US1345008A - Portable general-utility derrick - Google Patents

Portable general-utility derrick Download PDF

Info

Publication number
US1345008A
US1345008A US363881A US36388120A US1345008A US 1345008 A US1345008 A US 1345008A US 363881 A US363881 A US 363881A US 36388120 A US36388120 A US 36388120A US 1345008 A US1345008 A US 1345008A
Authority
US
United States
Prior art keywords
mast
boom
derrick
standard
utility
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US363881A
Inventor
Joseph M Hill
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to US363881A priority Critical patent/US1345008A/en
Application granted granted Critical
Publication of US1345008A publication Critical patent/US1345008A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B66HOISTING; LIFTING; HAULING
    • B66CCRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
    • B66C23/00Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes
    • B66C23/18Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes specially adapted for use in particular purposes
    • B66C23/36Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes specially adapted for use in particular purposes mounted on road or rail vehicles; Manually-movable jib-cranes for use in workshops; Floating cranes
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B66HOISTING; LIFTING; HAULING
    • B66CCRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
    • B66C2700/00Cranes
    • B66C2700/03Cranes with arms or jibs; Multiple cranes
    • B66C2700/0321Travelling cranes
    • B66C2700/0357Cranes on road or off-road vehicles, on trailers or towed vehicles; Cranes on wheels or crane-trucks
    • B66C2700/0364Cranes on road or off-road vehicles, on trailers or towed vehicles; Cranes on wheels or crane-trucks with a slewing arm

Definitions

  • PatentedJun 29,1920
  • the obj ect'of the invention is to provide a portable crane or derrick which will have In the present,
  • the mast is made adjustable in length asis the boom, which is believed to be novel in the art.
  • a further object of the invention is to improve various details of derrick construction.
  • Figure 1 is a side elevation of one form of my device. 7 v
  • Fig.2 is a plan view thereof, but showing the boom at right angles to the position shown in Fig. 1, and showing the forward channel iron below the I-beams.
  • Fig. 3 is a vertical section taken through the center line of Fig.2. V
  • Fig. 1 is a fragmentary section on an enlarged scale of the upper'portion of the mast.
  • the truck 10 which forms the base ofmy device is built inrectangular form and consists of a pair of lon'gitudinalI- beams 11 and112 connected at their front and rear ends bychannel bars 13 and 14, the former being arrangedabove the I-beams and the latter below.
  • Thechannel iron 14 rests upon the rear axle on which is mounted the ground wheels 16, while the pivoted front axle carrying the relatively smaller ground wheels 17 supports a channel bar 18 to which is .secured in the usual manner a tongue 19 for transporting the device from place to place.
  • the frame is alsostiifened by a plurality of pipe sections 20 and 21 transversely arranged on and firmly secured to the I-beams 11 and 12.
  • the transverse channel orangle section 13 together with the similar section 27 supports the hoisting mechanism 28 which in the present showing consists of anordinary hand operated Windlass, but it will be readily understood that the invention contemplates the .use of any desired means for this purpose.
  • brace rods or stiffeners 29 are of the normal type and are secured to the central transverse members-20 and 21 at a mid point and then extend outwardly to the corners of the frame or in proximity thereto.
  • a cylindrical shaft 30 upon which all of the superstructure is supported is journaled in bearings 31 on each of the I-beams 11 and 12 so as t0v permit the free rotation of the mast rests in the bottom of the cavity' but when extended they may be pulled out of the socket member and there is practically no stress save the vertical thrust.
  • a loosely mounted'band 37 is fitted on the upper end of the socket member 33 andv carries an eye 38 for a purpose to be described later, the loose band being held against upward movement by'means of a collar shrunk on the mast just above the edge of the socket member or'p'referably by'anintegra'l lipor flange 39 on the socket member itself, as shown.
  • the mast 31 is held in vertical position between a U-shaped member, 40 and its removable clamp or hasp 41, these two'elements forming a detachable support for the mast, permitting it to be turned on its axle 30 into a nearly horizontal position at which time the mast rests in the saddle 42 on the rear channel iron 14.
  • the member 40 is supported from the frame work by means of a plurality of sloping and converging brace rods43 each stiffened by diagonal struts 44 joining the center of the brace rod to one of the side I-beams. 7
  • a band 46 is shrunk on the mast 31 to serve as a thrust bearing for the elevating frame or davit 47 which loosely embraces the mast andis freely rotated thereon, but is held against upward longitudinal movement by a shrunk collar 48 similar to the collar 46.
  • the collar 48 is arranged flush with the top of the mast and serves as a ferrule to protect such end in addition to its duty of holding the davit 47 in proper position.
  • the superstructure consists of a truss built of a telescoping boom 50, a forked standard 51 and a plurality of rods or diagonals connecting the top of the standard with the ends of the boom for the usual purpose.
  • the truss is strengthened and supported by a saddle member 52 pivoted by means of an integral lug 53 to a fork 54 rotatably mounted in ball bearings 55 in the head 56 of the post 58, the latter telescoping within the hollow mast 31.
  • the saddle member -52 is secured to the outer member 59 of the boom by means of a plurality of U-bolts 60 and also by means of the clamping action of the lower section 61 of the standard 51 and by a collar 62 shrunk on the end of the saddle and embracing the boom, this collar carrying at its lower end a swivel eye 63 adapted to receive a pulley block 64.
  • the standard 51 as previously mentioned is, of fork' shape, the two sides of thefork being fitted to embrace the pipe and saddle and being carried parallel at their upper sections receiving between them a wheel 62 over which is led a flexible steel cable 63" connected at the forward end by a swiveled eye bolt 64' in the end clamp 65 on the inner pipe 66 of the boom, and connected at the rear end to a threaded eye bolt 67 adjustably mounted in the rear end clamp 68 and held in adjustable position thereon by means of the nut 69.
  • the rear diagonals or truss rods 70 are each secured to the standard 51 by means of a bolt 71 passing through the truss rod eyes, this bolt also serving to pivotally connect a plurality of swivel plates 72 pierced to slidably receivethe free ends of the forward diagonal member 74, the latter being'permanently connected to the free or load end of the inner pipe 66 andbeing' locked in desired position on the swivels 72 by means of the lock nuts 7 5.
  • the front clamp, 65 is provided with a swivel eye 77 to receive a pulley block 7 8,
  • the post 58 has an enlarged head 56 in the bottom of the socket of which is located a ball race 87 to receivethe balls 55 which support the fork54, the latter having a short pintle 88 extending a short distance into the post to guide the same.
  • a hoisting cable 96 is led, from the 'load (not shown) over the pulley 78 and also over the pulley'wheel 97 between the legs of the fork 54 and is then turnedv by the pulley 64 on the farther side of the post down to a block 99 secured by means of a short piece of chain and hook to any convenient part of the truck, the only requirement being that the location of this block 99 shall be such as to give a straight pull from the Windlass 28 to the pulley 64 without interfering with the mast or braces.
  • bracket 100 In turning the superstructure about the mast I find it convenient to bolt a bracket 100 to the rear end of the pipe 92 andto connect a cable or rope to the free. end of such bracket, this enabling me to turn the entire truss about its vertical pivot by means of a pull practically parallel with the length of the boom.
  • a portable derrick consisting of a wheeled truck, a mast pivoted to said truck,
  • a boom pivotally mounted on said mast and readily detachable therefrom, and means for raising the boom out of contact with said mast.
  • a wheeled truck pivoted to the frame of said truck, a mast on said axle, means on said frame for receiving said mast when in collapsed position, means on said mast for holding said mast in vertical position, a boom rotatably mounted on said mast and detachable therefrom, and elevating means carried by said mast for raising said boom out of contact with said mast.
  • a portable derrick comprising a wheeled truck, a telescoping mast carried thereby, a boom pivoted to the inner section of said mast, and means carried by the outer section of said mast to aid in the raising and lowering of the boom and inner section.
  • a mast in a derrick structure, a mast, a superstructure pivoted thereto comprising a truss frame formed of a telescoping boom, a standard carried by said boom, tie rods carried by said standard and the inner section of said boom, and a tension member connecting the free ends of said boom.
  • a truss consisting of a telescoping boom, a standard on said boom, a tie rod permanently connected to the upper section of said standard and the free end of the larger section of said boom, a tie rod connected to the free end of the inner section of said boom and adjustably mounted in the upper end of said standard, and means for maintaining said tie rod in adjusted position on said standard.
  • a mast In a derrick, a mast, a boom pivoted thereto, a tension member connecting the free end of said boom with the lower por- 1 tion of said mast, a standard on said boom, a plurality of tie rods connecting said standard and the ends of said boom, and an ad justable flexible tension member for connectin together the two ends of said boom.
  • a frame In a portable derrick, a frame, wheels rotatably mounted on said frame, a hollow mast mounted on said frame to rotate about its connection with said frame, means for holding said mast in vertical position, av post slidable within said hollow mast, means for securing said post in desired adjusted position on said mast, a forked member pivotally mounted on said post, and a boom pivotally mounted in said forked member, whereby said boom may be pivoted about a horizontal axis and may be rotated about a vertical axis.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Jib Cranes (AREA)

Description

v J. M. HILL. PORTABLE GENERAL UTILITY DERRICK.
APPLICATION FILED MAR. 6, 1920.
Patented June 29, 1920..
3 SHEETS-SHEET 2.
Patented 11111629, 1920.
3 SHEETS-SHEET 3.
J. M. HILL.
PORTABLE GENERAL UTILITY DERRICK.
APPLICATION FIL ED MAR. 6. 1920.
UNITED STATES OFFICE.
J'OSEIPHVM. HILL, o'F'Tw INrALL s, IDA HO.
PORTABLE GENERAL-UTILITY DERRICK.
Specification of Letters Patent. PatentedJun 29,1920,
Application filed March 6, 1920. Serial No. 363,881.
To all whom it may concern:
.Be it known that I, JOSEPH M. HILL, a citizen of the United States, residing at Twin Falls, in the county of Twin Falls and State of Idaho, have invented certain new,
vice may be altered for a great variety of' work without departing from the fundamental principles of the invention.
The obj ect'of the invention is to provide a portable crane or derrick which will have In the present,
great range of. usefulness. structure the mast is made adjustable in length asis the boom, which is believed to be novel in the art. A further object of the invention is to improve various details of derrick construction.
In the drawings:
Figure 1 is a side elevation of one form of my device. 7 v
Fig.2 is a plan view thereof, but showing the boom at right angles to the position shown in Fig. 1, and showing the forward channel iron below the I-beams.
Fig. 3 is a vertical section taken through the center line of Fig.2. V
Fig. 1 is a fragmentary section on an enlarged scale of the upper'portion of the mast.
The truck 10 which forms the base ofmy device is built inrectangular form and consists of a pair of lon'gitudinalI- beams 11 and112 connected at their front and rear ends bychannel bars 13 and 14, the former being arrangedabove the I-beams and the latter below. Thechannel iron 14 rests upon the rear axle on which is mounted the ground wheels 16, while the pivoted front axle carrying the relatively smaller ground wheels 17 supports a channel bar 18 to which is .secured in the usual manner a tongue 19 for transporting the device from place to place. The frame is alsostiifened by a plurality of pipe sections 20 and 21 transversely arranged on and firmly secured to the I-beams 11 and 12. These pipe sections are hollow and slidably receive the neatly fitting solid rods 22 and 23. on the outer ends of which are located the platforms 24; and 25 which may be used for holding counterWeights when the boom of the derrick is at right angles'to the truck. When not in use the platforms are brought close against the side I-beam, in which posi;
tion they do not extend beyondfthe outer line of the ground wheels,.the rodsbeingfentirely .telescoped in'the sections 20 and 21,
nearly half the width of the truck, or in case only one platform is provided, which will be the usual equipment, the rods will extend entirely through the pipes and the amount of possible overhang is consequently doubled.
The transverse channel orangle section 13 together with the similar section 27 supports the hoisting mechanism 28 which in the present showing consists of anordinary hand operated Windlass, but it will be readily understood that the invention contemplates the .use of any desired means for this purpose.
The brace rods or stiffeners 29 are of the normal type and are secured to the central transverse members-20 and 21 at a mid point and then extend outwardly to the corners of the frame or in proximity thereto. v
A cylindrical shaft 30 upon which all of the superstructure is supported is journaled in bearings 31 on each of the I-beams 11 and 12 so as t0v permit the free rotation of the mast rests in the bottom of the cavity' but when extended they may be pulled out of the socket member and there is practically no stress save the vertical thrust. A loosely mounted'band 37 is fitted on the upper end of the socket member 33 andv carries an eye 38 for a purpose to be described later, the loose band being held against upward movement by'means of a collar shrunk on the mast just above the edge of the socket member or'p'referably by'anintegra'l lipor flange 39 on the socket member itself, as shown.
The mast 31 is held in vertical position between a U-shaped member, 40 and its removable clamp or hasp 41, these two'elements forming a detachable support for the mast, permitting it to be turned on its axle 30 into a nearly horizontal position at which time the mast rests in the saddle 42 on the rear channel iron 14. The member 40 is supported from the frame work by means of a plurality of sloping and converging brace rods43 each stiffened by diagonal struts 44 joining the center of the brace rod to one of the side I-beams. 7
At a point just above the member 40 a band 46 is shrunk on the mast 31 to serve as a thrust bearing for the elevating frame or davit 47 which loosely embraces the mast andis freely rotated thereon, but is held against upward longitudinal movement by a shrunk collar 48 similar to the collar 46. The collar 48 is arranged flush with the top of the mast and serves as a ferrule to protect such end in addition to its duty of holding the davit 47 in proper position.
The superstructure consists of a truss built of a telescoping boom 50, a forked standard 51 and a plurality of rods or diagonals connecting the top of the standard with the ends of the boom for the usual purpose. The truss is strengthened and supported by a saddle member 52 pivoted by means of an integral lug 53 to a fork 54 rotatably mounted in ball bearings 55 in the head 56 of the post 58, the latter telescoping within the hollow mast 31.
The saddle member -52 is secured to the outer member 59 of the boom by means of a plurality of U-bolts 60 and also by means of the clamping action of the lower section 61 of the standard 51 and by a collar 62 shrunk on the end of the saddle and embracing the boom, this collar carrying at its lower end a swivel eye 63 adapted to receive a pulley block 64. The standard 51 as previously mentioned is, of fork' shape, the two sides of thefork being fitted to embrace the pipe and saddle and being carried parallel at their upper sections receiving between them a wheel 62 over which is led a flexible steel cable 63" connected at the forward end by a swiveled eye bolt 64' in the end clamp 65 on the inner pipe 66 of the boom, and connected at the rear end to a threaded eye bolt 67 adjustably mounted in the rear end clamp 68 and held in adjustable position thereon by means of the nut 69. At its upper end the rear diagonals or truss rods 70 are each secured to the standard 51 by means of a bolt 71 passing through the truss rod eyes, this bolt also serving to pivotally connect a plurality of swivel plates 72 pierced to slidably receivethe free ends of the forward diagonal member 74, the latter being'permanently connected to the free or load end of the inner pipe 66 andbeing' locked in desired position on the swivels 72 by means of the lock nuts 7 5.
The front clamp, 65 is provided with a swivel eye 77 to receive a pulley block 7 8,
while the rear end boom clamp 68 has at its lower portion a heavy hook 79 intended to be connectedby a chain 80 to theeye 38 of the loosely mounted band 37 on the upper end of the socket member receiving the hollow mast, this chain acting as a tension member when the derrick is lifting a load, it being noted that as the boom swings about the mast, the band 37 will also swing so as to keep the hook 79, the eye 38, and the chain 80 in a single vertical plane.
The davit 47 previously mentioned is the mast and the upper reinforcing ferrule or collar 48. a V
The post 58 has an enlarged head 56 in the bottom of the socket of which is located a ball race 87 to receivethe balls 55 which support the fork54, the latter having a short pintle 88 extending a short distance into the post to guide the same. a For general convenience and also to prevent accidental displacement of the parts, itis preferred to cut a relatively narrow groove 89 in the lower portion of the fork 84 and to provide the head 56 with one or more screws '90 seating slightly intothis groove, so as to not prevent rotation, butlto effectually prevent longitudinalmovement of the parts.
It is the intention, however, when the post is to be raised, to throw the chain or rope around the post just below the head 56 and then run the rope over the pulley 83, which it will be noted will not have any tendency to lift the fork 54 out of its bearing in the head56.
In order to lengthen the boom,the nuts loosened by movement of the nut 69. This 75 are loosened and the cable 63 is also permits the inner tube 66 to be moved into or out of the outer pipe 92 and when it has been pulled to the desired position the bolted clamp 93 is fastened securely to the pipe 66 tightly against the shrunken ferrule 95 protecting the outer end of, the pipe92. The nuts 75 on the truss rod 74 are then looked in place and the cable 63' is made taut in the'usual way; A hoisting cable 96 is led, from the 'load (not shown) over the pulley 78 and also over the pulley'wheel 97 between the legs of the fork 54 and is then turnedv by the pulley 64 on the farther side of the post down to a block 99 secured by means of a short piece of chain and hook to any convenient part of the truck, the only requirement being that the location of this block 99 shall be such as to give a straight pull from the Windlass 28 to the pulley 64 without interfering with the mast or braces. By having one of the pulleys on-either side of the mast the load is well distributed and there is less tendency of the mast to tilt.
In turning the superstructure about the mast I find it convenient to bolt a bracket 100 to the rear end of the pipe 92 andto connect a cable or rope to the free. end of such bracket, this enabling me to turn the entire truss about its vertical pivot by means of a pull practically parallel with the length of the boom.
In order to have the two legs of thedavit 47 always parallel with the boom I preferably secure to the forked member 54 an extended arm 102 to which is hinged a retaining member 103 loosely fitting about the davit and constraining it to move with the boom, but not in any manner preventing the raising and lowering of the boom with respect to the mast to which the davit is seecured.
What I claim is:
1. A portable derrick consisting of a wheeled truck, a mast pivoted to said truck,
a boom pivotally mounted on said mast and readily detachable therefrom, and means for raising the boom out of contact with said mast.
2. In a portable collapsible derrick, a wheeled truck, an axle pivoted to the frame of said truck, a mast on said axle, means on said frame for receiving said mast when in collapsed position, means on said mast for holding said mast in vertical position, a boom rotatably mounted on said mast and detachable therefrom, and elevating means carried by said mast for raising said boom out of contact with said mast.
3. A portable derrick comprising a wheeled truck, a telescoping mast carried thereby, a boom pivoted to the inner section of said mast, and means carried by the outer section of said mast to aid in the raising and lowering of the boom and inner section.
4. In a derrick structure, a mast, a superstructure pivoted thereto comprising a truss frame formed of a telescoping boom, a standard carried by said boom, tie rods carried by said standard and the inner section of said boom, and a tension member connecting the free ends of said boom.
5. In a superstructure for a derrick, a truss consisting of a telescoping boom, a standard on said boom, a tie rod permanently connected to the upper section of said standard and the free end of the larger section of said boom, a tie rod connected to the free end of the inner section of said boom and adjustably mounted in the upper end of said standard, and means for maintaining said tie rod in adjusted position on said standard.
6. In a derrick, a mast, a boom pivoted thereto, a tension member connecting the free end of said boom with the lower por- 1 tion of said mast, a standard on said boom, a plurality of tie rods connecting said standard and the ends of said boom, and an ad justable flexible tension member for connectin together the two ends of said boom.
I. In a portable derrick, a frame, wheels rotatably mounted on said frame, a hollow mast mounted on said frame to rotate about its connection with said frame, means for holding said mast in vertical position, av post slidable within said hollow mast, means for securing said post in desired adjusted position on said mast, a forked member pivotally mounted on said post, and a boom pivotally mounted in said forked member, whereby said boom may be pivoted about a horizontal axis and may be rotated about a vertical axis.
JOSEPH M. HILL.
US363881A 1920-03-06 1920-03-06 Portable general-utility derrick Expired - Lifetime US1345008A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US363881A US1345008A (en) 1920-03-06 1920-03-06 Portable general-utility derrick

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US363881A US1345008A (en) 1920-03-06 1920-03-06 Portable general-utility derrick

Publications (1)

Publication Number Publication Date
US1345008A true US1345008A (en) 1920-06-29

Family

ID=23432114

Family Applications (1)

Application Number Title Priority Date Filing Date
US363881A Expired - Lifetime US1345008A (en) 1920-03-06 1920-03-06 Portable general-utility derrick

Country Status (1)

Country Link
US (1) US1345008A (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2560412A (en) * 1946-11-16 1951-07-10 Bert S Calvert Boom for excavators or the like
US3072272A (en) * 1959-05-19 1963-01-08 Leeford London Ltd Trenching machines
US3360144A (en) * 1965-10-23 1967-12-26 D Estrube Pierre Francois Car top boat loading and carrier apparatus
US3978989A (en) * 1975-02-07 1976-09-07 Avila Jr Fred Extensible and collapsible portable derrick
US20060169661A1 (en) * 2005-02-01 2006-08-03 Arjae Sheet Metal Company Inc. Manual boom lift method and apparatus

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2560412A (en) * 1946-11-16 1951-07-10 Bert S Calvert Boom for excavators or the like
US3072272A (en) * 1959-05-19 1963-01-08 Leeford London Ltd Trenching machines
US3360144A (en) * 1965-10-23 1967-12-26 D Estrube Pierre Francois Car top boat loading and carrier apparatus
US3978989A (en) * 1975-02-07 1976-09-07 Avila Jr Fred Extensible and collapsible portable derrick
US20060169661A1 (en) * 2005-02-01 2006-08-03 Arjae Sheet Metal Company Inc. Manual boom lift method and apparatus
US7293668B2 (en) * 2005-02-01 2007-11-13 Kdr, Llc Manual boom lift method and apparatus

Similar Documents

Publication Publication Date Title
US3836010A (en) Counter-balanced crane structure
US2327461A (en) Trailer derrick
US4138805A (en) Wheeled portable trailer substructure for elevatable drawworks, masts and setback tower
US3912088A (en) Boom structure
US5897101A (en) Collapsible engine hoist
US2139960A (en) Crane
US3209920A (en) Combination crane
US2290384A (en) Hoisting apparatus
US3899089A (en) Removable mounted hoist for pick-up truck
US3045837A (en) Rotary tower crane
US1345008A (en) Portable general-utility derrick
US3202299A (en) Mobile guy derrick and counter balancing crane
US2023790A (en) Portable crane
US3237781A (en) Outrigger counterbalance for cranes
US3028018A (en) Collapsible boom for mobile cranes
US3207347A (en) Boom attachment for lift truck
US2557484A (en) Truck crane
US2327015A (en) Apparatus for loading logs
US2549120A (en) Crane
US4386711A (en) Crane having stabilizer outriggers and vertically positionable jacks for same
US2470857A (en) Hoisting attachment for motordriven vehicles, such as tractors
US1311469A (en) Best available copy
US3197036A (en) Powered combination elevating ladder and crane hoist
US2025284A (en) Hoisting crane
US2379333A (en) Portable well-servicing apparatus