US3161262A

US3161262A - Folding brace construction

Info

Publication number: US3161262A
Application number: US254057A
Authority: US
Inventors: Carl F Back
Original assignee: Sanderson Cyclone Drill Co
Current assignee: Sanderson Cyclone Drill Co
Priority date: 1963-01-28
Filing date: 1963-01-28
Publication date: 1964-12-15
Anticipated expiration: 1981-12-15

Description

Dec. 15, 1964 c. F. BACK 3,161,262

FOLDING BRACE CONSTRUCTION Filed Jan. 28, 1963 5 Sheets-Sheet l INVENTOR. g CARL F. BACK AT T 'ORNE YS Dec. 15, 1964 c. F. BACK FOLDING BRACE CONSTRUCTION 5 Sheets-Sheet 2 Filed Jan. 28, 1963 FIG.5

FIG.4

INVENTOR. CA RL F. BACK ATTORNEYS FIG.3'

Dec. 15, 1964 c. F. BACK FOLDING BRACE CONSTRUCTION 5 Sheets-Sheet 3 Filed Jan. 28, 1963 II? ll6 FIG.8

IOO

(/05 F I G 9 M R A 7?. W F au 7 G V L ZVIWDH F 7 m &4 M O H FIG.6

ATTORNEYS C. F. BACK FOLDING BRACE CONSTRUCTION Dec. 15, 1964 Filed Jan. 28, 1963 5 Sheets-Sheet 5 O 6 2 3w 5 0 5 5 2 &9

INVENTOR. H CARL F. BACK ATTORNEYS FIG. 13 33 United States Patent 3,161,262 FOLDING BRAQE CONSTRUCTIGN Carl F. Bach, Orrville, ()hio, assignor to The Sanderson Cyclone Drill (Iompany, Qrrville, @hio, a corporation of @hio Filed Jan. 28, 1963, Ser. No. 254,tl57 7 Claims. 3. 189-11) The present invention relates to a folding brace construction for a telescoping derrick structure. More specifically, the invention relates to a collapsing derrick structure and telescoping mast particularly adapted for use as a component of a portable well drilling machine mounted on a truck or vehicle or otherwise movable base or platform. Specifically, the invention relates to improved folding braces or collapsing supporting structures for a drilling machine including a mast formed with lower and upper relatively movable telescoping sections.

In general, the supporting folding brace structure for a telescoping mast of a drilling machine, according to the invention, includes diagonal braces, rear braces, tie braces and angle braces. The diagonal braces and tie braces are each pivotally connected to the base member of the mast. The diagonal braces and the rear braces have a common pivotal connection to the frame mounting the base member. This connection need not be detached during normal field use of the drilling machine. The angle brace has a pivotal connection to the upper member of the supporting mast. The rear braces, tie braces and angle braces have a common pivotal connection remote from the mast and the frame. Finally, the rear braces and the angle braces each comprises a pair of upper and lower rods having a relatively movable, spaced, parallel orientation maintained by slip joint brackets, with the angle braces (highermost in the supporting structure) having a locking mechanism which is automatically released during lowering of the mast.

Until now, the inventors experience has shown that the most satisfactory folding brace or collapsing supporting structure for the telescoping mast of a derrick structure has been of the type disclosed in United States Patent No. 2,905,280, granted September 22, 1959, to S. M. Weaver. In this prior art patent, the telescoping mast includes a base member 14 and a vertically extensible upper member 16. The supporting structure for the mast when the base and upper member are raised and in the extended positions includes a series of geometrically oriented and movable link braces.

In the said prior art patent, the uppermost pair of link braces (the symmetrical configuration of the supporting structure requiring two of everything unless otherwise mentioned) are angle rods 2 pivotally connected as at 21 to the upper end of the upper member 16. Lower down, tie rods 22 are pivotally connected as. at 23 to the upper end of the base member 14. The free or outer ends of these two sets of rods are connected together by a cross bar 32 and pivot connections 24. The length of the lower rod 22 is constant. However, the length of the upper rods 20 must change as the upper mast member is extended and contracted.

In the said prior art patent, each upper angle rod 20 includes two relatively movable link sections 20a, Ztlc interconnected by a locking type slip joint. Additionally, a locking means is provided to lock each pair of link sections in their extended position. This slip joint and locking means construction has not been entirely satisfactory in actual field use, and further presents certain cornplexities in construction with attendant increases in cost of manufacture.

Therefore, one object of the present invention is to provide an improved slip joint and locking means for the 3,161,262 Patented Dec. 15, 1964 upper folding brace portions of a telescoping derrick structure.

Referring again to the prior art as disclosed in Patent No. 2,905,280, the lower collapsible brace portions (that is, the link braces or rods connected to the base frame of the derrick) includes a pair of rear braces 25 and a pair of diagonal braces 28. At their upper ends, the rear braces are connected as at 24 to the outer ends of the rod 20, 22) of the upper brace portion. The upper ends of the diagonal braces are connected as at 23 to the upper end of the base member 14.

In the said prior art patent, these rear and diagonal braces 25 and 28 have detachable connections 27 and 3!) for connection to the derrick frame to support the mast in the extended position. These connections, which are of turnbuckle configuration having an eye and bolt construction, must be manually adjusted to tighten the mast in its erected position, and laboriously dismantled to lower the mast to the collapsed position for transport.

Therefore, another object of the present invention is to provide an improved construction for telescoping mast lower brace portions which are folding and collapsible, do not require tightening when the mast is extended, and which normally do not require the operator to partially dismantle the well drilling machine before leaving the. well site.

Other objects, as well as advantages, of the present invention will become apparent in view of the following detailed description and the attached drawings.

In the drawings:

FIG. '1 is a side View of a truck-mounted portable well drilling machine with a telescoping derrick structure according to the invention, collapsed for transport;

FIG. 2 is a fragmentary side view of the derrick structure of FIG. 1 during the first phase of raising;

FIG. 3 is a view sequentially following FIG. 2 during the phase of raising immediately prior to extension of the upper mast member;

FIG. 4 is an enlarged view, taken substantially as indicated on line 44 of FIG. 3, showing details of the improved collapsible brace rods used-in the lower brace portion of a derrick structure according to the invention;

FIG. 5 is a further enlarged view, taken substantially as indicated on line 5-5 of FIG. 4, showing details of the improved slip joint and locking mechanism for the lower brace portion;

FIG. 6 is still another sequential view, following FIG. 3, showing extension of the upper mast member:

FIG. 7, taken substantially as indicated on line 7-7 of FIG. 13, is a rear view of the derrick structure, with the mast extended and the upper and lower folding brace portions up and locked;

FIG. 8 is an enlarged detail, taken substantially as indicated on line 8-8 of FIG. 7, showing the trap or safety device used to prevent the extended upper mast member from slipping down;

FIG. 9 is a plan detail taken substantially as indicated on line 99 of FIG. 8;

FIG. 10 is still another sequential view, following FIG. 6, during the locking phase for the brace portions;

FIG. 11 is an enlarged view, taken substantially as indicated on line 11-11 of FIG. 3, showing details of the improved collapsible brace rods used in the upper brace portion of a dernick structure according to the invention;

FIG. 12 is a further enlarged view, taken substantially as indicated on line 12-12 of FIG. 11, showing details of the improved slip joint and locking mechanism for the upper brace portion;

FIG. 13 is the final sequential view, following FIG. 10, showing the mast extended and the upper and lower folding brace portions up and locked; and

FIG. 14 is a fragmentary plan View, taken substantially a 3 as indicated on line 1414 of FIG. 13, showing details of the diagonal rods of the lower brace portion.

In the drawings, the collapsing derrick structure is indicated generally by the numeral 20 and includes a frame formed by side members 21 and front and

rear cross channels

22 and 24. The frame is securely attached to a portable support such as provided by the bed of a truck or vehicle indicated at 25. The frame is further defined by vertical Samson channels 26 supporting top beams 27.

The base member 30 of the telescoping mast is pivotally mounted as at 31 on a bracket 32 carried at the upper rear of the frame. When erected, the foot of the base members 30 'rests'on a shelf 33 carried at the lower rear of the frame. To provide clearance for drilling tools the shelf 33 is at a slight downward angle to the horizontal frame members, preferably about 4 as shown, so that the derrick structure is inclined slightly away from the frame. The base member 30 \is moved around pivot point 31 by a power means indicated at 35. As shown, the power means 35 includes dual cylinders 36 mounted between frame side members 21. ously actuated by fluid under pressure supplied from a suitable source (not shown), and has an outwardly extending piston shaft 37 connected as at 38 to the base member 30. p 7

When the piston shafts 37 are fully extended, the base member 30 will be resting on the shelf 33 in the substantially vertical, erected position shown in FIGS. 3, 6, and 13. When the piston shafts 37 are fully retracted, the mast will be in the substantially horizontal, collapsed position shown in FIG. 1.

The upper member 40 of the mast is carried telescopically of the lower or base member 30 and longitudinally moved between contracted and extended positions by a suitable and conventional arrangement of pulleys and cables. For an illustration of a prior art mast hoist arrangement, reference is made to United States Patent No. 2,589,080, gran-ted March 11, 1952, to G Heinish (see FIG. 6 thereof).

The collapsible folding braces of the derrick structure include four pairs of primary link braces. The lower brace portion includes a pair of diagonal braces 50 and a pair of rear braces 51. The upper brace portion includes, apair of tie braces 52 and a pair of angle braces 53.

Referring to the detail view, FIG. 14, each of the lower diagonal braces 50 includes two substantially equal length upper and

lower rods

60, 61 located endato-end. and

hingedly connected as at 62. The lower end of each lower rod 61 is connected by a shackle pivot 63 and bracket 64 carried adjacent the end of a cross shaft 65 suitably secured to the upper front end of the derrick frame. .-In normal operation, each rod 61 remains permanently connected to the pivot 63 at all times, being disconnected only for purposes of construction or maintenance but not during conditions of field use. 7

Still referring to FIG. 14, the upper end of each. upper rod 60 is connected by a shackle clevis 66 and bracket 67 extending laterally from a side channel 68 of thebase member 30. For additional rigidity in the braces 50, if desired, a web plate and bracket 69, carrying an additional shackle clevis 70, may be used to connect each rod 60 to each base member bracket 68.

Referring to the detail view, FIG. 4, each of the lower rear braces 51 includes two substantially equal length upper and

lower rods

71, 72. As shown, the

rods

71, 72 are preferably fabricated from square, hollow, metal tubing. The

rods

71, 72 have a relatively movable spaced ably flanged so as to enclose or confine and slidably engage a parallel spaced lower rod 72. Onthe outer side Each cylinder 36 is simultaneof each bracket 74, and preferably attached thereto by the bolts 75, is an angle catch 76 of a lock mechanism for selective engagement with a latch carried on the upper brackets 73. To increase the rigidity of the brace portion 51, a tie rod 77 is preferably connected between the lower endsof the rods 71 and the brackets 74.

The upper brackets 73 are each secured, as by welding, to the upper end of a lower rod 72. The brackets 73 are suitably flanged to slidably confine an adjacent portion of the upper rods 71.

Referring to FIG. 5, the outer side of each upper bracket 73 carries a clevis 79 pivotally mounting the stub shaft 80 of a latch dog 81.: The latch dogs have a downwardly directed portion adapted to engage the outwardly projecting catches 76 on the lower brackets 74, when the mast is fully extended and the

brackets

73, 74 moved together (the condition of FIGS. 7 and 13) to lock together the

rods

71, 72 of the lower folding brace portions. v

For release of the latch dogs 81 to collapse the derrick structure for transport (FIG. 1), spring-loaded control rods 82 may be used, Referring again to FIG. 5, each rod 82 is carried by a flange 83 on the lower side of a bracket 73 and is connected to a crank 84 projecting inwardly from the stub axle 80. A spring 85 seated between the flange 83 and a collar 86 on the control rod 64, so that the lower end of the diagonal braces 50 and the lower end of the rear braces 51 have a common pivot connection. In normal operation, each rod 72 remains permanently connected to the pivot 87 (on. a common axis with pivot 63) at all times; being disconnected only for purposes of construction. or maintenance, but not during conditions of field use. 7

As is apparent from several of the side .views, such as FIG. 10, the upper end of the rod 71 of the rear braces 51, the outer endof the tie braces 52, and the lower end of the angle braces 53, also have a common pivot connection.

Referring to the detail view FIG. 11, the upper end of each upper rod 71 is carried by a long pivot shaft 90 and preferably carried adjacent each end thereof and confined thereon by a web-plate 91.

As shown in several of the side views, such as FIG. 10, each of the tie braces 52 are'fixed length rods pivotally connected as at 92 to the base member 30. It will be noted that, as shown, the pivot connection 92 is below the connection 66 for the rods 60 of the lower diagonal braces 50. Referring again to FIG. 11, the outer end of each rod 52 is connectedto the pivot shaft 90. For rigidity, the rods 52' are attached to a cross bar 93 rotatable on shaft 90, with additional reinforcement provided by web-plates 94, if desired.

Referring still to FIG. 11, each of the upper angle braces 53 includes two upperand

lower rods

97, 98. As shown, the

rods

97, 98 are preferably fabricated from square, hollow, metal tubing. The relative length of the rods 97,. 98 should be chosen so that the ratio of the length of the upper rods 97 to the length of the lower rods 98 be in the range 1.2-1.4/1.

The

rods

97, 98 have'a relatively movable, spaced, parallel or side-by-side orientation maintained by a set of slip joint brackets 1 00 The brackets 100 are each bolted, as at 101, to the lower end of an upper rod 97. The'brackets 100- are suitably flanged to slidably confine an adjacent portion of the lower rods 98. On the outer side of each bracket 100 and'preferably attached thereto by the bolts 101 is an angle catch 102 for selective engagement with the latch dogs of an improved upper brace locking mechanism 105. 7

Referring to FIG. 12, the lupper brace locking mech- [K1 ,3 'anism 105 includes front and rear cross plates 106 attached to opposite sides of the upper ends of the lower rods. The outer side cross plate 106 carries a pair of clevises 107 pivotally mounting a long latch shaft 108 extending between the upper end of each lower rod 98. A latch dog 109, having a downwardly directed portion adapted to engage the outwardly projecting catches 102 on the brackets 100, is carried adjacent each end of latch shaft 108.

The locking mechanism 105 further includes a rightangle lever arm 110 secured to the latch shaft and having an inwardly extending projection for attachment of the upper end of a latch release rod 111, as by bolt 112. The latch release rod 111 is a rigid member having a fixed and exact predetermined length so as to extend from the upper attachment point (110a) on the lever arm 110, which attachment point is behind or to the rear of the axis of shaft 108, to a lower attachment point provided by a mounting bracket 113 secured to the front face of the cross bar 93 connecting the lower ends of tie brace rods 52, which attachment point 113 is ahead or in front of the axis of shaft 90. A spring 115, seated between each upper rod 97 and confined by the plates 106 contacts the lever arm 110 and normally maintains the latch dogs 109 in position for locking engagement with the bracket catches 102. As described further below, the mounting and predetermined length of the latch rod 111 is such that the bias of spring 115 may be overcome and the upper folding brace portions 53 automatically released or unlocked, without manual intervention, during collapse of the derrick structure for transport.

Referring to the detail view FIG. 11, the lower end of each lower rod 98 is carried on the pivot shaft 90 between the upper end of a rod 71 and the cross bar 93.

As shown in FIG. 11, the upper end of each upper rod 97 of the angle braces 53 is fitted with a shackle pivot 116 for connection (see FIG. to a cross bracket 117 carried by the upper mast member 40 below the crown sheave 118.

To prevent the upper mast member 40 from accidentally slipping down when the mast is extended, a trap or safety device 120 may be located atop the mast base member 30. Referring to FIGS. 8 and 9, a trap plate 121 is mounted between brackets 122 carried by one of the cross plates 123 attached to opposite sides of the upper ends of the side channels 68 of the base member 30. When the trap plate is laying across the plates 123, support is provided for a cross bar 124 of the upper mast member 40. To release the safety device 120 prior to lowering of the derrick structure, the upper member 40 is raised a distance sufficient to clear the trap plate 121, which may be swung to the release position (shown in chain lines in FIG. 8) by a control cable 125 extending down to a position within reach of the operator.

The various components of the derrick structure described above function and move as follows:

(I) The base member 30 is raised from horizontal (FIG. 1), through an intermediate position (FIG. 2), to the vertical (FIG. 3), by cylinders 36;

(a) Referring to FIG. 3, when member 30 is vertical, the brace 50 has been unfolded and the

rods

60, 61 are aligned, the

braces

51 and 53 having become slightly elongated, the brace 52 moving downwardly around pivot point 92;

(11) Then, the upper mast member is raised from contracted position (FIG. 3) through intermediate positions (FIGS. 6 and 10) to maximum extension (not shown) for setting the safety trap 120 (FIG. 8), and slightly lowered to the normal extension position (FIG. 13);

(a) Referring to FIG. 6, the brace 53 becomes fully elongated with locking mechanism 105 fully engaged;

(b) Referring to FIG. 10, continued extension of the upper member 40 moves the pivot point 90 through an arc around pivot point 92.

An important advantage of the present invention is that in the intermediate positions, the derrick structure is 6 being supported during raising and would be unlikely to collapse in the event of a lift or power failure. In FIG. 3, the brace 50 is up and locked. In FIG. 6, brace 53 is locked, supplementing brace 50.

(0) Referring still to FIG. 10, the brace 51 becomes further elongated and brace 52 swings upwardly around pivot point 92;

(d) Concluding with FIG. 13, the brace 51 becomes fully elongated and locked in alignment with brace 53, brace 52 intersecting braces 51 and 53 at a right angle.

(III) To lower the derrick structure, first the locking mechanism for braces 51 is unlatched by manual pulldown of the rods 82, which are easily reached from the derrick frame.

(IV) Then, the mast members are brought to an exact vertical position (not shown) by a slight retraction of the shafts 37 of the cylinders 36. In this position, it is pos sible to raise the upper mast 40 a distance sufficient to release the safety device 120 by manual pull-down of the cable 125.

(V) Then, the mast member 40 is steadily lowered with the

braces

50, 51, 52 automatically folding. A indicated above, the lock mechanism for the upper folding braces 53 is automatically released without manual intervention. This is accomplished because of the mounting of the fixed length latch rod 111 between points 112 and 113. During lowering of the upper member 40, the common pivot connection for the

braces

52 and 53, as provided by the shaft 90 swings downwardly and inwardly toward the mast member 30. However, mounting of the rod attachment bracket 113 on the outer face of the cross bar 93 provides for an increasing radius of swinging movement so that the rod 111 is pivoted around latch shaft 108, overcoming the bias of the spring 115 and releasing the latch dogs 109 from engagement with the bracket catches 102. In practice, it has been found possible to determine the length of the rod 111 and the position of the bracket 113 to be such that the upper mast member 40 may be lowered at least a fourth of its extended height prior to automatic release of the locking mechanism 105. Thus, the derrick structure is being supported during the first phase of lowering and would be unlikely to collapse in the event of power failure.

(VI) After the unlocking of braces 53, the derrick structure is readily folded to the position of FIG. 1 by controlled retraction of the shafts 37 of the cylinders 36.

What is claimed is:

1. In a drilling machine having a frame and a retracting and extending mast, said mast having a base member 30 pivotally carried at the upper rear of the frame and an upper member 40 carried telescopically of the base member, four pairs of folding braces for said mast comprising:

a pair of diagonal braces 50, each of these said braces including hingedly connected upper and

lower rods

60, 61, the lower end of each lower rod being normally connected to said frame, the upper end of each upper rod being connected to said mast base member;

a pair of rear braces 51, each of these said braces including relatively movable spaced parallel upper and

lower rods

71, 72, the orientation of said rods being maintained by slip joint brackets, the lower end of each lower rod being normally connected to said frame, the upper end of each upper rod being carried by a pivot shaft 90, there being a mechanism on said brackets to lock together said rods when said mast is extended.

a pair of tie braces 52, each of these said braces including -a fixed length rod, one end of said rod being con nected to said base member, the other end of said rod being connected to said pivot shaft 90; and

a pair of angle braces 53, each of these said braces including relatively movable spaced parallel upper and

lower rods

97, 98, the orientation of said rod being maintained by slip joint brackets, the lower end of

joint brackets

73, 74, one set being attached to the lower end of an upper rod 71, the other set being attached to the upper end of a lower rod 72, each of said brackets being flanged to slidably confine a portion of an adjacent rod. 7

3. In a drilling machine according to claim 2, a mechanism on said brackets to lock together said rods 71, v72 in which the lower brackets 74 attached to the upper rods 71 have a catch 76 for selective engagement with a latch V mountlng said base member, said angle brace having a 81 carried by the upper brackets 73 attached to the lower rods 72.

4. In a drilling machine according to claim 1, said pair of tie braces 52 having a connection 92 to said base memher below the connection 66 of said upper rod of the diagonal braces 50 to said base member.

5. In a drilling machine according to claim 1, said'pair of tie braces 52'being attached at the outer end to a cross a bar 93 rotatable on said pivot shaft 90.

6. In a drilling machine according to claim 5, a bracket 113'on said cross bar 93 in front of the axis'of said pivot shaft 90, and said pair of angle braces 53 in which each of said brackets is attached to the lower end of an upper rod 97 and said mechanism to lock together said

rods

97, 98 includes a catch 102 on at least one of said brackets, a latch shaft 108 extending between the upper ends of each'lower rod 98, a latch 109 on said latch shaft forselective engagement with said catch, and a fixed length latch release rod 111 having one end connected to said latch shaft at a point 112 behind the axis of said latch shaft, the other end of said release rod being connected to said bracket 113 on said cross bar. j' i 7. Supporting folding brace structure for a telescoping masthaving diagonal braces 50, rear braces 51, tie braces 52 and angle braces 53, said diagonal braces and said tie braces each having a pivotal connection to the base member 30 of said mast, said diagonal braces and said rear braces having a common pivotal connection to the frame pivotal connection' to the upper member 40 of said mast, said rear braces, said tie braces and said angle braces having a common pivotal connection remote from said mast and said frame, said rear braces and said angle braces each comprising upper and lower rods having a relatively movable spaced parallel orientation maintained by slip joint brackets.

No referencescited. RICHARD W. COOKE, JR., Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,161,262 December 15, 1964 Carl F. Back It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 58, for "rod" read rods column 2, line 6, for "includes" read include line 9, for "rod 20,l 22) read rods (20, v22) column 3 line 14, for I "members" read member Signed and sealed this 11th day of May 1965.

(SEAL) Attest:

ERNEST W. SWIDER' EDWARD J. BRENNER Attesting Officer Commissioner of Patents

Claims

1. IN A DRILLING MACHINE HAVING A FRAME AND A RETRACTING AND EXTENDING MAST, SAID MAST HAVING A BASE MEMBER 30 PIVOTALLY CARRIED AT THE UPPER REAR OF THE FRAME AND AN UPPER MEMBER 40 CARRIED TELESCOPICALLY OF THE BASE MEMBER, FOUR PAIRS OF FOLDING BRACES FOR SAID MAST COMPRISING: A PAIR OF DIAGONAL BRACES 50, EACH OF THESE SAID BRACES INCLUDING HINGEDLY CONNECTED UPPER AND LOWER RODS 60, 61, THE LOWER END OF EACH LOWER ROD BEING NORMALLY CONNECTED TO SAID FRAME, THE UPPER END OF EACH UPPER ROD BEING CONNECTED TO SAID MAST BASE MEMBER; A PAIR OF REAR BRACES 51, EACH OF THESE SAID BRACES INCLUDING RELATIVELY MOVABLE SPACED PARALLEL UPPER AND LOWER RODS 71, 72, THE ORIENTATION OF SAID RODS BEING MAINTAINED BY SLIP JOINT BRACKETS, THE LOWER END OF EACH LOWER ROD BEING NORMALLY CONNECTED TO SAID FRAME, THE UPPER END OF EACH UPPER ROD BEING CARRIED BY A PIVOT SHAFT 90, THERE BEING A MECHANISM ON SAID BRACKETS TO LOCK TOGETHER SAID RODS WHEN SAID MAST IS EXTENDED. A PAIR OF TIE BRACES 52, EACH OF THESE SAID BRACES INCLUDING A FIXED LENGTH ROD, ONE END OF SAID ROD BEING CONNECTED TO SAID BASE MEMBER, THE OTHER END OF SAID ROD BEING CONNECTED TOSAID PIVOT SHAFT 90; AND A PAIR OF ANGLE BRACES 53, EACH OF THESE SAID BRACES INCLUDING RELATIVELY MOVABLE SPACED PARALLEL UPPER AND LOWER RODS 97, 98, THE ORIENTATION OF SAID RODS BEING MAINTAINED BY SLIP JOINT BRACKETS, THE LOWER END OF EACH LOWER ROD BEING CARRIED BY SAID PIVOT SHAFT 90, THE UPPER END OF EACH UPPER ROD BEING CONNECTED TO SAID MAST UPPER MEMBER, THERE BEING A MECHANISM 105 TO LOCK TOGETHER SAID RODS WHEN SAID MAST IS EXTENDED.