US2382054A - Portable crane - Google Patents

Description

Patented Aug. 14, 1945 A UNITED Y I-SYTATES PATENT OFFICE Y LadALIHei-cik, Lakewood, Ohio, assignor a The Hill Acme Company, Cleveland, Ohio, a cor-- poration of Ohio Application January 26, 1944; Serial No. 51.9,711

4 Claims.

This invention relates to portable cranes and particularly to that type of portable crane which is used in shops or warehouses for raising and lowering relatively heavy parts and for moving such-parts from one place to another on the floor. Such cranes are vcry'extensively used in machine shops for raising parts to be machined from the floor, conveying them to machine tools, lifting them into machine tools for machining, and lifting them out of the tools after machining.

For the purpose of moving from place to place, cranes of this type are usually provided with three wheel units which permit the crane, withits suspended load, to'be rolled over the floor of the shop. Floors of shops are usually not level, having high spots and hollows, which frequently cause the top of the crane standard to tilt laterally to such an extent that'the crane overturns unless extreme caution is exercised. The swinging of the suspended weight at a high elevation increases this danger of overturning, especially when the operator makes a sharp turn in rolling the crane over the floor. 'Ihe operator also frequently finds it necessary to pull sideways on the suspended load, when loading or unloading the crane, with the result that thecrane tips laterally to a dangerous degree and frequently overturns, causing personal injury and seriousdamage to the load and equipment.

It is to benoted that the tendency to overturn is counter-balanced practically only bythe weight Ill) of one half of the base; and in a crane, which must necessarily be light in weight for the sake of mobility, this counterbalancing efiect is negligible, and the danger of overturning is serious, once the resultant load force falls outside of the triangular area defined by the three spaced Wheel units.

The present invention is primarily directed to the preventionof, this inadvertent overturning, in a crane of the type referred to above.

'It is accordingly the prime object of this invention to provide means for preventing the-inadvertent overturning of arollablc floor. crane. either during loading, or rolling on the floor, or unload- It is a further objectof this invention to provide a crane of this type in which tilting, to a dangerous degree is prevented by auxiliary devices which function only when the crane tilts to a position in which it would, overturn, if itwere not for the action of these auxiliary overturn pre venting devices.

It is a further object of, this invention to pro vide suchoverturn preventing devices. which will not interfere with the normal operation or action of the crane under any circumstances either in loading, unloading or rolling along the floor and which will act as auxiliary rollers, in the event that the crane assumes a dangerous tilt outcf plumb when the crane is rolling along the floor.

A further understanding of the construction and operation and of the manner in which the novel features of this invention effect the above and further objects will become apparent from the following detail description and the annexed drawings, which set forth certain means embodying this invention, such disclosed means constituti-ng, however, but one of the forms in which the principle of this invention may be applied.

Referring to theanncxed-drawings:

Fig. 1 is: a side-elevation of a portable crane embodying this invention.

Fig. 21s a rear elevation of the crane illustrated in Fig. '1, a certain handle for maneuverin the crane being shownbroken awayat theaxle.

Fig. 3 isa plan sectional viewof the'crane illustrated inliigures 1 and 2, this view being taken frorirthe plane indlcated by line 3'-3', in Figures 1 and'2. v i

This improved portable {crane consists of a base frame indicated generally at I ,an upright standard mounted on the base frame indicated at I hoisting or lifting mechanism associated with the standard indicatedat 3, and rolling: means ind iarms. 5 is. preferably open and these arms-are spaced apart a distance sufiiciently wide' to accommodate the largest piecewhich is intended to be regularly handled. by the crane. As will appear from Fig. 3 the arms 5 are preferably of bent conformation, the front portions 1' oi the armsbfillflg. substantially parallel to the fore and aft: axis A-Xofthe crane (Fig.v 3-) and therearwardportions 8 of the arms 5 converging toward the rear connectingv bed or seat .6, the portions 1 and fl each forming. an apex or: elbow'at 9;, where they meet. v

The upright standard 2 is mounted uponuand preferably fi-xed'to the rear connecting bed or seat :5 of the base frames This standard comprises a substantially vertical column portion Hi and a forwardly curved. portion I12 terminating at a point substantially vertically above the space between the front ends ofthe arms 5. Thisstandardisformed, for thesake 0f lightness, Ofl four tubular members secured-together by zigzag rod lacing in order to combine-lightness and requisite strength. The base l3-of the column i-srpreterably connected to the rear-bed t byrwelding. 'Ilhi's shaft H which is in turn supported in a pair of bearing brackets I8, l8 Fixed to or integrally formed with the drum I6 is a worm gear 19 engaged by a worm 20 mounted on a shaft 2| which is rotatably mounted in a pair of bearings 22,

the shaft 20 being formed with a squared end adapted to receive a socketed crank handle 23. The axis of the drum preferably extends in a fore and aft direction and the axis of the worm extends in a transverse direction which arrangement aifords ready access to the crank handle from the side of the-crane. The drum is preferably located entirely within the confines of the vertical column portion H of the upright stand-, ard 2, as will readily appear from an inspection of Figures 1 and 2.

Fixed to the drum. l 6, preferably at its smaller end, is a cable 24. This cable is wound about the surface of the drum and at its free end extends upwardly over a pair of intermediate sheaves 25 and 26 and a terminal sheave 21, these sheaves being rotatably mounted on pins fixed in the curved portion I2 of the standard 2. From the sheave 21 the cable 24 loops downwardly and passes around a sheave 28 which supports a work lifting hook 29. The free end of the cable 24 passes upwardly from the sheave 28 to complete the loop and is preferably provided at its end with a hook 30 which, in the arrangement illustrated in Fig. 1, removably engages an eye 3|, whichis fixed to the forward end of the curved portion [2 of the standard 2.

When the loads to be lifted are relatively light and a faster speed of lift is possible the hook 30 may be removed from the eye 3| and hooked over the adjacent loop of the cable 24 at a point just above the sheave 28, as shown in dot and dash lines in Fig. 1.

It will be understood that a chain, rope or any 2 other equivalent may be substituted for the cable 24. It will also be clear that a hand wheel or any other device may be used instead of the crank 23. It will also be evident that, altho the hoisting mechanism in the present embodiment is manually actuated, power driven mechanism may be substituted.

The rolling means 4 consist of a plurality of wheel units which support the base frame as follows: At the front the base frame is supported on two spaced wheel units each of which consists, in the present embodiment, of a single wheel 33 rotatably mounted on a pin 34 fixed in depending flanges adjacent the front end of the forward portions 1 of the arm 5. The axes of the wheels 33 are located transversely with reference. to the fore and aft axis A-X and the plane of rotation of the wheels 33 is accordingly parallel to the fore and aft axis of the base. The rear of the base frame is supported on a wheel unit consisting of a pair of spaced wheels 35, 35

mounted on opposed ends of a curved crank r eccentric axle 36 whose central portion is journaled in a depending bearing 31 formed upon the lower end of a vertical king pin 38. This king pin 38 is mounted for oscillation about a vertical axis in a bearing 39 secured, by welding or otherwise, to the extreme rear of the connecting bed 6 andin a position substantially centrally of the base frame. Fixed to the axle 36, is the lower forked end of a handle 40, this handle being illustrated in Figures 1 and 3, in an operating position, that is, in a position which the handle occupies when the operator is drawing the crane over the floor. This handle 40 and the eccentric axle 36 are so positioned with respect to each other, that, when the handle 40 is raised to a substantially vertical position, the crank portion of the axle 36 in the bearing 31 of the king pin 38, and hence the rear of the base frame I, are lowered slightly, and when the handle is swung downwardly, the crank portion and the base frame, and hence the entire crane structure, are raised a slight amount. As a result of this position of the eccentric axle 36, with reference to the bearing 3''! just described, the weight of the crane normally tends to swing the handle 40 to a convenient vertical position.

Formed at the lower face of the frame and in a position vertically above the wheels 35, 35, are a pair of blocks 4|. These blocks are shown slightly vertically spaced from the Wheels 35, in the position of the parts illustrated in Figures 1 and 2. When, however, the handle 40 is raised to substantially the vertical position, the frame lowers sufficiently so that the blocks engage and rest upon the tops of the wheels 35, thereby serving as a brake acting on the wheels to prevent the rolling of the crane, this being the normal condition when the crane handle is not swung downwardly by the operator. When the handle 40 is slightly lowered from the vertical position the rear of the base frame is raised sufliciently so that the braking blocks 4| are freed from the wheels .35.

It will appear from the above description that the pair of spaced wheels 35, 35 move as a single unit and support the base frame at a point coincident with the king pin 38 at the extreme rear of the base frame and on the fore and aft center line of thebase frame.

It will further be evident that these wheels 35, 35 can swivel about the king pin 38 to an angle of 90 or more from the full line position shown in Figures 1 and 3, to the dot and dash line DOsi tion shown in Fig. 3, and that the base frame can therefor readily be rolled in any direction.

Located adjacent each elbow or apex 9 of each arm 5 of the base frame is located a safety wheel unit indicated in its entirety at 45. This unit is preferably of the caster type comprising a roll or wheel 46 mounted in the forked lower end 47 of a swivel pin 48 rotatably mounted for oscillation about a vertical axis in a vertical bearing 49 fixed in any desired manner to the arm 5. It is to .be noted that the lower point or bottom of the wheel 46 in the safety wheel unit 45 is spaced slightly above a plane tangent to the bottoms of the front wheels 33 and the rear wheels 35, that is, slightly above the floor line, as clearly appears in Fig, 1. safety wheel unit 45 above the fioor line is preferably so selected that there is'still slight clearance between the floor and the bottom of wheel unit 45 when the frame is in its lowermost position with its rear end resting on the wheels 35.

An inspection of the plan view, Fig. 3, will disclose that the safety wheels 45 are positioned outwardly of vertical planes AC and AB passing thru the center of the rear wheel unit and. the centers of the two front wheel units, respectively. It will be evident in fact, that the safety wheels are, further, located outwardly of vertical planes D-B and,EC passing thru the front'wheels The distance of the bottom of the 33, 33 and the centers of the spaced rear wheels 35, 35 On the corresponding sides of the crane, respectively, regardless of the angular position of the rear wheels; in other words, the swivelled safety wheel units are positioned laterally outwardly of the quadrilateral defined by the centers of the spaced front Wheels 33, 33 and the centers of the pair of rear wheels 35, 35.

An inspection of Fig. 3 will also disclose the fact that the safety wheel units are spaced apart a distance substantially equal to the space between the front wheels 33, 33 and that the safety Wheels are substantially alined with the front wheels.

33, 33 in a fore and aft direction. It will also be evident that the center to center distance of the safety wheel unit 45 and the front wheel 33 on the corresponding side of the crane is very nearly the same as the center to center distance of the safety wheel units 45 and the king pin 38 of the rear Wheel unit.

It will be evidentthat; in rolling on the floor, this crane normally travels on the two front wheel units 33 and rear wheel unit 35. If, however, one of the front wheel units should strike a high spot or projection on the fioor, that front wheel and that side of the frame would be lifted in proportion to the height of the projection. Such an interference on the floor would tend to cause the suspended weight to swing sideways and, if the height of the projection or intensity of impact is sufficient, the crane would normally overturn. In the present construction, however, the safety wheel unit engages the floor after only a ve y slight tilting of the base frame and this safety wheel therefor automatically prevents any excessive tilting of the frame. It will be apparent that a crane not provided with the safety wheels would tilt about the axis AB or AC, whereas a crane equipped with the safety wheels would tilt either about an axis passing thru one of the safety Wheel units and an adjacent wheel unit 33 or 35, and in either case the stabilizing moment would consist ofthe weight of the entire crane structure and its load.

In the event that one of the front wheels should roll into a depression on the floor the safety wheels would engage the floor after only a very slight drop of the front wheel and the crane would immediately be steadied before a tilt or list could create a dangerous overturning condition.

It is to be noted that, in view of the caster or swivel type of construction used for the safety wheels, no interruption of the rolling action will occur when the safety wheel engages the floor, regardless of the direction in which the crane is moving, nor will the direction in which the crane is moving be affected to any material extent by igie engagement of the safety wheels with the It will also be evident that in loading or unloading the crane, any slight tilting of the crane sideways, due to a side pull of the operator, will be resisted by the safety wheels, and that this action of the safety wheels will occur after only a very slight tilting of the crane, and as a result, inadvertent dangerous tilting of this. improved crane is eliminated.

Many modifications of this invention and its application will naturally occur to those skilled in this art and the present disclosure should therefor be considered as typical only, and I desire not to be limited to the exact constructions shown and described.

What I claim is: 1. In a portable crane in combination, a generally U -shaped base frame having forwardly projecting arms and a rear connecting bed, an upright standard supported on the connecting bed, hoisting mechanism associated with the standard for elevating a load straddled by the forwardly projecting arms, two laterally spaced wheel units supporting said arms, a central wheel unit supporting said connecting bed, and safety wheel units positioned on the arms laterallyoutwardly of vertical planes intersecting the centers of the front wheel units and the center of the rear wheel unit, said safety wheel units being approximately equidistant respectively, from said front and rear wheel units and the bottoms of the safety wheel units being positioned slightly above the plane defined by the bottoms of the wheels of the front and rear wheel units.

2. In a portable crane in combination, a base frame, an upright standard supported on the base frame, hoisting mechanism associated with the standard, two laterally spaced wheel units supporting the front end of the base frame, a central wheel unit supporting the rear end of the base frame, and safety wheel units positioned laterally outwardly of vertical planes intersecting the centers of the front wheel units and the center of the rear wheel unit, said safety wheel units being substantially equidistant respectively, from said front and rear wheel units, and being substantially alined in a fore and aft direction with the front wheel units, and the bottoms of the safety wheel units being positioned slightly above the plane defined by the bottoms of the Wheels of the front and rear wheel units.

3. In a portable crane in combination, a base frame, an upright standard supported on the base frame, hoisting mechanism associated with the standard, two laterally spacedwheel units supporting the front endv of the base frame, a central rear Wheel unit comprising a vpair of Wheels mounted on an axle swivelled on a vertical pin intermediate the pair of wheels supporting the rear end of the base frame, and safety wheel units fixed at points on the base frame positioned laterally outwardly of vertical planes intersecting the centers of the wheels of the front units and the centers of the wheels of the rear unit on the corresponding side of the base frame, when the axle is square with a. fore and aft axis of the base frame, the bottoms of the safety wheel units being positioned slightly above the plane defined by the bottoms of the wheels of the front and rear wheel units.

4. In a portable crane in combination, a base frame, an upright standard supported on the base frame, hoisting mechanism associated with the standard, two laterally spaced wheel units supporting the front end of the base frame, a central rear wheel unit comprising a pair of wheels- 7 mounted on an axle swivelled on a vertical pin intermediate the pair of Wheels supporting the rear end of the base frame, and swivelled safety wheel units positioned laterally outwardly of the quadrilateral defined by the centers of the spaced wheels of the front units; and the pair of wheels of the rear unit, the bottoms of the safety wheel units being positioned between the front and rear wheel units and slightly above the plane defined by the bottoms of the wheels of the front and rear wheel units.

LAD L. ruinous.

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