US2786580A

US2786580A - Portable derricks

Info

Publication number: US2786580A
Application number: US583321A
Authority: US
Inventors: Roy O Balogh
Original assignee: MCCABE POWERS AUTO BODY CO
Current assignee: MCCABE POWERS AUTO BODY CO; MCCABE-POWERS AUTO BODY Co
Priority date: 1956-05-07
Filing date: 1956-05-07
Publication date: 1957-03-26
Anticipated expiration: 1974-03-26

Description

March 26, 1957 R. o. BALOGH PORTABLE DERRICKS 3 Sheets-Sheet 1 Original Filed June 10, 1955 w M w m w a m M N R O O T Tl I A .O R

Y 8 R p kwm wm mm March 26, 1957 R. o. BALOGH 5 2,786,580

PORTABLE DERRICKS Original Filed June 10, 1955 s Shets-Sheet 2 INVENTOR. ROY 0. BALOGH BYW ATTORNEY March 26,, 19%? R. o. BALOGH 2,736,580

. PORTABLE DERRICKS Original Filed Jude 10, 1955 s Sheets-Sheet s ROY o.' BALOGH W ATTORNEY United States Patent PQRTABLE DERRICKS Roy 0. Balogll, Clayton, Mo., assignor to McCabc-Powers Auto Body (30., St. Louis, Mo., a corporation of Mis- .scuri Continuation of application-Serial No. 514,461, 'June.10, 1955. .This application .May 7, 1956, Serial No. 583,321

21 Claims. (Cl; 2128) with some type of derrick which can be used in lifting equipment up and down, settingpoles, removing worn out or defective poles and replacing them, and similar types of work. Such derricks are usually pivoted near the rear end of the truck body and extend forwardly in a substantially horizontal positionover the top of the body when the truck is moving from place to place. This position is usually referred to as the transport position. For actual use, the derrick is elevated into various upwardly and rearwardly-inclined positions usually referred to as -work positions. However, many types of work. encountered in the field, such as the lifting of heavy equipment from the truck body to the ground and then elevating it to the pole,- necessitates swinging the derrick downwardly over the rear end of the truck to a rearwardly extending horizontal position or even, in some cases, a rearwardly and downwardly inclined position. Thus, the derrick must swing through an arc in excess of 180 during these work-operations. Considerable difficulty in this respect is encountered with conventionaltypes of portable derricks byreason of the fact that conventional derricks cannot swing more than 180 and, in fact, many conventional derricks have an even more limited. arc of movement.

It is, therefore, the primary object of the present invention to provide a power operated vehicle-mounted or portable derrick which can be swung from inoperative transport position to uprightor work-position quickly, efliciently, and is capable of swinging through an arc substantially greater than 180.

It is also an object of the present invention to provide a vehicle-mounted derrick of the type stated which, when in operative position, can be swung forwardly and rearwardly by power driven means and is thus capable of reaching various-desired positions outwardly and downwardly to the rear of the truck body on which it is mounted.

It is a further object of the present invention to provide a portable derrick of the type stated which can be manipulated to and from transport position and into various operative positions by a single operator and is capable of a wider range of movement than conventional types of portable derricks.

With the above and other objects in view, my invention resides in the novel features of form, construction, arrangement, and combination of parts presently described and pointed out in the claims.

2,786,580 Patented Mar. 26, 1957 ice In the accompanying drawings (-three'-sheets) Figure l is a side elevational view jof'a utility maintenance truck equipped with aportable-derrick constructed in accordance with and embodying the present invention;

'Figure 2 is a-di agra-mmatic view of the hydraulidsys tem forming a part of the present invention;

Figure 3' is a fragmentary top plan'view'fofthe' utility maintenance-truck equipped with a portable emergenstructed in accordance with and embodying thejpresent invention;

Figure 4 is a fragmentary side elevational view showing *the derrick inupright or-work-position;

Figures Sand 6 are fragmentary-sectional views taken along lines 5-5 and 66, respectively,yofFigure 1;;

Figure 7 is a fragmentary perspective view of a modified form of portable derrick constructed in accordance with and embodying the present invention; and i Figure 8 is a fragmentary perspective view of a further modified form of portable derrick constructed in accord- :ance'with and embodying thepresent invention.

Referring now in more detail and by reference characters to the drawings, which illustrate practical embodiments of the present invention, A designates a utility maintenance truck equipped with a so-called utility body 1 provided at its forward end with 'the drivers cab 2 and having rearwardly extending side walls 3, 4, disposed in spaced parallel relation and includingaseries of builtin cabinets 5, 6, 7, 8, for the storage of tools, small parts, and similar items of equipment ordinarily used by rep'air crews. The side walls 3, 4, are spaced outwardly from eachother and, together with the rear an-'9 offthe cjab compartmentfdefine a cargo area a-which' is open; at the top and rear. Mounted on the floor 10 adjacentto'the crew compartment 2 is a conventional cable winch 'assembly 11 having a cable 12.

The floor 10 is extended rearwardly'beyondthe rear vertical faces of the side walls 3, 4, in the provision of an extension 13 provided on its under facewith depending clevis-brackets 14 from which ground jacks 15 are sus pended. Welded upon the upper face of the sidewalls 3, 4, adjacent the rear end thereof, are two saddle-shaped brackets 16, each provided with a pair of spaced

vertical ears

17,18, for supporting a horizontal pivotpin 19. l. At

its' forward end, each bracket 16 is similarly providedwith upstanding

parallel ears

20,21, for supporting ahori- Zontal pivot pin 22. Swingably mounted on the pivot pins 19 are U-shaped clevis elements 23 having tubular sockets 24 for receiving the lower ends of derrick legs .25,

the latter being'preferably welded in placewithin the sockets 24. l

The clevis elements 23 are, furthermore, provided with ears'26 for supporting pivot pins 27 which are operatively engaged in the ends of links 28 provided at theiropposite end-s with ,clevis'es 29. The clevises 29, in turn, embrace the ends of links 30 and are pivotally connected thereto by means of pivot pins 31 which extend through and are mounted in clevises 32 formed. on the end caps 33 of hydraulic cylinders 34 having piston rods 35,:the outer ends of which are pivotally mounted in brackets 36 welded to the derrick legs 25 as 'shown in Figure 1. Finally, the other end of'each link 30 is pivotally mounted on the pivot pin 22 of the bracket 'lti'withwhichit is operatively associated. By reference to Figure 1, it will be noted that when the derrick is in transport position the pivot pin 27 is above the center line of the derrick leg 25 and the pivot pin 19 is below such center line and well to the rearof the pivot pin 27. Similarly, the pivot pin 22 is below the pivot pin 19 and forward of the pivot pin 27 and the pivotpin 31 is substantially to the 3. in excess of 180 from the position shown in full lines to the position shown in dotted lines in Figure 1. It also should be noted that the hydraulic cylinders 34 are of conventional construction and are, therefore, not described herein in specific detail. The hydraulic cylinders 34 are connected through conventional hand-operated shut-otfvalves p and a main control valve V to a hydraulic system substantially as shown in Figure 2. The valve V may be of any conventional internal construction and includes a control handle 11 so that each of the two

cylinders

34, 34, will be operated simultaneously.

The derrick legs 25 are parallel with each other and with the longitudinal axis of the body 1, and at their upper ends are rigidly fastened into elbow fittings 1 which, in turn, connect with converging top-legs 37, the latter being operably connected at their outer ends inwardly toward each other by a sheave block assembly 38 having guide rollers 39.

The portable derrick is ordinarily lowered to inoperative or horizontal position as shown in Figure l and rests at its forward end in a somewhat L-shaped transport rack R rigidly carried on the forward Wall of the truck body 1 and extending upwardly and forwardly over the drivers cab 2. In order to raise the derrick to the operative position shown in Figure 4, oil is admitted to the cylinders 34, pushing the piston rods 35 outwardly and accordingly swinging the derrick upwardly and rearwardly. It will, of course, be understood that by manipulating the valve handle h different amountsof oil can be admitted to the

cylinders

34, 34, so that the derrick can be caused to assume virtually any position of angulation within the maximum limits of travel permitted by the component elements thereof. For example, the

cylinders

34, 34, can be adjusted so that the sheave block assembly 38 is located more or less vertically above the cargo area a in order that the cable 12 can be dropped vertically into the cargo area a for attachment to a heavy object, such as the transformer switch box or the like, whereupon the heavy article can be lifted vertically up from the floor of the truck and suspended. Thereupon, by admitting further oil into the

cylinders

34, 34, the sheave block assembly 38 can be swung rearwardly over and beyond the rear end of the truck body 1, thereby transporting the suspended heavy article rearwardly beyond the truck body into the clear, from which latter position it can be lowered to the ground or raised up to pole-height. When a heavy object such as a transformer is being lifted by the cable 12, the derrick A may be locked in the particular position to which it has been adjusted by closing the hand shut-off valves p.

It is also possible to provide a modified form of portable derrick of the type shown in Figure 7 which is substantially similar to the previously described portable dern'ck, which comprises two converging derrick legs 25' connected at their upper ends by a sheave block assembly 38' having guide rollers 39', which elements are substantially similar to the previously described derrick legs 25, sheave block assembly 38, and guide rollers 39. The derrick legs 25' are similarly mounted at their lower ends in clevis elements 23', which are, in turn, pivoted upon saddle-shaped brackets 16 and are provided with int-erconnecting links 28', 30', which are substantially identical with the previously described clevis elements 23, saddleshaped brackets 16, and

links

23, 30.

The links 28', 30, are connected pivotally to each other and interconnected transversely of the truck body by a horizontal pivot-forming bar 40 and the derrick legs 25' are likewise interconnected by a transversely extending horizontal bar 41 welded at its ends to the derrick legs 251 downwardly from the sheave block assembly 381. Pivotally connected between the midpoints of the bars 4d, 41, is a single hydraulic ram or cylinder 34'. This modified form of portable derrick functions in exactly the same manner as the previously described structure and differs therefrom only in the utilization of the single hydraulic 4 ram or cylinder 341. It will, of course, be understood in this connection that this modified type of portable derrick must either be employed for lighter types of work or the single hydraulic cylinder 34 and the

bars

40, 41, must be of very substantial size and strength. It will also be apparent that in the case of certain types of truck bodies the presence of the transversely extending

bars

40, 41, would impede the cargo area and work space within the truck body and, for such situations, it would he necessary to use a two ram boom rather than a single ram boom. These, of course, are matters of choice and selection which fall within the scope of the present invention.

Finally, it is also possible to provide a single legged one ram derrick embodying the present invention as shown in Figure 8. This derrick comprises a single derrick 25 which is provided at its outer end with a sheave block assembly 38" and at its lower end is securely welded into a clevis element 23", which is, in turn, pivotally mounted in a saddle-shaped bracket 16", which are substantially similar to the previously described clevis elements 23 and brackets 16. The clevis elements 23" and brackets 16" are interconnected by links 28" and 39', which are, in turn, pivotally connected by a pivot pin 31 and secured thereby in a clevis 32" formed on the end cap 33" of a hydraulic cylinder 34" having a piston rod 35", which is pivotally secured at its end to the derrick leg 2.5"v by means of a bracket 36". This one legged single ram derrick also functions in substantially the same manner as the previously described two legged derricks.

It should be understood that changes and modifications in the form, construction, arrangement, and combination of the several parts of the portable derrick may be made and substituted for those herein shown and described without departing from the nature and principle of my invention.

I claim:

1. A derrick comprising an approximately horizontal base, a boom pivotally mounted at its lower end upon the base for swinging movement into various positions and being adapted when in one extreme position to extend forwardly over the base, hydraulic cylinder means pivotally connected at its upper end to the boom outwardly therealong with respect to point of pivotal connection between the boom and the base, said hydraulic cylinder means extending downwardly along the boom and having its lower end spaced forwardly from the lower end of the boom when the boom is in said extreme position, first linkage means pivotally connected to the boom forwardly of the point of pivotal connection between the boom and the base, second linkage means pivotally connected to the base forwardly of the point of pivotal connection between the boom and the base, said first and second linkage means extending forwardly and being pivotally connected to each other and to the lower end of the hydraulic cylinder means so that said lower end of the hydraulic cylinder means will move along an arc upwardly and around the point of pivotal connection between the boom and the base.

2. A derrick comprising a base, a boom pivotally mounted at its lower end upon the base for swinging movement into various positions and being adapted when in one extreme position to extend forwardly over the base, hydraulic cylinder means pivotally connected at its upper end to the boom outwardly therealong with respect to point of pivotal connection between the boom and the base, said hydraulic cylinder means extending downwardly along the boom and having its lower end spaced forwardly from the lower end of the boom when the boom is in said extreme position, first linkage means pivotally connected to the boom forwardly of the point of pivotal connection between the boom and the base, second linkage means pivotally connected to the base forwardly of the point of pivotal connection between the boom and the base and below the point at which the first link is pivoted to the boom, said first and second linkage means extending forwardly and being pivotally connected to each other and to the lower end of. the hydraulic cylinder meansso that said lower end ofthe hydraulic cylinder means will move along an arc upwardly and around the -point of pivotal connection between the boom and the base.

3. -A derrick comprising an" approximately horizontal :base; a boom pivotally mounted at its lower end upon the base for swinging movement into various-positions and being adapted'when in one extreme position to extend forwardly over the base; hydraulic cylinder means-pivotally connected at its upper. end to the boom outwardly- .therealong with. respect to point of pivotal connection between the boom and the base, said hydraulic cylinder means extending downwardly along the boomand having its lower end spaced forwardly from the lower end of the boom when the boom is ,in saidextreme position, first linkage means pivotally connected to the boom forwardly 'of the point of pivotal connection between the boom and the base, second linkage-means pivotally connected to, the base'forwardly of the point of pivotal connection between the boom and thefbase, said links; furthermore, being pivoted to the boom and baserespectively on opposite sides of the point at which the boom is pivoted to the base, said' first and second linkage means extendlng forwardly and being. pivotally connected to each other and to the lower end of thehydraulic cylindermeansso that J said lower end of the hydraulic cylinder means will move along an arc upwardly and around the point of pivotal connection between the boom and the base.

4. A derrick comprising -a base, a boom pivotally mountedat its lower end upon the baseffor swinging movement into variouspositions and-being. adapted when in one extremeposition to extend forwardly over the base,

hydraulic cylindermeans pivotally connected at'itsupper end tothe boom *outwardlytherealong with respectto point ofpivotal:connectionbetween the boom and the base, said hydraulic cylinder means extending'downward- 'ly along the-boomand-havingitslower end spaced forwardly' from the lower end. of the boomr-when the boom is in said extremeposition;first linkage means pivotally connected to the boom forwardly of thepoint of pivotal connection between the boom and the base,'second linkage means pivotally connected to the base forwardly of the point of pivotal connection between theboom and the base and below the point at whichthe' first link is pivoted to the boom, said links, furthermore,- being pivoted to the boom andbase respectively onopposite sides of the point at whichthe boom is'pivo-ted to the base," said first and second linkage means extending forwardly and being pivotally connected to eachother and to thelower end of the hydraulic: cylinder meansso'that said lower end or the hydraulic cylinder means will move along an arc :upwardlyand around the point of pivotal connection between the boom and the base.

"5.A derricklcomprising a base, a boom pivotally mounted atits lower end upon the base for swinging movement into various positions and being adapted when in one extreme position to extend forwardly over the base,

hydraulic cylinder means pivotally connected at its upper end'tothe boom outwardly therealong with respect to :point of pivotal connection between the boom and the "base, said hydraulic cylinder means extending downwardly along the boom and having its lower end spaced for- "wardly from the lower end of the boom when-the boom is in said extreme position, first linkage means pivotally connectedto the boom forwardly of the point of pivotal cylindermeans so that said. lower end of. the hydraulic icylinderimeanswill' move along an arc upwardly and around the point of pivotal connection between the boom andthe-base.

6.-A- derrick comprising a base, a boom having two vconverging legs connectedat their upper ends for opera- ;tively supporting a. sheave, said'legs eachbeing-pivotally mounted at its lower end upon the base for swinging movement into various-position whereby said boom, when in one extremeposition, will extend forwardly over the base, a hydraulic cylinder pivotally connected at its upper-end to each leg outwardly therealong with respect to point of pivotal connection between such leg and the base, each of said hydrauliccylinders extending downwardly along the leg with which it is associated and'having its-lower end spaced forwardly from the lower-end of such leg when the boom is in saidextreme position each leg being provided with first linkage means pivotally connected thereto forwardly of the point of-pivotal connection between-'such'leg and the base, each leg also being provided with second'linkage means pivotally connected to the base forwardly of the point of pivotal connection between such leg and the base, said first and second linkage means extending forwardly and being pivotally connected'to each other and to the lower end of the hydraulic cylinder associated with such leg so that said lower end of such hydraulic cylinder will move along an are upwardly andaround the point ofpivotal connection between such leg and the'base.

7. A derrick comprising a base, a'boom having two converging legs connected at their upper ends for operatively supporting a sheave, said legseach being pivotally mounted at its lower end uponjthe base for swinging movement into various positions whereby said boom,-when in one extreme position, will extend forwardly over thebase,

a hydraulic cylinder pivotally connected at its upperend to each leg outwardly therealong with respect to point of pivotal connection between such leg and the base, each of saidhydraulic cylinders extending downwardly along 'the leg with which it is associated and having its lower end spaced forwardlyfromthe lower endofsuch leg when the boom is in said extreme position, each leg being providedwith' first linkage-means pivotally connected thereto forwardly of the point of pivotal connectionbetween suchleg and the 'base,-each leg also being provided with second linkage-means pivotally connected to the base forwardly of the point of pivotal connection between such leg and the base and below the'point at which the first link is pivoted to the leg, said first and second linkage means extending forwardly and being pivotally connected to each other and to the lower end of the hydraulic cylinder associated with such leg so that said lower end of such hydraulic cylinder will move along an arc upwardly and around the point of pivotal connection between such leg and the base.

' 8. A derrick compn'singa base, a boom having two converging legs connected-at their upper ends for operatively supporting a sheave, said legs each being pivotally mounted at its-lower end upon the base for swinging movement into various positions whereby said boom, --when 1n one extreme position, will extend forwardly over the base, a hydraulic cylinder pivotally connected at its upper end to each leg outwardly therealong with respect to point of pivotal connection between such leg and the base, each of said hydraulic cylinders extending down- "war'dly along the leg with which it is associated and having its lower end spaced forwardly from the lower end of such leg when the boom is in said extreme position,

each leg being provided with first linkage means pivotally connected thereto forwardly of the point of'pivotal connection between such leg and the base, each leg also being provided with second linkage means pivotally connected to the base forwardly of the point of pivotal connection between such leg and the base, said links, furthermore, being pivoted to'the leg and base respectively on opposite sides of the point at which the leg is pivoted to the base, said first and second linkage means extending forwardlyand being pivotally connected to each other ,and to thelower end of the hydraulic cylinder associated with such leg so that said lower end of such hydraulic cylinder will move along an arc upwardly and around the point of pivotal connection between such leg and the base. 1

9. A derrick comprising a base, a boom having two converging legs connected at their upper ends for operatively supporting a sheave, said legs each being pivotally mounted at its lower end upon the base for swinging movement into various positions whereby said boom, when in one extreme position, will extend forwardly over the base, a hydraulic cylinder pivotally connected at its upper end to each leg outwardly therealong with respect to point of pivotal connection between such leg and the base, each of said hydraulic cylinders extending downwardly along the leg with which it is associated and having its lower end spaced forwardly from the lower end of such leg when the boom is in said extreme position, each leg being provided with first linkage means pivotally connected thereto forwardly of the point of pivotal connection between such leg and the base, each leg also being provided with second linkage means pivotally connected to the base forwardly of the point of pivotal connection between such leg and the base and below the point at which the first link is pivoted to the leg, said links, fur thermore, being pivoted to the leg and base respectively on opposite sides of the point at which the leg is pivoted to the base, said first and second linkage means extending forwardly and being pivotally connected to each other end to the lower end of the hydraulic cylinder associated with such leg so that said lower end of such hydraulic cylinder will move along an arc upwardly and around the point of pivotal connection between such leg and the base.

10. A derrick comprising a base, a boom having two converging legs connected at their upper ends for operatively supporting a sheave, said legs each being pivotally mounted at its lower end upon the base for swinging movement into various positions whereby said boom, when in one extreme position, will extend forwardly over the base, a hydraulic cylinder pivotally connected at its upper end to each leg outwardly therealong with respect to point of pivotal connection between such leg and the base, each of said hydraulic cylinders extending downwardly along the leg with which it is associated and having its lower end spaced forwardly from the lower end of I such leg when the boom is in said extreme position, each leg being provided with first linkage means pivotally connected thereto forwardly of the point of pivotal connection between such leg and the base, each leg also being provided with second linkage means pivotally connected to the base forwardly of the point of pivotal connection between such leg and the base, said first and second linkage means extending convergingly forwardly and being pivotally connected to each other and to the lower end of the hydraulic cylinder associated with such leg so that said lower end of such hydraulic cylinder will move along an arc upwardly and around the point of pivotal connection between such leg and the base.

11. A derrick comprising a base, a boom having two converging legs connected at their upper ends for operatively supporting a sheave, said legs each being pivotally mounted at its lower end upon the base for swinging movement into various positions whereby said boom, when in one extreme position, will extend forwardly over the base, a first cross-bar extending transversely between said legs outwardly therealong with respect to point of pivotal connection between the legs and the base, hydraulic cylinder means pivotally connected at its upper end to said first crossbar, said hydraulic cylinder means extending downwardly between the legs and having its lower end spaced forwardly from the lower end of the legs when the boom is in said extreme position, each leg being provided with first linkage means pivotally connected thereto forwardly of the point of pivotal connection between such leg and the base, each leg also being provided with second linkage means pivotally connected to the base forwardly of the point of pivotal connection between such leg and the base, said first and second linkage means extending forwardly and being pivotally connected to each other, a second cross-bar extending transversely between said connected linkages for causing them to move simultaneously and means for connecting said second cross-bar to the lower end of the hydraulic cylinder means so that said lower end of the hydraulic cylinder means will move along an arc upwardly and around the point of pivotal connection between the boom and the base.

12. A derrick comprising a base, a boom having two converging legs connected at their upper ends for operatively supporting a sheave, said legs each being pivotally mounted at its lower end upon the base for swinging movement into various positions whereby said boom, when in one extreme position, will extend forwardly over the base, a first cross-bar extending transversely between said legs outwardly therealong with respect to point of pivotal connection between the legs and the base, hydraulic cylinder means pivotally connected at its upper end to said first cross-bar, said hydraulic cylinder means extending downwardly between the legs and having its lower end spaced forwardly from the lower end of the legs when the boom is in said extreme position, each leg being provided with first linkage means pivotally connected thereto forwardly of the point of pivotal connection between such leg and the base, each leg also being provided with second linkage means pivotally connected to the base forwardly of the point of pivotal connection between such leg and the base, and below the point at which the first link is pivoted to the leg, said first and second linkage means extending forwardly and being pivotally connected to each other, a second cross-bar extending transversely between said connected linkages for causing them to move simultaneously and means for connecting said second cross-bar to the lower end of the hydraulic cylinder means so that said lower end of the hydraulic cylinder means will move along an arc upwardly and around the point of pivotal connection between the boom and the base.

13. A derrick comprising a base, a boom having two converging legs connected at their upper ends for operatively supporting a sheave, said legs each being pivotally mounted at its lower end upon the base for swinging movement into various positions whereby said boom, when in one extreme position, will extend forwardly over the base, a first cross-bar extending transversely between said legs outwardly therealong with respect to point of pivotal connection between the legs and the base, hydraulic cylinder means pivotally connected at its upper end to said first cross-bar, said hydraulic cylinder means extending downwardly between the legs and having its lower end spaced forwardly from the lower end of the legs when the boom is in said extreme position, each leg being provided with first linkage means pivotally connected thereto forwardly of the point of pivotal connection between such leg and the base, each leg also being provided with a second linkage means pivotally connected to the base forwardly of the point of pivotal connection between such leg and the base, said links, furthermore, being pivoted to the leg and base respectively on opposite sides of the point at which the leg is pivoted to the base, said first and second linkage means extending forwardly and being pivotally connected to each other, a second cross-bar extending transversely between said connected linkages for causing them to move simultaneously and means for connecting said second cross-bar to the lower end of the hydraulic cylinder means so that said lower end of the hydraulic cylinder means will move along an arc upwardly and around the point of pivotal connection between the boom and the base.

14. A derrick comprising a base, a boom having two veyzsepso converging legs connected at their upper-ends for'operatively supporting a sheave,*said' legseach being pivotally mounted 'at its low'er endtipon the base for swinging movement into various positions whereby 'sald'boom,

*when in 'one extreme position, will extend'forwardly its upper end'to said first cross-bar, said hydraulic cylinder means extending downwardly between the legs and havingits 1 lower end spaced: forwardly from the :lower end of the-legs 'whenthe boom is in said extreme-position, -each leg being provided "with firstlinkage means pivotally connected thereto-forwardly of the p'oint'of pivotal connection between'such leg and the base, each leg also being provided-with second linkage means pivotally connected to the base forwardly of the point of pivotal connectionbetween 'such "leg and the base, and

below the point at which the first link is pivoted to the leg, said links, furthermore, being pivoted to the leg and base respectively on opposite sides of the point at which the leg is pivoted to the base, said first and second linkage means extending forwardly and being pivotally connected to each other, a second cross-bar extending transversely between said connected linkages for causing them to move simultaneously and means for connecting said second cross-bar to the lower end of the hydraulic cylinder means so that said lower end of the hydraulic cylinder means will move along an arc upwardly and around the point of pivotal connection between the boom and the base.

15, A derrick comprising a base, a boom having two converging legs connected at their upper ends for operatively supporting a sheave, said legs each being pivotally mounted at its lower end upon the base for swinging movement into various positions whereby said boom, when in one extreme position, will extend forwardly over the base, a first cross-bar extending transversely between said legs outwardly therealong with respect to point of pivotal connection between the legs and the base, hydraulic cylinder means pivotally connected at its upper end to said first cross-bar, said hydraulic cylinder means extending downwardly between the legs and having its lower end spaced forwardly from the lower end of the legs when the boom is in said extreme position, each leg being provided with first linkage means pivotally connected thereto forwardly of the point of pivotal connection between such leg and the base, each leg also being provided with second linkage means pivotally connected to the base forwardly of the point of pivotal connection between such leg and the base, said first and second linkage means extending convergingly forwardly and being pivotally connected to each other, a second crossbar extending transversely between said connected linkages for causing them to move simultaneously and means for connecting said second cross-bar to the lower end of the hydraulic cylinder means so that said lower end of the hydraulic cylinder means will move along an are upwardly and around the point of pivotal connection between the boom and the base.

16. A derrick comprising a base, a boom pivotally mounted at its lower end upon the base for swinging movement into various positions whereby said boom, when in one extreme position, will extend forwardly over the base, said boom being provided with first linkage means pivotally connected thereto forwardly of the point of pivotal connection between the boom and the base, second linkage means pivotally connected to the base forwardly of the point of pivotal connection between the boom and the base and below the point at which the first link is pivoted to the boom, said first and second linkage means extending forwardly and being pivotally connected to each other at their forward ends, and power driven extensible means pivotally connected *at'its upper end to the boom and operatively connected at*-its lower end :to*thepivotal'connection between the two links-whereby said er-tensible-means will simultaneously apply forward-andupwardiforce to the boom :and rearward force to said 1 last-named pivotal connection so that said lower end of such extensible means will move-alongan-arc upwardly andaround the point'ot' pivotal connectionibetween the boom and the base.

17.--A derrick comprising a base, a boom :pivotally mounted at its lower end upon. the base for'swinging movement with respect to the. base, hydraulic cylinder "means pivotally connected at its upper end to the boom,

alink pivotally connected at its one end to the base-and at its other end to the lower end of the hydraulic cylinder means, and means operatively connecting said link to the boom forswinging the link away'from the base around the point at which the link is pivoted'v to the base so as to produce movement of the 'pivotalconnection between the link--v and the lower-"end of .the hydraulic cylinder" means responsive to movementof. the boom.

18. A derrick comprising a base, a boom pivotally mounted at its lower end upon the base for swinging movement into various positions and being adapted when in one extreme position to extend forwardly over the base, hydraulic cylinder means pivotally connected at its upper end to the boom outwardly therealong with respect to point of pivotal connection between the boom and the base, said hydraulic cylinder means extending downwardly along the boom and having its lower end spaced forwardly from the lower end of the boom when the boom is in said extreme position, a link pivotally connected adjacent its one end upon the base and adjacent its other end to the lower end of the hydraulic cylinder means, and means operatively connecting said link and the lower end of the boom so that as the boom moves upwardly from said extreme position the link will also be swung upwardly around the point at which the link is pivoted to the base so as to produce corresponding upward movement of the pivotal connection between the link and the lower end of the hydraulic cylinder means.

19. A derrick comprising a base, a boom pivotally mounted at its lower end upon the base for swinging movement into various positions and being adapted when in one extreme position to extend forwardly over the base, hydraulic cylinder means pivotally connected at its upper end to the boom outwardly therealong with respect to point of pivotal connection between the boom and the base, said hydraulic cylinder means extending downwardly along the boom and having its lower end spaced forwardly from the lower end of the boom when the boom is in said extreme position, a connecting element pivotally mounted on the base and also being pivotally connected to the lower end of the hydraulic cylinder means, and means operatively associated with said connecting element and the lower end of the boom whereby to cause said connecting element to rotate about its pivotal connection with the base as the boom swings out of said extreme position and away from the base so that the point of pivotal connection between the lower end of the hydraulic cylinder means and said connecting element will move away from the base in the same direction as the boom.

20. A derrick comprising a base, a boom pivotally mounted at its lower end upon the base for swinging movement into various positions and being adapted when in one extreme position to extend forwardly over the base, hydraulic cylinder means pivotally connected at its upper end to the boom outwardly therealong with respect to point of pivotal connection between the boom and the base, said hydraulic cylinder means extending downwardly along the boom and having its lower end spaced forwardly from the lower end of the boom when the boom is in said extreme position, a connecting element pivotally mounted on the base intermediate the lower end of the hydraulic cylinder means and the point of pivotal connection between the boom and the base and also being pivotally connected to the lower end of the hydraulic cylinder means, and means operatively associated with said connecting element and the lower end of the boom whereby to cause said connecting element to rotate about its pivotal connection with the base as the boom swings out of said extreme position and away from the base so that the point of pivotal connection between the lower end of the hydraulic cylinder means and said connecting element will move away from the base in the same direction as the boom.

21. A derrick comprising a base, a boom pivotally mounted at its lower end upon the base for swinging movement into various positions and being adapted when in one extreme position to extend forwardly over the base, hydraulic cylinder means pivotally connected at its upper end to the boom outwardly therealong with respect to point of pivotal connection between the boom and the base, said hydraulic cylinder means extending downwardly along the boom and having its lower end spaced forwardly from the lower end of the boom when the boom is in said extreme position, a connecting element pivotally mounted on the base intermediate the lower end of the hydraulic cylinder means and the point of pivotal connection between the boom and the base and also being pivotally connected to the lower end of the hydraulic cylinder means, and means operatively associated with said connecting element and the lower end of the boom whereby to cause said connecting element to rotate about its pivotal connection with the base as the boom swings out of said extreme position and away from the base so that the point of pivotal connection between the lower end of the hydraulic cylinder means and said connecting element will move away from the base in the same direction as the boom and will follow the movement of the boom for a substantial portion of the path of movement of the boom.

No references cited.