such as, for example the yieldably-mounted oscillating sheave 25.

It can be readily seen that the above-described four embodiments provide simple and efficient automatic means for holding the drill cable taut during spudding and prevent it from loosening and tightening on the Winch drum,

but will: (1) Release the cable for automatic feed to the drill string during each spudding cycle, just prior to bottoming the bit in the drill hole, and (2) Release the cable when spudding is stopped to allow the winch to operate efliciently and freely.

Throughout the description of the four embodiments of this invention, the angular displacement of the crank and, in the second and fourth embodiments, the cam is designated as 40 degrees before their top-dead center posi tion to 40 degrees past their top-dead center position, during which time the brake is unset. Let it be understood, that this angular displacement may be varied, with varied results in brake setting and unsetting, by making one or more of the following adjustments: (1) In the bracket on the spudding beam (first and third embodiments), (2) In the crank and pitman (all embodiments), (3) In variation of the Width of the rise of the cam (second and fourth embodiments) and (4) In the synchronization of crank and cam (second and fourth embodiments).

The first embodiment is the preferred showing of this invention, because of its simplicity and ease of adjustment; however, all five forms of this invention will operate efliciently.

Having now described and illustrated five forms of the invention, it is to be understood that the invention is not to be limited to the specific forms or arrangement of parts herein described and shown.

What is claimed is:

1. In an automatic cable-clamping mechanism for a cable-tool drill having: a drill frame; a cable; a winch operatively connected to the cable for winding in or paying out the cable; a drill bit suspended by the cable; and spudding means for imparting vertical reciprocating motion to the cable including a spudding beam pivotally mounted on the frame, a heel sheave about which the cable is reeved pivotally mounted adjacent the pivot of the spudding beam, a spudding sheave about which the cable is reeved and rotatably mounted on the spudding beam and spaced from said pivot, and drive means operatively connected to the spudding beam for reciprocating the spudding beam; the combination therewith of: a brake supported by the drill frame adjacent the heel sheave and engageable with the cable for braking said heel sheave and cable; brake-setting means connected to the brake and the frame for normally setting the brake; and means actuated in response to position of the spudding means for automatically unsetting the brake when the spudding beam reaches a position in advance of its normal reversal position from a bit-lowering to a bitraising stroke and thereafter holding said brake unset during a predetermined portion of its cycle.

2. An automatic cable-clamping mechanism for a cabletool drill according to claim 1, further characterized by the fact that the means to automatically unset the brake includes a reciprocating element supported by and reciprocable with the spudding beam and positioned thereon to engage the brake to unset the brake when the spudding beam reaches its advance position.

3. An automatic cable-clamping mechanism for a cabletool drill according to claim 1, further characterized by the fact that the means to automatically unset the brake includes: a fluid motor connected between the drill frame and the brake, and fluid control means for said motor; said fluid control means including a fluid-control circuit, a reciprocating cam actuated by the spudding means, and a control valve in said circuit actuated by said cam.

4. An automatic cable-clamping mechanism for a cabletool drill according to claim 3, further characterized by the fact that the fluid motor is a hydraulic pressureactuated ram.

5. An automatic cable-clamping mechanism for a cabletool drill according to claim 3, further characterized by the fact that the fluid motor is a pneumatic vacuumactuated air-diaphragm type ram.

6. An automatic cable-clamping mechanism for a cabletool drill according to claim 1, further characterized by the fact that the means to automatically unset the brake includes: an electric motor connected between the drill frame and the brake, and control means for said motor; said control means including an electric circuit and a switch in said circuit actuated by said spudding means.

7. In an automatic cable-clamping mechanism for a cable tool drill, the combination of: a drill frame; a vertically reciprocable drill tool cable; a winch for winding in and paying out the cable; reciprocating cable-actuating means for imparting vertical reciprocating motion to a portion of the cable; a cable-clamping brake supported by the drill frame and engageable with the cable for braking a second portion of said cable, intermediate the winch and the reciprocated portion of the cable, against motion relative to the drill frame; brake-setting means connected to the brake and the frame for normally setting the brake; and means actuated in response to position of the cableactuating means for automatically unsetting the brake when the cable-actuating means reaches a position in advance of its normal reversal position from a tool-lowering to a tool-raising stroke and thereafter holding said brake unset during a predetermined portion of its cycle.

References Cited in the file of this patent UNITED STATES PATENTS

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