US1783328A - Crown block - Google Patents

Description

Dec. 2, 1930 w. D. DAVIDSON CROWN BLOCK Filed Jan. 9, 1928 2 Sheets-Sheet 2 EA/T012. WILL/HM D. DH IDSON, B)

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Patented Dec. 2, 1930 BUNITEDISTATES PATENT OFFICE WILLIAM nInnvrnsolv, or Los A enLrls, onnrronnranssreivon 'IO EMSCO DERRICK & EQUIPMENT ooMrANY. 013 LOS ANGELES, CALIFORNIA, VA CORPORATION or GALI- roams oaowiv BLOCK Application filed, January 9, 1928. Serial'No/2 i5,5 90.

erected with the vertical axis thereof coinciding with the verticalaxis of the proposed well, In carrying out the drilling operation,

heavy tools and sections of tubing must be,

suspended within the derrick substantially on the vertical axisthereof so that these may be hoisted or lowered at will. To effect this, tackle is rigged up which includes a multiple sheave traveling block and a multiple sheave crown block, the latter being stationary and mounted upon the top of the derrick. A.

cable, which is wound around the sheaves of the blocks to complete this tackle, is connected to the drum of a draw Works whichis power operated so as to raiseor lower the traveling In the older s of crown blocks in general use, light hoisting within thederrick was accomplished by a cable wound around a sand reel and passed over a sheave mountedon the same shaft with the sheaves of the crown block utilized for the tackle cable. This caused the lighthoisting cable to lift on a line disposed a considerable" distance from the central axis of the derrick which caused binding of the joints of'the element lifted upon when it was desired to separate these at the floor of the derrick. A novel crown block in which this difiiculty was eliminated is shown in the patent to Edwin 0. .Bennett, No. 1,673,346, for crownblock, dated June. 12,

1928' In'the Bennett crown block, theglight i lifting sheaves are disposed'betweena pair of l-beains which rest upon the water'table of the derrick. The stationary block sheaves of the derrick tackle are rotatable on an axle disposed perpendicular to the axes of the light hoisting sheaves, and-which is mounted upon a pair of I-beams which are disposed in perpendicular relation with and rest upon the I-beanis carrying the light hoisting sheaves. In the Bennett crown block, the stationary .tackle sheaves are termed the'upper sheaves and the light hoisting sheaves disposed therebelow are termed the lower sheaves. The o truct n o h Bennet s e s b o stock.

thirty inches in d1a1neter,'itwas necessary makes it possible for the upper sheaves to be disposed close together so that the various turns of cable in the tackle are substantially parallel, which permits the traveling block to be drawn upward until it. contacts the crown block withoutfthe cable binding on the sheaves of either block. In usingthe Bennett crown block, therefore, drillers have found it diflicult to avoid the lower sheavesbeing darnaged by .the traveling block striking these,

and frequently fragments have been broken from the lower blocks which, falling downward through thederrick, have menaced the lives of the drilling crewworking on the floor, of the derrick. i

It is correspondingly an object of my invention to provide a crown block construction in which 'a pair of lower sheaves is protected from being damaged when the traveling block of the derrick tackle is liftedv into contact with the crown block.

Heretofore, the I-bearns, bywhich the lower sheaves of the Bennett crown blockwere supported, have been inside from standard rolled Owing to the", lower sheaves being that the I-beams on which the supported sheaves were mounted be twenty inches in height. In order to secure the desired compactness of the crown block with the lower beams of this height, the lower portion of theends of these I-beains were notched so as to receive-opposite wooden members of the water table of the derrick, and the shafts on which the lower sheaves rotatedwere mounted along the lower edges of these notched ,I-' 'bealns. This construction does, not provide adequate support for the lower sheaves, and a more rigid support for the lower sheaves has been found necessary;

It istherefore a further object. of my invention to provide a crown block of the Bennett type in which the supports for the lower sheaves thereof are of ample strength to rigidly support these sheaves'and, at the same time, owing to the form of their construction, to protect the lowersheaves against damage by the traveling block on its upward mov Inent.

n ther o je of my i ntio s to Pr Ill vide a crown block assembly having sheaves over which a cable extends, which cable also extends around a traveling block, lower sheaves disposed below the upper sheaves, and means for protecting the lower sheaves so that the traveling block cannot engage them.

Further objects and advantages will be made manifest in the following description and accompanying drawings in which a preferred embodiment of my invention is illustrated. Referring to the drawings, which are for illustrative purposes only:

Fig. 1 is a diagran'nnatical view illustrating a derrick on which the crown block of my invention is adapted to be used.

Fig. 2 is a fragmentary sectional view showing the manner of rigging the derrick tackle upon the crown block.

Fig. 3 is'a vertical sectional view through the crown block of my invention, partly in elevation, the sectioned portions of F ig. 3 being taken on planes indicated by the line 33 of Fig. 4.

Fig. 4 is a verti a1 sectional view taken as indicated by the line 44 of Fig. 3.

Referring specifically to the drawings:

Fig. 1 shows a typical well drilling derrick 10, which includes four inwardly sloping legs 11 which are interconnected and braced by girts 12 and struts 13. Mounted on top of the legs 11 is a water table 15 which is a four sided wooden structure having an inner opening about live feet square. Mounted upon the water table 15 is the crown block 16 of my invention.

As clearly shown in Figs. 3 and 4, the crown block 16 includes a lower frame work 18 and an upper frame work 19 which are disposed in crossed relation. The lower frame work 18 includes a pair of outer I- beams 20 which is secured as by bolts 21 to the water table 15. Disposed centrally within the water table 15, and mounted on opposite sides thereof so as to be parallel with each other and the side beams 20, are lower sheave beams 24. Each of the beams 24 includes a web 25, the outer end portions 26 of which are substantially 12 inches deep and rest upon the water table 15, while the central portions of the webs are substantially 33 inches in depth and extend downward over 21 inches into the square central space of the water table 15. Opposite sides of the upper and lower edges of each of the webs 25 are reinforced by angle irons 28 and 29, which conform to these edges and are riveted to the webs 25. Disposed between the beams 24, on opposite sides of the central axis of the derrick 10, are lower sheaves 30 which are pivotally mounted upon shafts 31 and 32, and which are supported in split bearing blocks 33 and 34 which are secured as by bolts 35 to opposite sides of the webs 25 of the beams 24, so that the bearings 33 and 34 are in horiupper zontal alignment with each other. The

sheaves 30 are preferably 30 inches in diameter, but it is to be understood that these dimensions are for the purpose of indicating proportion and are not essential to the invention.

The shaft 32 extends outward beyond the bearing 34, in which it is supported, and receives a small sheave 36, the purpose of which will be described later. v

It is to be noted that in the construction of the lower frame 18 of the crown block 16, the beams 24 extend downward some distance below the lower portions of the sheaves 30, and that the bearing blocks 33 and 34 upon which these sheaves are supported are secured to the webs 25 of the beams 24 at points substantially intermediate the upper and lower edges of these beams. Thus, not only is protection afforded to the sheaves 30, but the beams 24 are made much stronger than those previously used without increasing the height to which the crown block 16 extends above the water table 15 upon which it is mounted.

The upper frame 19 includes a pair of I-beams 40, held in spaced relation by spanners 41 and rigidly secured by bolts 42 to the I-beams 20 of the lower frame 18. Disposed between the beams is a series of stationary tackle-block sheaves 43 which rotate and are supported upon a shaft 44 resting on the I-beams 40 and secured thereto by clamps 45.

The derrick 10 has a floor upon which are rotatably mounted a bull wheel 51, a calf wheel 52, a sand reel 54, and a draw works having a cable drum 56. In using the lower sheaves 30 for light hoisting, a cable 58 may be unreeled from the sand reel 54 and run over one of the sheaves 30 so that it extends downward substantially 0n the axis of the derrick 10. The other sheave 30 is utilized by unwinding a cable 59 from the bull wheel 51, passing it over the other sheave 30 and extending it downward adjacent to the axis of the derrick.

In assembling the derrick tackle, a. traveling block 60 is provided which has a plurality of sheaves, one less in number than that of the sheaves 43 of the crown block 16. The cable 62 is extended from the drum 56 of the draw works 55 and wound consecutively about respective pairs of the sheaves 43 and the sheaves of the traveling block 60, so that the cable 62, after passing over the last of the sheaves 43, passes downward so that its direction is changed by the small sheave 36. and from this sheave extends to the calf wheel 52. The draw works drum 56 rotates on an axis parallel with the axis of the sheaves 43 so that the cable 62, passing between the draw works drum and one of the sheaves 43, lies substantially in the plane in which this sheave rotates so as not to wear the side flanges of this sheave. The calf wheel 52, on

the other hand, rotates on an axis perpendicular relative to the axis of the sheaves 43 so that the small sheave 36 is required to give the change'of direction to the cable 62 after it leaves the rest of the sheaves 43 over which it is wound and extends to the calf wheel 52.

As will be seen by observation of Fig. 2,

when the derrick tackle is operated by winding in the cable 62 held upon, the draw works drum 56 on the calf wheel 52- so as to raise the traveling block 60 into contact with the crown block 16, the traveling block 60 abuts against the lower edges of the beams 24 so that the sheaves 30 are entirely protected from damage by accidental contact with the traveling block 60. The angles 29 form wide abutting edges for the traveling block to engage.

It will be seen that my invention in its broadest conception consists or the particular shape of the lower sheave supporting means in order to protect them, and it further consists in the idea of providing a guard means at the lower part of the lower sheaves so that a traveling block cannot engage the lower sheave or sheaves. The guard means of the invention is shown as being integral with the lower sheave support means, but it is of course obvious that these parts could be made separate if desired.

I claim as my invention:

In a crown block construction the combination of: a frame including a pair of members, end portions of which are adapted to rest upon the water table of a derrick, and a central portion of which extends downwardly from said end portions; and a pair of lower sheaves rotatably mounted between said central portions of said frame members, the

' lower edges of said central portions being disposed below the lower portions of said 7 sheaves.

In testimony whereof, I have hereunto set my hand at Los Angeles, California, this 31 day of Dec., 1927.

WILLIAM D. DAVIDSON.

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