US2666244A - Drilling hook bill safety latch - Google Patents

Description

J. T. CARMICHAEL DRILLING HOOK BILL-SAFETY LATCH :s Sheets-Sheet 1 Jan. 19, 1954 Filed Dec. 10, 1952 INVENTOR" J. T. CARMICHAEL Jan. 19, 1954 J. T. CARMICHAEL 2,666,244

DRILLING HOOK BILL SAFETY LATCH Filed Dec. 10, 1952 3 Sheets-Sheet 2 bil ATTORNEY 1954 J. T. CARMICHAEL DRILLING HOOK BILL SAFETY LATCH 3 Sheets-Sheet 3 Filed Dec. 10, 1952 INVENTOR 1T CARMICHAEL ATTORNEY Patented Jan. 19, 1954 DRILLING:v HOOK BILL SAFETY LATCH James T. Carmichael, Shreveport, La., assignor to The Brewster Company, Shreveport, La.

Application December 10, 1952, Serial N 0. 325,152

Claims.

This invention relates to a drilling hook'bill safety latch and has for an object to provide an improved safety latch locking mechanism that will prevent the latch arm of the drillhook bill from being jarred open accidently, irrespective "of the direction in which the, jarring force may be exerted, yet wherein the latch arm can be readily opened'by application of manual force to receive or release a bail therein, and when 'th'ebail is received therein, the weight .of the 'bail'and the supported'parts may operate to automatically close the latch arm, and wherein the closing action ofthe latch arm will automatically"retract the latch bolt to permit the latch arm to move to closed position and then permit the latch bolt to extend to the latching position, and then be locked in such latching position by the improved mechanism of this invention.

I Still a further object of this invention is to provide an improved latch bolt and latch bolt locking mechanism for the latching arm on the bill of a drill hook, whichis incapable of being accidentlybpened, yet may be readily opened by application of manual force, and which will permit the latch arm to be automatically closed by the weight of the bail when in proper position in the notch-within the body of the drill hook. Still a further object of' this invention is to provide a drill hook latch arm locking mechawherein a vertically slidable latch bolt therefore is held in locked extended position by means of one bell crank pivotally mounted for rotation in one circumferential direction about its pivot and operated in the releasing direction by a second bell crank mounted thereabove which is pivotally mounted for rotation in an opposite circumferential direction, whereby the effect of any jarring motion tending to rotate .tlie releasing bell crank is counteracted by the tendency of the locking bell crank to rotate in 'the opposite direction.

Still a further object of this invention is to provide a safety latch bolt slidably mounted in the latch arm pivoted on the bill of a drill hook,

wherein the" latch bolt is urged toward extended .locking position by means of a spring biased at one end against its'bottom and biased at its other end against one arm of a bell crankbolt lock tending to rotate the bell crank bolt lock to bring its other arm into abutting relation with a shoulder provided on the latch bolt, and a trigger lever bell crank pivoted on the latch bolt having one arm in abutting relation with the shoulder-abutting crank arm of the latch bolt crank arm and having its other arm providing a drill hook bill in such relation to the spring biased crank arm of the latch bolt lock bell crank that the lip is normally in the opening path of said spring biased arm unless the bolt lock bell crank has been pivoted to unlocking position to permit the latch arm to be opened, and then when the latch arm is being automatically closed by the weight of the bail thereon, and then the bottom of the spring biased crank belt arm cams on the lip cam of the bill to permit the slidable latch bolt to retract as the latch arm is being closed until it is in closed position, and then to release to extended bolting position and be locked in such extended bolting position by the latch bolt lock bell crank lever.

Although the term drilling hook is used throughout, it will be understood that the term drilling hook refers to the type of hook that is ordinarily employed in rotary drilling for supporting the drill pipe, and is also used for raising and lowering casings in the operation of connecting new sections of casing to the casing in the well, and then lowering the casing so as to enclose that portion of the well that has been drilled, and the term drilling hook is therefore intended to generically cover any possible and customary use of such a hook.

With the foregoing and other objects in view, this invention comprises the combination, construction and arrangement of parts hereinafter set forth, claimed and disclosed in the accompanying drawings, wherein:

Fig. 1 is a side elevational view of a drilling hookand supporting sheave, the latch arm of the drilling hook having this invention installed therein.

Fig.2 is a front elevational view looking at the left side of. Fig. 1.

Fig.v 3 is an enlarged fragmentary view of the drill hook body, bill, and latch arm thereon with the safety locking mechanism of this invention ,shownpartly in section therein, with the latch arm in closed and locked position.

Fig. 4 is a similar partly sectional View of the latch arm and latchingmechanism on a slightly larger scale in fully opened position.

it tion with the latching end of the latch bolt in camming position about to cam the bolt to retracted position so that it may pass by the looking protrusion of the hook body.

There is shown at II) a drilling, rotary or casing hook sheave block having the usual sheaves therein accessible through the cable openings H, with its usual depending structure l2 and an internal" shank, not shown, secured by means of the swivel pin l4 to the drilling hook body |5. This drilling hook body l5 may be provided with the customaly eleyat or link supporting arms l6 and link latches as usual.

The drilling hook body I5 is provided-with an integrally formed bill l8 having .a latch arm,

pivotedly mounted thereon by the pivot pin 2| for closing the hook notch 22. Thedetails latch arm 20 between latch arm protrusi'ons 2 am on one side, and a latch arm pridtru'sion26, and a' roller 2 '|v on a pin 28 on th eother side; The latching end 3|! of the latch belt is provided with a's'urface 3| which bears against the roller 2'! and a recessed step 32 which-"abuts against the'roller2'l to limit the sliding move ent or the latch bolt 23, in the eitending orlatching direction. A bevelled cam surface33 is provided on the drilling hook body side of the latch bolt end 30, and is arr'alrigedfto cam aga'irist a correspondingly bevelled camsurface 34'onthe outer side'of a locking'protrusion 35rintegrally formed on the drillhookbody |5 at the top'endofthdnotch. 22 ,fp'rotrusion' 35 being also prQYidfifi With a keeper notch 35 having a keeper tongi fi 31- the keeper-notch 36, receiving thef'latch erid13| when in'latched position wi h theendof the bearing e i 'ef I. e eei' e ar n e eiee h keeper toe' 31.

So long as the latch bolt 23, has its end,30

extendeddnto the keeper'notch 35, the latch arm 20. "will remain inlatched position; The

latch arm' 20 is provided with an extending eye 38, which as shownj'in Figs] 3 and 6. ezrtends into a recess 4|l ,integral1y"formed in the body lfiabove the protrusion 35.:

In order to ,l ck thflat ch .bolt 23in th egg tended or lat hing position, a bell crank latch bolt locking lever M is provided pivoted on a pin at the bell crank angle within the latch a 0 below th eteh el. weat er n bell crank arm '43 extending substantially horizontally to "below" the latch bolt 23. 'A'yieldable spring 4 i'has'one end biased against the bottomend of latch bolt 23 urgihgthe latch bolt 23 toward the extended 'or latched position, and has its other end biased against the top of the horizontally extending bell crank arm 43, thus, tending to rotate the bell crank bolt lock arm 4| in counter-clockwise direction, as viewed in Figs. 3 to 6 inclusive. The vertically extending bell crank arm '46. on bell crank 4| extends alongside the latch bolt 23 above its "bottom'end 45;. and is urged by the spring 44 to t tiene Fi s." 1 d. 3k Hewe e 4 a locking position abutting against the bottom of a shoulder 41 formed on the latch bolt 23 and spaced above its bottom end 45, as shown in Fig. 3.

As will be apparent, the biasing force of spring 44 serves both to extend the latch bolt 23 and rotate the bell crank 44 so that the end of the bell crank arm {56 is heldin this abutting and locking relation against the shoulder 41 of the latch bolt 23. Before the latch bolt 23 can be retracted to permit the latch arm to open the notch 22 the bell crank arm 46 of bell crank 4| must be moved to a non-abutting position in relation to the latch bolt shoulder 41-, this position ofbell crank M being shown in Fig. 5. This action is provided by means of a second bell crank trigger lever 59, which is pivoted, not to ,the latch arm 2|], but within the latch bolt 23 and has a bell crank toe end 52 arranged to abut against and push the bolt lock bell crank arm' 65 out from under the latch bolt shculider e1 when the bell crank is rotated in a coinjiterclockwise directiOnQa's is viewed in Figs. '3 to 6 inclusive. trigger arm 53 is provided by the other bell crank arm of thebell crank Mandi is arranged to be moved in a downward direction as by a hooked rod .54. temporarily extended thereove'r and pulled downwardlmas in ili'igs l and 3, by manual force. Application of manual force in a downward direction on the trigger arm 53 of trigger bellv crank 55 thusefi rst locks the latch bolt 23'and then further appl a,- tion of manual force the same downward direction retracts the latch bolt, 23 downw rdly against its biasing 'spring'd l. V

The bill It is provided at its end with alip 55 having'a camming surface 56 on the back thereof. The lip 55. cooperates an abutmenu 51 in the latch arm '20 to limit the open.- irig movement of latch arm'ZQ, a sfsl rovszri 4. When the latch arm Z Q is, in notcnclgsin position, as shown in Fig 3., thefspringfbiasing l i eer 1% is n e e iien eebut agains h l e 5 an Pr e t th e hineei he a ch arm as shown in. Rig. 3, in" additiontothe locking effect provided by its'other: bell crank arm 46.. 'I-Ioweven'movement"oithe bell. crank lock 4| from the position shown in Fig. 3 un: der manual force' on rod 5 4 .moves the bell nk 4|" to the position shown'in Fig; 6 rela the latch arm, and raises'the spring lasing bell crank arm '4 3i. clear or the end of. lip 55, thus permitting 7 it to'ride thereover to allow the latch arm 43. to move toiits eigtren eadvanceposition, with abutment. '51 v in Contact against lip 55,.a s showninel ig. 4,1,, h in e i ii ln i he ai ing the drilling ol rotary mechanism may be mo e rom ne ig 1 may e ec iv d in notch 22. The arrow Wshows the po si on that the bailisv placed and as ill be seen the ead ef the ail. w i f ee ee' ie lte' the l t h arm pivot n t us endin e ause he. latch arm t e e r m. e eiii eef..-F .e- Me. the position of. Fig. Sfand Fig. 'fiback to the closed as manual forceon rod, .isrelieved, lock 1. W a en ie' th e ne d P-eeii en hew. i Figs. 3 to 6, so longas the extreme. endhh of later; e t 23; is. c lear 'of th i otensi rieeef 3;: e? h eep r ne 'ete vpr iiei t'wbdht it ji he e lse iie iiiea w- 1' 1 3x 2 any extended position sh wn infiigsdi}. 5. and 6.

hev fully e en beet es te e. .i .J h

" biasing spring 44 has again moved the bell crank "lock counter-clockwise and brought its locking end 46 in shoulder abutting position against shoulder 41 of latch bolt 23, thus locking the bolt 23 in extended position. However, as the weight W of the bail is placed on the end of latch arm within notch 22,'its eccentric position relative to the pivot pin 2| tends to rotate the latch arm 20 toward closing position. 'As this latch arm-2fl rotates from the position of Fig. 4 through the J positions shown in Figs. 5 and 6 to the position shown in Fig. 3, the bottom surface 58 of the .spring. biasing bell crank arm 43 cams-against thecam surface 56 on back of lip 55; as the latch arm 20 moves from the position shown in Fig. 4 to the position shownin Fig. 5, thus, rotating bell crank 4| clockwise to non-locking position 3 and continuing to hold it in nonelocking position until the cam surface. 33 on the latching end 34 .of latch bolt 23 camsagainst the cam surface 34 ,of protrusion 35, thus, moving the latch bolt 23 temporarily to retracted position until the latch arm is in fully closed position, whereupon the spring 44 biased against the bottonr45of latch bolt -23 urges and moves it into extended locking position with the bearing surface 3| thereof behind the protrusion surface 31, thus, permitting the latch arm 23 to automatically retract and then automatically advance to latching position to be held locked in such latching position by the bell crank lock 4| as the load W of the bail automatically pivots the latch arm 2!] from .fully open position of Fig. 4 through the intermediate positions of Figs. 5 and 6 to the fully closed and locked position of Fig. 3. s

As a result of this construction, any jarring force in any direction cannot accidently retract the latch bolt 23 or accidently unlock the latch arm 20. Any force tending to rotate trigger bell crank 50 in counter-clockwise direction and neoessarily also tending to retract the latch bolt 23 will increase the biasing force on the spring 44, and thus, on the spring biasing arm 43, to thus rotate the bell crank lock 4| in counter-clockwise direction about its pivot, which is below the pivot of the bell crank 50, and thus, hold the locking crank arm 46 more securely in abutting position i against the latch bolt shoulder 41, thus, preventing any accidental unlatching movement of latch bolt 23. t

However, as explained above, application of manual force on the trigger arm 53 first unlocks the latch bolt 23, and then retracts latch bolt 23 to the unlatched position, and then pivots the latch arm 20 to the open position of Fig. 4. Then, placing the bail of the drilling or rotary 1 mechanism within notch 22 as above described pivots the latch arm 20 to notch closing posithe bell crank lock arm 46 under shoulder 4'! to.

hold the latch bolt 23 locked in latched position, safe against accidental opening.

While the device'has been shownand the structure described in detail, it is obvious that this invention is not to be considered as being limited to the exact form disclosed, and that changes in detail and construction may be made therein within the scope of what is claimed,

without departing from the spirit of this inven- ---tion.'

Having thus set forth and disclosed the nature of this invention, what is claimed'is:

1. In a safety drilling hook having a body with a forwardly extending bill forming a bail-receiving notch and a latch arm pivoted to said bill and adapted to'close the entrance to said notch, a safety latch bolt slidably mounted on said latch arm for movement in a substantially vertical plane to engage in akeeper notch in the hook body, and having its upper latching end adapted to'engage a cam surface on the outside of the member forming a wall of said keeper notch in camming relation thereto to retract said bolt upon closing movement of said latch arm, a spring yieldably biased at its upper end against the lower end of said latch bolt, a latch bolt lock comprising a bell crank lever pivotally mounted on said latch arm at its angle'with one crank arm providing a biasing support for the lower end of said spring, thereby biasing its other crank arm against one side of said latch bolt, a shoulder on said latch bolt spaced from its said lower end, said latter crank arm having its end moved to and held in abutting relation with the portion of the'latch bolt under said shoulder by said biasing spring when said latch bolt is extended, a bell crank trigger lever pivoted on said latch'bolt, a bell crank toe end on said bell crank trigger lever arranged to push said latter crank arm below said shoulder against its biasing force away from abutting relation with said latch bolt below said shoulder, and a trigger arm at the other end of said bell crank trigger lever operativeunder manual force to pivot said bell crank trigger lever to thus disengage said latter bolt lock crank arm from below said shoulder, then slidably retract said latch bolt from engagement' with said keeper notch in said hook body, and then pivot said latch arm to open the entrance to said bail-receiving notch.

2. In the device defined in'claim l, a roller journaled in said latch arm, a surface on said latch bolt bearing against said roller to guide said roller in extendingand retracting movement, and a shoulder on said latch bolt at the end of said a safety latch bolt slidably mounted on said latch arm for movement in a substantially vertical plane to engage in a keeper notch'in the hook body, and having its upper latching end adapted "to engage a cam surface on the outside of the member forming a wall of said keeper notch in camming relation thereto to retract said bolt upon closing movement of said latch arm, a spring yieldably biased at its upper end against the lower end of said latch bolt, a latch bolt lock comprising a bell crank lever pivotally mounted on said latch arm at its angle with one crank arm providing a biasing support for the lower end of said spring, thereby biasing its other crank arm against one side'of said latch bolt, a shoulder on said latch bolt spaced from its said lower end, said latter crank arm having its end moved to and held in abutting relation with the portion of amaze abutting;:rel-ati'on with said-latch bolt below-said arm to opentheentranceito said bailereceiving notch, anda lip having; its inner. side extending from said. bill. into the opening path. ot; said spring-biasing. bolt lock crank armonly when said other boltlock crank arm is in bolt-abuttingPQsition, said spring-:biasing crank .arm moving clear ofsaid dip, when said bolt-abutting-crank arm is pivoted to non-abutting; position, I

4. Ina safety dr-illing hook having a body with a forwardly extending bill formingabail-receivingcnotch and alatcharm pivotedto said bill and adaptedto closetheentrance tosaid notch,

a safety latch bolt slidably mounted on said latch arm for movement ina substantially, vertical plane to. engage in a keeper. notch inthehook body, and having its upper latching end adapted tonengage acam; surface on the, outside of the member formingarwallof saidkeeper notchin camm-ing relation; thereto-to retract. said bolt upon closing movement of said latch arm, aspring yieldably biased at its upper end against the lower end of said: latch-bolt, .a lat-ch bolt lock'comprising a-bellcrank leverzpivotallymounted on said latch arm at* its angle: with one crank arm providing abiasingsupport for the lower end, of said spring, therebybiasing. its other crank arm i againstoneside of-saidf latch bolt, ashoulder on saidlatch boltspaced from its said lower end, said latter cranlc arm-.having-its endmovectto and held in abuttingrelation with the portion of the latch bolt undersaid shoulder by; said biasing spring when said i latch boltis extended, a. bell crank trigger lever pivoted on said latch bolt, a bell crank-toeend on. said bell crank trigger lever arranged to push. said latter crank arm below said shoulder against its biasing force away from abutting; relation with said latch bolt below said shoulder, a trigger arm at the other end of said bell crank trigger lever operative under manual force to pivot said bell crank trigger lever to thus disengage said latter bolt lock crank arm from below said-shoulder, then slidably retract said latch bolt from engagement with said keeper notch in said hook body, and then pivot said latch armito opentheentrance to said, bail-receiving notch,- a lip having its inner-side extending from said billzinto the opening path of said springbiasing bolt lock crank arm only when said other;

bolt lock crank arm is in bolt-abutting position, said spring-biasing crank arm moving clear of said; lip when said bolt-abutting-crank arm is pivotedto non-abutting position, and a. cam surface provided on-the outer side of said lip adapted. to, cam-against the bottom end of said springbiasingcrankarm when said latch arm is moved innotch-closing direction to pivot said shoulderblockingcrank arm to non-blocking position and permit said. keeper-notch cam surface to, move.

adapted to closethe. entrance to said notch, a-

safety latch bolt ,slidably mounted on said latch arm for movement in a substantially vertical planeto engage in a keeper notch. in the hook body, and having its upper latching end, adapted viding a biasing support for the lower endof said spring, thereby biasing its; other crank. arm against'one side of said latch bolt, a shoulder on said latch; bolt spacediromits said-lower end, said latter crank arm having its end moved. to and held in abutting relation with the portion of the latch bolt under said1shoulder by said biasing spring: when said latchbolt is extendedsaid latter crank armbeing thereby adapted-:toaact as a stop forsaidshoulder to prevent downward movement of said latch .bolt against the force of said biasing spring, a'bell crank trigger levercomprising a-second leverpivoted for initial rotation in the direction opposite from that otsaid first bell crank lever at its angle on said latch bolt below said shoulder, a bell crank toe'end on said bell crank trigger lever arranged to push said latter crank arm below said shoulder against its biasing force away from abutting relation with said latch bolt-below said'shoulder, and a trigger arm at the other end of said bel-l'crank trigger lever operative under manual force to pivot said bell crank trigger leverto-thu'sdisengage said latter bolt lock crank arm'from'below said shoulder, then slidablyretract said latch bolt from engagement-with saidkeepernotch in said hook body, and then pivotsaid latch arm .to open the entrance to said bail receivingnotch.

6. In a safety drilling hook having a body with a forwardly extending bill forming a bail-receiving notch anda latch arm pivoted tosaid bill and adapted to close the entrance to said notch, a safety latch .bolt slidably mounted. on said latch arm for. movement in a. substantially vertical plane to engage in akeeper notch inthe hook body, and having its upper latching end adapted toengage a. cam surface on the outside of the member formingawall of-said keeper notch in cammingi relation thereto to. retractv said bolt upon closing movement of said latch arm, a spring yieldably biased at its upperiend againstthe lower end of said latch bolt, ailatch boltlock comprising a bell crank lever pivotally mounted on said latch arm at its angle for. initialrotation. in one circumferential .direction with one crank arm providing a biasing support for the lower end of said spring, thereby biasing; its other crank; arm against: one side-of saicl latch bolt, a shoulder on said latch boltspaced from;its-.said lower end, said latter crank arm havingits end. moved toand held in abutting relation with the portion of the latch bolt under said shoulder. by said biasing spring when said latch bolt is extended, said latter crank arm being thereby. adapted to act as a stop for said shoulder to prevent downward movement of saidlatchbolt againstthe forceof said biasing" spring, a, bell crank trigger lever comprising a second'lever'pivoted for initial rotation in I the. direction opposite from. that of said first bell crank. lever atjitsangle on said latch bolt below said. shoulder, abell cranktoe. end. on said'bell crahk t'rigger lever arranged. topush said latter crank arm. below said shoulder against itsbiasing forceaw'ayirom abutting relation with said latch bolt below said shoulder, a triggeriarm at the other end of said bell crank trigger lever operative under manual force to pivot said bell crank trigger lever to thus disengage said latter bolt lock crank arm from below said shoulder, then slidably retract said latch bolt fromengagcment with said keeper notch in said hook body, and then pivot said latch arm to open the entrance to said bail-receiving notch, and a lip having its inner side extending from said bill into the opening path of said spring-biasing bolt look crank arm only when said other bolt lock crank arm is in bolt-abutting position, said springbiasing crank arm moving clear of said lip when said bolt-abutting crank arm is pivoted to nonabuttin position.

7. In a safety drilling hook having a body with a forwardly extending bill forming a bail-receiving notch and a latch arm pivoted to said bill and adapted to close the entrance to said notch, a safety latch bolt slidably mounted on said latch arm for movement in a substantially vertical plane to engage in a keeper notch in the hook body, and having its upper latching end adapted to engage a cam surface on the outside of the member forming a wall of said keeper notch in camming relation thereto to retract said bolt upon closing movement of said latch arm, a spring yieldably biased at its upper end against the lower end of said latch bolt, a latch bolt lock comprising a bell crank lever pivotally mounted on said latch arm at its angle for initial rotation in one circumferential direction with one crank arm providing a biasing support for the lower end of said spring, thereby biasing its other crank arm against one side of said latch bolt, a shoulder on said latch bolt spaced from its said lower end, said latter crank arm having its end moved to and held in abutting relation with the portion of the latch bolt under said shoulder by said biasing spring when said latch bolt is extended, said latter crank arm being thereby adapted to act as a stop for said shoulder to prevent downward movement of said latch bolt against the force of said biasing spring, a bell crank trigger lever comprising a second lever pivoted for initial rotation in the direction opposite from that of said first bell crank lever at its angle on said latch bolt below said shoulder, a, bell crank toe end on said bell crank trigger lever arranged to push said latter crank arm below said shoulder against its biasing force away from abutting relation with said latch bolt below said shoulder, a trigger arm at the other end of said bell crank trigger lever operative under manual force to pivot said bell crank trigger lever to thus disengage said latter bolt lock crank arm from below said shoulder, then slidably retract said latch bolt from engagement with said keeper notch in said hook body, and then pivot said latch arm to open the entrance to said bail-receiving notch, a lip having its inner side extending from said bill into the opening path of said spring-biasing bolt lock crank arm only when said other bolt lock crank arm is in bolt-abutting position, said springbiasing crank arm moving clear of said lip when iii the bottom end of said spring-biasing crank arm when said latch arm is moved in notch closing direction to pivot said shoulder-blocking crank arm to non-blocking position and permit said keeper-notch cam surface to move said latch bolt in retracting direction, the inside of said wall member of said keeper notch permittingsaid latch bolt to be extended by said biasing spring into latching position in said keeper notch.

8. In a safety drilling hook having a body with forwardly extending bill forming a bail-receiving notch and a latch arm pivoted to said bill and adapted to close the entrance to said notch, a safety latch bolt slidably mounted on said latch arm for movement in a substantially vertical plane to engage in a keeper notch in the hook body When the hook is in normal use, and having its upper latching end adapted to engage a cam surface on the outside of the member forming a wall of said keeper notch in camming relation thereto to retract said bolt upon closing movement of said latch arm, spring means biased at its upper end against the lower end of said latch bolt, normally urging said latch bolt toward the extended latching position, a latch bolt lock comprising a bell crank lever pivotally mounted on said latch arm at its angle, said same spring means being biased at its bottom end against one arm of said latch bolt lock and urging the other arm of said latch bolt look toward locking position with said latch bolt, and latch bolt lock pivoting bell crank means, pivoted at its angle, having one arm manually operative in a substantially downward direction for first pivoting its other bell crank arm against said other bell crank arm of said latch bolt lock against its, biasing spring end in a direction toward unlocking position and then retracting said latch bolt and latch arm to the unlatched position.

9. A safety drill hook as defined in claim 8 in which the pivoted latch arm is provided with an inwardly extending finger adapted to extend into said notch and be engaged by a bail received in said notch to automatically close said latch arm, and a cammed lip on said bill extending into the path of said latch bolt pivoting means camming against the bottom of said other latch bolt lock arm for operating said latch bolt lock pivoting means toward unlocking position to permit said latch bolt to be retracted by a cam surface in its path on said hook body and then extend as said latch arm is automatically closed.

10. A safety drill hook as defined in claim 8 in which both said bell crank latch bolt lock and said bell crank latch bolt lock pivoting means are pivotally mounted one above the other for initial movement in opposite circumferential directions said bolt-abutting crank arm is pivoted to nonabutting position, and a cam surface provided on the outer side of said lip adapted to cam against each with a vertically extending arm in side-byside abutting contact, the horizontal bell crank arm of the latch bolt lock bell crank having said spring means biased thereon, the horizontal bell crank arm of the latch bolt lock pivoting means bell crank being the arm manually operative in a substantially downward direction.

JAMES T. CARMICHAEL.

No references cited.

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