US1817467A - Feed for well drilling tools - Google Patents

Description

Aug. 4, 1931. w. N. THOMPSON FEED FOR WELL DRILLING TooLs 2 sheets-sheen 1 Filed Nov. 3, 1930 Mis fQTfae/yf Aug. 4,'1931.' w. N. THOMPSON 1,817,467

FEED FR WELL DRILLING TOOLS Filed Nov. 3, 1930 2 sheets-shea 2 Patented Aug. 4, 1931 PATENT OFFICE WALTER N. THOMPSON, 0F HUNTINGTON BEACH, CALIFORNIA.

FEED FOR WELL DRILLING TOOLS Application led November 3, 1980. Serial No. 492,959.

This invention relates to a drilling control or feed and relates more particularly to an hydraulic feed for rotary well drilling tools.

With the ordinary or standard rotary method of well drilling, a drive is provided for rotating the drill pipe, and hoisting equipment is provided to handle the vertical movement of the drill pipe. It is common practice to rotate the drill pipe by a rotary`J of the drill with the formation becomes excessive, the driller operates the hoisting equipment to relieve the pressure of the drill on the formation. When drilling through certain types of formation, it has been found desirable to provide a control or feed for feeding the drill into the formation at a constant pressure. Mechanisms termed automatic feeds have been introduced to control the feed pressures and, in some instances, to correlate the rotary drive andthe vertical feed pressure.- Controls of this character are extremely complicated and expensive and cannot be applied to the standard types of rotary unit, but require the installation of eX- pensive special machinery at the derrick.

It is a general object of the invention to provide a simple, practical, and effective feed for rotary well drilling tools.

It is another object of the invention to pr0- vide an hydraulic feed for well tools that may be readily mounted on, and used in connection with, a standard or typical rotary unit.

It is another object of the invention to pro- .vide a feed for drillingy tools that is adapted to be mounted on a common rotary unit, and that is adapted to effectively control the vertical feeding of the drilling tools by engaging or carrying the usual kelly or drill stem.

It is another obje'ct of the invention to p rovide a feed for drilling tools that is partltcularly slmple and easy to control or opera e.

It is another object of the invention to provide an hydraulic feed for drilling tools that may be automatically released from the drilling stem, so that it may be handled by the hoisting equlpment in the derrick. Y

It .1s a further object of the invention to provide a feed for rotary well drilling tools that embodies but few sturdy parts, and that 1s simple and inexpensive of manufacture.

The various other objects and features of my invention will be best and more fully understood from the following detailed description of a typical form and application of the invention, throughout which description reference is had to the accompanying drawings, in which:

Fig. 1 is a side elevation of the control pro- 65 vided by the presentA invention, illustrating it mounted on a ty ical rotary unit and in engagement with a rill stem carried by typical hoisting equipment. Fig. 2 is a top or plan View of the control, being a view taken as indicated by line 2-2 on Fig. 1. Fig. 3 is an enlarged vertical detail sectional view of the control, illustrating the device in an operative or intermediate position. Fig. 4 is a view similar to Fig. 3, illustrating 75 the cylinder at thevtop of its stroke where the slips are released from the kelly. Fig. 5 is an enlarged transverse detailed sectional view taken as indicated by line 5 5 on Fig. 3. Fig. 6 is an enlarged side elevation of the 80 upper portion of the feed, being a view taken as indicated by line 6-6 on Fig. 3, and Fig.

7 is an enlarged transverse detailed sectional view taken as indicated by line 7-7 on Fig. 3.

The drilling tool feed or control provided by the present invention is intended to be used in connection with standard or typical rota well drilling equipment. Throughout the following detailed disclosure of the invention, it will be described in connection with a typical rotalc?7 unit and as en aging a common kelly or r the usual hoisting equipment. e invention is not primarily concerned with the type of drilling e uipment with which the feed is used, and t e invention is not to be considered as restricted to the particular well drilling equipment illustrated in the drawings.

The rotary unit illustrated in the drawings includes skids 10, a rotary table 11 projecting above the skids 10, a shaft 12 mounted on the skids through suitable bearings 13 and carrying a bevel gear 14 for rotating the table 11. The table 11 may be a typical or common rotary table for carrying slips, kelly bushings, etc. Throughout the following disclosure, the rotary table 11 will be considered as carrying a kelly bushing for engaging and driving thekelly 15. The kelly 15 and drilling string carried thereby is adapted to be suspended in the derrickfrom lines or cables 16 carrying a travelling block 17. The block 17 is provided with a hook 18 for carrying a swivel 19. The swivel 19 is applied to the upper end of the kelly 15 and is provided to discharge circulating fluid into the kelly. lThe kelly and drilling string are adapted to be rotated or driven by the rotary table, and may be operated vertically by the travelling block 17 and the other hoisting equipment of the derrick.

The feed provided by the invention includes, generally, a base plate 2O adapted to be mounted on the rotary table 11, a stationlary body or piston 21 mounted on the base plate 20, a cylinder 22 slidablyl mounted on theA piston 21 and operable by fluid under pressure, slips-23 carried by the cylinder 22 tol engage the kelly 15 for supporting the ,drilling tools, and means 24 for automatically position, where its central opening 25 is in register with the opening 26 in the table and the opening in the kelly bushing (not shown).

n The opening 25 is sufficiently large to pass the various sizes of drill stems or kellies and the couplings of the drilling strings with considerable clearance. The base plate 20 is connected with the table 11 to rotate therewith. In the simple form of the invention illustrated in the. drawings, spaced lugs 27 project downwardly from the lower side of the plate 20 to fit into suitable openings in the upper side ofthe rotary table 11. With this connection, the plate 20 may be easily and quickly mounted on and dismounted from the table 11. An upwardly projecting annular ill stem norma ly carried byflange 28 is provided at the perimeter of -the plate 20.

The body or piston 21 is supported on the I base plate 20 and projects upwardly therefrom. The piston 21 is'an elongated tubular member having an enlarged lower end, or flange, 29. The flange, orenlargement, 29 fits into, or is surrounded by, the fiange 28. The enlargement 29 is vmounted on the base plate 2O through a suitable bearing. In the particular case illustrated, three rows or series of balls 30 are arranged in races formed between the base plate 20 and the lower side of theflange 29. An upwardly projecting flange 31 may be provided on the base plate 20 around the opening 25 to fit into a groove in the piston. The piston may be held against vertical displacement from the base plate 20 by an annular plate 32 mounted on the flange 28 and engaging or overlapping the upper side of the enlargement 29. `The piston 21 is lmounted on the base plate 20, so that its central longitudinal n opening 33 is in registenwith the opening 25 of the plate. In accordance with the invention, the piston 21 is held against rotation. The piston may be held stationary in any suitable maner. In the simple form of the invention illustrated in the drawings, an arm 34 is mounted on the upper side of the enlargement 28 and projects outwardly beyond the plate`20. The ar-m 34 is adapted to engage a'post 35 projecting upwardly from the rotary unit to old the piston 21 against rotation.

The piston 21 is comparatively long, and

projects upwardly some distance from the enlargement 29. An enlargement or head 36 is provided on the upper end of the piston 21. The head 36 is circular or annular.

The cylinder 22 is slidably mounted on the piston 21 and is operable upwardly by fluid under pressure and downwardly by the weight ofthe string of tools supported on the cylinder through the engagement of the slips 23 V`with the kelly 15. The cylinder 22 is an elongated member having a central longitudinal opening 37 freely passing the kelly 15. The cylinder 22 surrounds or encases the u per portion of the piston 21, and is provi ed' with an annulus, or annular opening, 38 for slidably passing the head 36. The cylinder opening 38 extends upwardly into the cylinder from its lower end, and is comparatively long or deep so that the cylinder has a long stroke. A suitable packing or sealing means is provided on the head 36 to seal with the walls of the cylinder' opening^38. In the particular case illustrated, two rlngs of packing 39 are clamped on the head 36 between plates 40. The packing rings 39 are operable to seal with the inner andouter walls of the, cylinder opening 38. Means isprovided for holding the cylinder 22 against rotation on the piston 21. A. suitable ke connection 41 may be provided between tie inner wallsof the o icning 38 and the Walls of the opening 33 o the piston.

Fluid under pressure, say, oil, may be discharged into the upper cncl of the cylinder opening 38 for operating the cylinder 22 upwardly. In the drawings, I have illustrated a Vflexible hose or conduit 42 connected with a pipe or nipple 43, communicating with the upper end of the cylinderI opening 38.` A suitable 4valve 44 may be provided at the connection of the flexible conduit 42 with the nipple 43. Fluid under pressure -may be applied to the opening. 38 under pressure from a suitable remote source of supply and by suitable pressure developing means. The flexible conduit 42 may extend to a convenient point in the derrick where a valve may be provided for controlling the supply and discharge of fluid to and from the cylinder opening 38.

The slips 23 are mounted in the upper end of the cylinder 22 to engage the kelly 15 for supporting the drilling tools. A set or vplurality of s ips are rotatably mounted in the upper end part of the cylinder. In the drawings, I have shown four like slips 23, one for engaging each face of the kelly. It is to be understood that any suitable type of slips may be employed for co-operating with drill stems or kellys of various characters. Teeth or gripping parts are rovided on the inner parts of the slips 23 or gripping the kelly 15. The slips 23 are removably carried by a ring or bushing 45. The i bushing 45 is annular in form and is rotatably carried in a recess 46 in the upper end of the cylinder 22. The bushing 45 may be rotatably supported by a suitable roller bear- 'ing 47 in the bottom of the recess 46. The

walls of the opening 48in the bushing diverge upwardly and outwardly, and the outer sides of the slips 23 are shaped to slidably fit the walls of the opening. Suitable dovetailed connections 49 ma /be provided between the outer sides of the slips 23 and walls' of the opening 48. The slips 23 are forced into effective gripping engagement with the kelly 15 upon downward movement in the opening '48, and are released from the kelly upon movementupwardly in the opening.

It will be apparent how the kelly 15, driven by the rotary table 11, may be supported on the. cylinder 22 by the slips 23 and bushing 45. The kelly and drilling tools may be fed or allowed to feed downwardly by permitting the fluid in the opening 38 to discharge through the conduit 42 at a desired rate. The rate of ldownward movement of the cylinder and kelly 15 may be readily controlled by valve means in connection with the conduit 42. The hoisting mechanism in the derrick may be` employed to carry a portion of the weight of the drilling tools, and the strain taken by the hoisting mechanism may be reconduit 42 to'cause the'bit to be fed into the formation at any desired speed. When the cylinder 22 reaches the lower end of its stroke, Huid under pressure may. be discharged into the cylinder opening 38 to return the cylinder to an up position. The slips 23 ma be left in engagement with the kelly 15 w en the cylinder 22 is returned to e up position so that the strin and the dri-lling tool is raised. This is deslrable, as 1t 1 s not good practice to permit the entire weiglht'of the drilling strin to be supported on t e bottom of the well )ore through the drilling tool. Further, it may be desirable to raise the drilling tools to free them from cuttings, etc., in the bore.

The means 24 acts to automatically release the slips 23 from the drill stem or kelly 15 upon the cylinder 22 reaching the upper end of its stroke to permit the drilling string to be lowered into the bore by the hoisting mechanism to bring the drilling tool into engagement with the bottom of the bore or to a point adjacent the bottom of the well bore. The means 24 is in the nature of an automatic cam means and includes an upper ring 50 mounted above the bushing 45. The central opening in the ring 50 is in register with the upper end of the tapered opening 48. A downwardly projecting annular flange 51 is provided at the periphery of the ring 50. The fiange 51 extends into an annular groove 52 inthe upper end of the cylinder 22. A cam ring 53 is rotatably mounted in the groove 52 below the flange 51. The upper sidelof the cam ring 53 and the lower side of the flange 51 are in the form of co-operating 'cam faces, operable to cause upward movement of the upper ring 50 upon rotation lor partial rotation of the cam ring 53 relative' lated to the rate of flow of fluid through the i to the upper ring. The co-operation between the rings 50 and 53 retains the upper ring 50 spaced above the topof the b-ushing 45. The upper ring 50 is held against rotation by pins or lugs 54 projecting outwardly from the flange 51 and -slidably fitting notches 55 in the upper end of the cylinder 422. Upward movement of the ring 50 causes disengagement of the slips 23 from the drill stem or kelly 15. Each of. the slips 23 is provided with an upwardly-projecting arm 55. A lug or finger 56 projects outwardly from the upper end of each of the arms 5.5

to engage over the upper side of the ring 50. A suitable anti-friction bearing ring 57 may be provided in the upper side of the rin 50 to engage the fingers 56.

The cam ring 53 is automatically rotated upon the cylinder 22 reaching the upper end of its stroke. The means for rotating or partially rotating-'the cam ring 53 when the cylinder approaches the upper endof its stroke is in the nature, of an automatic cam means, and includes a plate 60 slidably mounted on the outer side of the cylinder v- 61 may be screw-threaded into an aienmg in the ring 53 so that the pin is re ly removable. The pin 61 extends outwardly throu h the oblique or angularly disposed Acam s ot 62 in the plate 60. The pin 61 extends into the lower end of the cam slot 62 -when the slips 23 are in the operating position on the kelly 15.

The operating rod 63 projects downwardly from the lower end of the late 60 and extends to a point below the ower end of the cylinder 22. 'Ihe rod 63 may be uided by guides '66 on the side of thegf 'nder 22. The lower end portion of the r 63 is bent to have an upwardly projecting arm 67. The arm 67 may normally project upwardly into the lower end of the ylmder opening 38. The arm 67 is adapte to engage the lower side of the piston head 36 upon the cylinder 22 approaching the upper end of its stroke. It w1ll be apparent how. engagement of the arm 67 with the head 36 will cause downward movement of the rod 63 and the plate 60 relative to the cylinder 22. Downward movement of the late 60 causes cooperation between the pm 61 and the cam slot 62 so that the cam ring 543 is partially rotated. Partial rotation ofthe cam ring '53 upon downward movement of the plate 60 causes the co-operation between the cam faces of the rings 50 and 53 to raise the ring 50 so that the slips 23 are shifted upwardly out of engagement with the kelly 15. The

:lower end of the rod 63 and arm 67 are inaposition where they may be readily engaged and operated by a driller at the rotaryC unit so that the slips may released from the kelly at will. l

The present invention provides means for automatically returning therod 63 and the plate 60 to a down position relative to-the cylinder 22 when the arm 67 is disengaged from the head 36. The means for automatlcally returning the various parts of the means 24 to their normal positions is in the nature of a spring means and includes a helical compression spring 70. 'The spring 70 surrounds the rod 63, and its upper end is carried by .or engages a pin 71 on the rod. The lower end of the spring engages a guide 66 upon downward movement of the rod relative to the cylinder so that it is compressed'. Upon -disengagement of the arm 67 from the head 36, the spring 70 automatically returns .the

rod andthe plate 60 to their positions, so

that theslips23 are returned to a position in en agement wlth the kelly 15.

e control or feed provided by the present inder to its up position, t e slips 23 may be held out of engagement with the kelly 15. The wei ht of the drilling string, or a portion oft e weight of the string, may be supported on the cylinder 22 by means ofthe slips 23. The drilling tools may then be driven or rotated by the rotary unit, and the downward feeding of the tools may be regulated by controlling the rate of discharge of fluid through the conduit 42 and the strain, if any, taken by the hoist means in the derrick. Upon the cylinder 22 reaching the lower end of its stroke,`thc rotation of the drilling tools may be stopped and iuid pressure may be discharged into the o nin 38 to return the cylinder to its up position. uring this upward movement of the cylinder 22, the slips 23 may be left in engagement with the kelly 15 so that the drilling tool is raised from the formation at the bottom of the bore. Upon the cylinder 22 reaching the upper end of its stroke, the hoist mechanism in the derrick may be set to suspend the drilling string. When the arm 67 strikes the head 36, the cam ring 53 is rotated by co-operation of the pin 61 in Jthe cam slot 62. Partial rotation of the cam ring 53 causes the upper ring 50 to be raised so that the slips 23 are lifted out of engagement with the kelly 15. The drilling tools ma then be lowered by the hoist means in the errickso that the drilling tool is brought into engagement with the formation at the bottom of the well bore, or to a position adjacent the bottom of the well bore. A small amount of fluid may then be discharged from the cylinder opening 38 so that the arm 67 is disengaged from the piston head 36.

Upon disengagement `of the arm 67 from the head 36, the spring 70 returns the plate 60 to an up position and causes the cam ring 53 to be rotated in a reverse direction. Upon return of the ring 53 to its normal position, the upper ring 50 is permitted .to lower so that -thelslips 23 are brought into gripping engagement with the kelly 15. The entire weight of ,the string, or part of the weight of the strin may be supported on the cylinder throu the slips 23, and the rotaryrtable 11 maye rotated to drive the kelly. Fluid may be dischar mit t e drilling tools to feed downwardly, and the rate .of downward feeding of the tools may be effectively controlled or governed by regulating the rate of discharge through the conduit. Y l It is to be noted that the resent invention provides a simple and practlcal feed for drllling tools. The devices may be easily mount# lo ed on a typical rotary unit and maybe used in connection with the standard equipment. The control includes but few simple, sturdy parts and is particularly easy to control and operate. Theparts are not subjected to rotatlonal strains, as the piston and cylinder are h eld stationary during operation. The slips 23 are supported by the bushing 45 which is mounted for rotation on the cylinder. The means for automatically releasing the slips 23 go is simple and positive in its operation. The means 24 ma be manually operated or controlled if deslred to release the slips.

Having described only a typical preferred fofrm of my invention, I do not Wish to limit g3 myself to the specific details set forth, but wish to reserve to myself any changes or variations that may appear to those skilled in the art or fall within the scope of the following claims.

Having described my invention, I claim:

1. A feed for well drilling tools, including a stationary piston, a cylinder slidable relative to the piston, and slips mounted on the cylinder for engaging a drilling tool. 2. A device for use in connection with a rotary table, and a drill stem driven thereby which includes a piston adapted to be mounted on the table, a cylinder having an opening slidably receiving the piston and an opening freely 1passing the drill stem, and a set of sli s on t e cylinder for releasably engaging t e drill stem.

3. A device for use in connection with a rotary table, and a drill stem driven thereby which includes a piston adapted to be mounted on the table, a cylinder having an opening slidably receiving the piston and an opening freely passing the drill stem, anda set of slips on the cylinder for releasably engaging the drill stem.

4.-. A device for use in connection with a rotary table, and a drill stem driven thereby which includes a piston adapted to be mounted on the table, a cylinder having an opening slidably receiving the piston and an opening freely passing the drill stem, means whereby iuid may be discharged from the last-mentioned opening, and 'a set of slips on the cylinder for releasably engaging the drill stem.

5. A device for use in connection with. a rotary table, and a drill stem driven thereby which includes a piston adapted to be mounted on the table, a cylinder having an opening slidably receiving the piston and an opening freely passing the drill stem, means vslowly from the' conduit 42 to pe'rwhereby fluid may be dischargedy from the last-mentioned opening. and discharged into the last-mentioned openin under pressure, and a set of sli on the cy yder for release4 ably engaging t e drill stem.

6. A feed or usein 'connection with a rotary table and a drill stem, including a bearing plate adapted to be mounted a plston mounted on the bearing plate, means for holding the piston against rotation, a cylmder having an opening assing the drill stem andan opening slida ly receiving the piston, and releasable means for supporting the drill stem' on the cylinder.

7. A feed for use in connection with a rotary table and a drill stem, including a bearing plate adapted to be mounted on the table, a piston mounted on the bearing plate, means for holding the piston against rotation, a cylinder having an opening passing the drill stem and an opening slida ly receiving the piston, slips-for engaging the drill stem, and means supporting. the slips on the cylinder for rotation.

8. A feed for use in connectionv with a rotary table and a drill vstem driven thereb which includesa piston mounted on the tab e having an opening passing the drill stem, a'

on the table,

piston,'means for discharging fluid from the chamber and for passing fluid under pressure into vthe chamber, a slip for engaging the drill stem, means for rotatablyv supporting the slip on the cylinder, and lmeans for disengaging the slip from the drill stem.

10. A feed for a drill stem driven by a rotary table, which includes a piston to be mounted on the rotary table, a cylinder having a chamber slidably receiving the piston, means for discharging fluid from the chamber and for passing iuid under pressure into the chamber, a slip for engaging the drill stem, means for rotatably supporting the slip on the cylinder, and means for automatically disengaging the slip from the drill stem upon the cylinder approaching the upper end of its stroke. v

11. A feed for a drill stem driven by a rotary table, which includes a piston adapted to be mounted on the rotary table, a cylinder having a chamber slidably receiving the piston, means for discharging fluid from the chamber and for passing fluid under pressure into the chamber, a slipvfor engaging the drill stem, means for rotatably supporting the slip Y on the A y l ing'the slip from the drill stem.

cylinder, and cam means for disengag- 1 2. A feed for a drill stem driven by a rotary table, which includes a piston adapted to be mounted on the rotary table, a cylinder f having a chamber slidably receiving the pis- 'ton, means for discharging fluid from the chamber and for passing fluid under pressurel into the chamber, a slip for engaging the drill stem supported on the cylinder, and means for Y disengaging the slip from the drill stem, inf

cluding a r1ng, an arm on the slip engageable by the ring, and a cam for operating the ring.`

13. A feed for a drillstem drivenby a rotary table, which includes a piston adapted jto be mounted on the rotary table, a cylinder having a chamber slidably receiving the pist0n, means for discharging fluid from the chamber and for passing fluid under pressure into the chamber, a slip for engaging the drill stem, means for rotatably supporting the slip on the cylinder, and means for disengaging the slip from the drill stem, including a ring, an arm on the slip engaging the ring, a cam operable to raise the ring, and means for operating the cam.

14. A feed for a drill stem driven by a rotary table, which includes a piston adapted to be mounted on the rot-ary table, a cylinder having a chamber slidably receiving the piston, means for discharging fluid from the chamber and for passing fluid .under pressure into the chamber, a slip for engaging the drill stem supported on the cylinder, and means for -disengaging the slip fromthe drill stem, including a ring carried on the cylinder for verticalmovement, an arm on the slip operable by the ring, a lower ring, the rings having co-operating cam faces for causing vertical movement ofthe first-mentioned ring upon operation of the lower ring, and means for operating the lower ring.

15. A feed for a drill stem driven by a rotary table, which includes a piston adapted to be mounted on the rotary table, a. cylinder the slip from the drill stem, including a ring t carried on the cylinder for vertical movement, an arm on the slip operable by the ring, a lower ring, the rings having co-operatin'g cam faces for causing vertical movement of the f first-mentioned ring upon operation of the lower ring, and means for o erating the lower ring, including a rod slida ly carried by the cylinder and engageable by the piston.

16. A feed for a drill steml driven by a rotary table, which includes a'piston adapted to be mounted on the rotary table, a cylinder A.having a chamber slidabl receiving the pis-v ton, lmeans for dischargmg fluid from thel chamber and for passin fluid under'pres'sure.

into the chamber, aslip or engaging the drill stem, means for mounting the slip on the cylinder so that it is operable into and out of supporting engagement withy the drill stem, and

means for automatically disengaging the slip from thedrill stem upon the cylinder approaching the end of its s'troke,'includin a for vertical movement, a cam for operating .ring in engagement with'the slip and carried the ring vertically, al slidable rod'engageable by the piston, and an operative connection be- `tween the cam and the rod.

17. A feed for a drillstem driven by a rotary table, which includes a piston adapted to be mounted on the rotary table, a cylinder having a chamber slidabl receiving the piston, means for dischargin fluid from the chamber and for passingflmd under pressure.

inder approaching the end of its stroke, 1n-

cluding a ring in engagement with the slip and carried for vertical movement, a camfor operating the ring vertically, a slidable rod' enga-geable by the piston, and an operative cam connection between the cam and the rod.

18.- A feed for a drill stem driven by a 'rotary table, which includes a piston adapted to be mounted on the rotary table, a cylinder having a chamber slidabl receiving the piston, means for dischargm fluid from the chamber and for passing uid'under'pressure into the chamber, a slip for engaging the drill stem, means for mounting the slip on the cylinder so that it is operable into and out of supporting engagement with the drill stem,

and means for automatically disengaging the slip from the drill stem upon the cylinder approaching the end of its stroke, including a ring in engagement with the-sli and carrled for vertical movement, a cam or operating the ring vertically, a slidable rod engageable by the piston, an operative connection between the cam and the rod, and means for returning the rod and cam to the unactuated positions lll upon disengagement ofthe rod from the pisi 19. A feed foradrillstem drivenby a rotary table, which includes a piston adapted to 'be mounted on the rotar table, a cylinder having a chamberslidab y receiving thepiston, means for discharging fluid from the chamber and for passing fluid under pressure into the chamber, a slip for engagmg the drill stem, means for mountin the slip on the cylinder so that it is opera le into and out of supporting engagement with the drill stem, and means for automatically disengaging the slip from the drill stem upon the cylinder approaching the end of its stroke, including va o of October, 1930.

WALTER N. THOMPSON.

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