US2953259A - Portable crane - Google Patents

Description

P 1960 R. M. WHITE 2,953,259

PORTABLE CRANE Filed NOV. 17, 1958 fl/mmev M WHITE,

IN VEN TOR.

if /w United States Patent 2,953,259 PORTABLE CRANE Richard Mitchell White, 235 Bennett Ave Long Beach, Calif.

Filed Nov. 17, 1958, Ser. No. 774,500

3 Claims. (Cl. 212-58) This invention relates to lifting apparatus and more particularly to an improved'portable crane.

It is a object of the present invention to provide an improved portable crane which is simple and eflicient in operation and economical in construction.

Another object of the present invention is to provide such a crane which is small and compact in size and especially adapted for the lifting of relatively small objects while the crane is attached to a truck or vehicle by which it is transported. g

A further object of the present invention is to provide a crane of the type described which has a telescoping boom which is aligned at all positions for ease of operation. The lifting cable of the crane is at all times aligned for minimum wear and abuse of the cable.

The present invention is an improved portable crane comprising a first and second telescoping tubular boom section wherein the first tubular section is mounted at the inward end thereof upon a crane base for pivotal movement about a vertical axis and adjustable pivotal movement about a horizontal axis. The second tubular section is slidably mounted within the first tubular section at the end of the outward end of the first section for telescoping movement therein. A cable drum positioned within the base is driven by an electric motor also within the base and a crane cable extends from the drum through the tubular section and over a cable positioning sheave at the outer end of the second tubular section.

The novel features which are believed to be characteristic of the invention both as to its organization and method of operation, together with further objects and advantages thereof will be better understood from the following description considered in connection with the accompanying drawing in which a presently preferred embodiment of the apparatus of the present invention is illustrated by way of example. It is to be expressly understood, however, that the drawing is for the purpose of illustration and example only, and is not intended as a definition of the limits of the invention.

In the drawing:

Figure 1 is a view in elevation of the presently preferred embodiment of the invention shown in the extended position;

mounting means of the boom thereon;

Figure 3 is a sectional view taken along line 3-3 of Figure 1;

Figure 4 is a partial sectional view of the outer end of the boom;

diameter and wall thickness which are determined for.

Figure 2 is a partial sectlonal view of the base and suflicient strength for the maximum weight to be lifted; The first tubular section is atfixed at the inner end thereof to the base section B as described hereinafter. The second tubular section 14 has an outside diameter substane ti-ally less than the inside diameter of the first tubular section 12 and is slidably mated with the first section 12 at the outer end 15 thereof. The relative diameters of the tubular sections 12 and 14 are predetermined to provide a longtudinally extending annulus between the sections of sufiicient thickness to accommodate positioning lugs 16 and 17 and a spacer guide sleeve 18. That is, the second tubular section 14 slidably telescopes within the first tubular section 12 and the lugs 16 and 17 and the sleeve 18 provide means for locking the boom sections against relative longitudinal movement and against rotation. In the presently preferred embodiment a guide or spacer sleeve 18 is aflixed to the inner surface of the first boom 12 extending longitudinally inward from theouter end thereof. The sleeve 18 has an outside diameter substantially equal to the inside diameter of the first tubular section 12 and an inside diameter substantially equalto the outside diameter of the second tubular section 14. Thus, the sleeve 18 fills the annulus proximate the outer end of the section 12 and furnishes a cylindrical bearing surface in which the second section 14 is slidable. The sleeve 18 defines a longitudinally extending slot 19 through the sleeve which for purposes of description and orientation is positioned about a horizontal radial plane of the boom A. Proximate the rearward end of the second tubular section 14 are positioning lugs 16 and 17 which are substantially diametrically opposedin this embodiment and longitudinally spaced. Relative to the orientation of the slot 19 the lugs 16 and 17 are positioned at opposite sides of a vertical plane through the boom section 14 and are spaced apart longitudinally such that the inward end of the outer lug 17 is spaced from the outer end of the inward lug by an amount sub stantially equal to but less than the length of the sleeve 18. The- lugs 16 and 17*are arcuate and have a thickness substantially equal to the thickness of the annulus, such that being aifixed to the outer surface of the second tubular section 14 they form bearing surfaces slidable on the inner surface of the first boom 12. The inward lug 16 is positioned proximate the inner end of the second section 14 and the width of the lugs is such that they are slid-able through the slot 19. Accordingly, installation of thesecond tubular section 14 into the first tubular section 12 is accomplished by rotating the second section 14 until the inward lug '16 is aligned with the slot 19 at the outer end of the first section 12. The second section 14 is then'moved inward until the outer lug 17 abuts the outer end of the first tubular section. At this point the inward lug has passed through the slot and the second section can be rotated until the outer lug is aligned with the slot 19. The second section is then moved inward to the fully telescoped position. To extend the boom to the extended separating position as shown in Figure 1, the second tube 14 is pulled'outwardly until the outer lug 17 contacts the sleeve 18, the section 14 is rotated until the lug 17 is aligned with and passes through the slot 19. The second section is then rotated to the position at which the sleeve is properly oriented, as described hereinafter. At this position both lugs 16 and 17 are misaligned'with the slot 19 and the sections 12 and 14 are longitudinally fixed; In addition, a recess 21 is'provided inthe outer end of the sleeve 18 which corresponds to the radial position of the outer lug 17 when the boom sections are properly oriented. By moving the second section 14 slightly inward the second lug moves into the recess 21 and relative rotation is prevented. It can be readily seen by one skilled in the art that various intermediate sets of lugs can be longitudinally positioned along the second tubular section 14 to provide intermediate extended positions of the boom A.

At the outer end 22 of the second tubular section 14 a cable 20 sheave 23 is positioned in accordance with this invention as shown in Figures 4 and 5. With respect to the orientation of the lugs 16 and 17 the sheave 23 is rotatably mounted in the vertical plane for rotation about a horizontally disposed shaft 24. The bracket 25 includes vertically disposed side plates 26 which are spaced apart by a distance substantially equal to but greater than the width of the sheave 23. The side plates extend upward beyond the radius of the sheave and a top plate 27 forms a top portion of the bracket. The bracket 25 also terminates at its inward position in a circular end by which it is affixed to the second tubular portion 14. The shaft 24 is mounted through the side plates 26 with the sheave positioned thereon. Thus, the cable 20 extending over the sheave is retained in position and engagement due to the side plates regardless of the direction of pull on the cable although the open end of the sheave mounting bracket allows the cable to extend straight outwardly or downwardly. The shaft 24 is so oriented that it is substantially horizontal when the first and second tubular sections are interlocked. Accordingly, the sheave is maintained in the vertical position.

The inner end 30 is affixed to the base section B for pivotal movement in both the horizontal and vertical plane. As shown in Figures 1 and 2 vertically oriented mounting plates 31 and 32 are affixed to the end 30 of the boom A, and are spaced apart by a distance substantially equal to, but greater than, the width of a cable pulley 33 which is interposed therebetween in the vertical plane. The mounting plates 31 and 32 are pivotally mounted upon a bearing shaft 35 which is supported by mounting brackets 36 and 37 which are aflixed to, and extend vertically from, a horizontal mounting member 38. The mounting brackets 36 and 37 are mateable with the mounting plates 31 and 32 and support the bearing shaft 35. The cable pulley 33 is also rotatably mounted upon the bearing shaft such that it is substantially tangential to the longitudinal centerline of the boom A. A tilt positioning pin 44 passes through a mateable pair of openings 41 through mounting plates 36 and 37 and through the respective openings 42 through plates 31 and 32, thereby fixing the angular position of the boom A. That is, a series of openings 42 are located upon the radius of the openings 42 with respect to the shaft 35. With the pin 44 removed, the boom A can be rotated about the axis 35 to the desired position where the respective opening 42 is provided. The pin is then inserted through the aligned openings and the boom is locked at the desired angular position.

The mounting member 38 is in turn mounted upon the base section B for pivotal movement about a vertical axis. In the embodiment shown the mounting member 38 is integral with a vertically extending cylinder 39. The mounting member and cylinder are mounted upon roller thrust bearings 45 affixed within a bearing support member 46 and support plate 47 of the base which are mateable therewith.

The support member 46 and plate 47 are positioned and supported by the base housing 48 which contains the drive section C. The drive section C comprises elements well known to the art including a winding drum 49 rotatably mounted within the housing which is driven by an electric motor 50 through suitable reduction gearing 51. Rotation of the drum 49 is controlled by a remote switch 52. The operator is thus able, by using the micromatic remote switch in one hand and guiding the boom with the other, to handle work which ordinarily requires one or two helpers.

The crane cable 20 thus extends from the winding drum 49 upward through the mounting cylinder 39 and over the cable pulley 33. The cable then extends through 4 the boom A, over the vertical sheave 23 and passes out of the boom through the cable bracket 25.

The boom A can be fixed to the stationary base 48 at any desired position about the vertical axis of rotation by inserting a fixing pin 53 through suitably aligned openings located in the flanges 38 and 47.

The present invention provides a portable crane which is compact and eflicient in operation. The cable is at all times maintained in the position at which it is subjected to the minimum amount of Wear. The boom is telescopic and is useable in any position from a truck or vehicle upon which it is mounted.

The heavy roller bearings at the base of the boom permit the boom to be turned easily through 360 and all moving mechanism of the apparatus except usable lifting cable is totally enclosed, thus eliminating the hazard of moving parts. The drive unit motor is operable from the battery of a vehicle in connection with which the apparatus is used and the power drain on a 6, 12 or 24 volt battery is very small for most commercial or other uses.

What is claimed is:

1. A portable crane comprising: a boom section, said boom section including a first tubular section; a second tubular section telescopically mounted within said first section, said second section having an outside diameter substantially less than the inside diameter of said second section, a cylindrical sleeve interposed between said first and second sections extending a predetermined longitudinal distance from the outer end of said first section, said sleeve defining a slot extending longitudinally through said sleeve, a pair of longitudinally spaced lugs afiixed to the outer surface of said second section, said lugs being longitudinally spaced by a distance substantially equal to but greater than said predetermined length of said sleeve, said lugs being radially misaligned on said second section and having a radial depth substantially equal to the distance between the outside diameter of said second section and inside diameter of said first section, said lugs having a width less than the width of said slot; a base section; a cable sheave mounted upon said boom proximate the outer end thereof, said sheave being in the vertical plane when said first and second tubular sections are aligned; a base section; means for mounting said first tubular section upon said base for pivotal movement about a vertical and horizontal axis; a driving means contained within said base, said driving means including an electrically driven cable drum; and a cable extending from said drum through said boom and from said boom at the end thereof opposed to said mounted end.

2. A portable crane comprising: a boom section, said boom section including a first tubular section; a second tubular section telescopically mounted within said first section, said second section having an outside diameter substantially less than the inside diameter of said second section, a cylindrical sleeve interposed between said first and second sections extending a predetermined longitudinal distance from the outer end of said first section, said sleeve defining a slot extending longitudinally through said sleeve, a pair of longitudinally spaced lugs affixed to the outer surface of said second section, said lugs being longitudinally spaced by a distance substantially equal to but greater than said predetermined length of said sleeve, said lugs being radially misaligned on said second section and having a radial depth substantially equal to the distance between the outside diameter of said second section and inside diameter of said first section, said lugs having a width less than the width of said slot; a base section; a cable sheave mounted upon said boom proximate the outer end thereof, said sheave being in the Vertical plane when said first and second tubular sections are aligned; a base section; means for mounting said first tubular section upon said base for pivotal movement about a vertical and horizontal axis;

a driving means contained within said base, said driving means including an electrically driven cable drum; 2.

cable extending from said drum through said boom and from said boom at the end thereof opposed to said mounted end; and means in combination with said driving means for operating said driving means from a position remote therefrom.

3. A portable crane comprising: a boom section, said boom section including a first tubular section; a second tubular section telescopically mounted within said first section, said second section having an outside diameter substantially less than the inside diameter of said second section, -a cylindrical sleeve interposed between said first and second sections extending a predetermined longitudinal distance jirom the outer end of said first section, said sleeve, a pair of longitudinally spaced lugs aifixed to the outer surface of said second section, said lugs being longitudinally spaced by a distance substantially equal to but greater than said predetermined length of said sleeve, said lugs being radially misaligned on said second section and having a radial depth substantially equal to the distance between the outside diameter of said second section and inside diameter of said first section, said lugs having a width less than the width of said slot; a base section; a bracket mounted upon said second section extending item the outer end thereof; a cable sheave mounted Within said bracket, said bracket including an upper surface above said sheave and opposed side plates positioned adjacent the sides of said sheave, said sheave being in the vertical plane when said first and second tubular sections are aligned; a base section; means for mounting said first tubular section upon said base for pivotal movement about a vertical and horizontal axis; a driving means contained Within said base, said driving means including an electrically driven cable drum; a cable extending from said drum through said boom and from said boom at the end thereof opposed to said mounted end; and means in combination with said driving means for operating said driving means item a position remote therefrom.

References Cited in the file of this patent UNITED STATES PATENTS 1,305,311 Sheldon June 3, 1919 1,345,304 Zied June 29, 1920 1,402,291 Harbinger Jan. 3, 1922 2,559,733 Pitman July 10, 1951 2,565,091 Reed Aug. 21, 1951

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