US 2012399 A
Description (OCR text may contain errors)
Aug. 27, 1935. M. MoLlNELLl SLUING MECHANISM FOR PORTABLE CRANES Original Filed March 24, 1932 Patented Aug. 27, 1935 UNITED `STATES SLUING. MECHANISM FOR PORTABLE CRANES Mario Molinelli, Milan, Italy YOriuginal application March 24, 1932, Serial No. 601,013. Divided and this application February 11, 1933, Serial No. 656,354. in Italy March 27,
` 3 Claims.
This application is a division of the application led on March 24', 1932, Serial Number 661,013. The invention relates generally to portable r cranes, such as are used for emergency jobs, as "t5 .for rescuing trains, motor cars, boats and the like, or forbuilding roads, railways and other buildings for `which it is not convenient to assemble a stationary crane,.whilst one must hoist very heavy M loads, as posts of telephonie or electric lines, l feeders etc., and more particularly it relates to an improved sluing mechanism for such cranes.
Sluing mechanisms are already known, in which an endless chain engages with a few teeth of a large sprocket wheel fixed to the jib, but such mechanisms have the same inconveniences as those comprising toothed wheel drives; the great 'sprocket wheel, which must generally be cast, is indeed very large and heavy, so that the weight of the crane andits dimensions result excessively high and the capacity of the crane must be kept small, if the crane has to be able to'travel on common roads.
Sluing `mechanisms are also known comprising a chain wound about a crown, which is provided .and preventingslipping of the chain around the crown. `When under load, however, the chain stretches out and its links do not engage with the indentations, so that slipping of the chain may occur. These mechanisms have also the inconvenience of too great dimensions and weight, since the crownmust be cast.
Sluing mechanisms are further known having ropes fixed by elastic means to a crown, but such mechanisms do not permit the crane to completely revolve about'its axis.
The object of the invention is a sluing mechanism having a very low weight and very small dimensions, so that theoverall width of the crane may be kept inside of limits suitable for a vehicle, and being at the same time simple, strong and able tomake the crane turn completely and in each direction about its axis.
In carrying out the invention a flexible means is provided, connecting a crown iixed on the superstructure or on the base of the crane to a driving wheel operated by a motor. The crown is provided with means adapted to transmit motion by allowing the flexible means to stretch. out, and which may consist of sprocket segments pivotally mounted on the crown and returned by a spring, when unloaded into a middle position between two rigid or elastic abutments. Means are also provided for tensioning the iiexible means. According to an improved embodiment of with a series of indentations connected by grooves (Cl. 'M -244) theinvention the flexible means is a roller chain and the crown has projecting annuli on which the said rollers bear, so that the chain may freely stretch out and slip about the crown.
The appended drawing illustrates diagrammatically a slueing mechanism according to the viiivention, and there are:
Fig. v1 a lateral View of a portion of a crane embodying a sluing mechanism according to the invention,
Fig. 2 a plan of same, and
Fig. 3 a sectional View of the crown.
According to the figures, the superstructure I running by rollers upon a circular rail carries a crown 2i about which a chain` 22 is wound and meshes with a sprocket wheel 2-3 x'e'dlori a shaft 2d driven by a sluing motor! 3l through aV gearing 25. The chain is tensioned in the vzone between wheel and crownl by a pair of sprocket wheels 26, 2l which may be pressed against it by means of screws 23, 29. The crown 2| has a special cross-sectional shape (see Fig. 3), permitting the chain to slip freely about it, its rollers rolling upon projecting annuli 43 of said crown, whilst the links l2 are engaged freely by suitably shaped grooves ll of. crown 2|, which are limited by rims i5, dii. Thus any friction between chain and crown is avoided and the chain may easily stretch itself under the stresses.
The crown is provided with cross members 30 on which are pivoted sprocket segments 3| carrying levers 32 subjected tothe action of va spring 3d fixed to the element 34 of the superstructure. The said segments 3l are arranged inside of slots of the crown and project with their toothed part from the external prole of the crown and mesh with chain 22. The segments 3| may rock about their pivots when drawn by the chain and prop up against abutments 35, 36, thus trailing the crown and the superstructure of the crane.
With this arrangement the inconveniences due to stretching of the chain under load or on account of wear, etc. are fully avoided; as a matter of fact, two or more such segments are provided, distributed along the periphery of the crown, and when the length of the portion of chain comprised between the segments varies on account of wear, etc., said segments rock about their pivots and allow the chain to maintain its tension by rolling freely with its rollers on the annuli 43 of the periphery of the crown. Thus the whole effort is transmitted from the chain to the crown through a single segment, since the others are normally in a non-contacting position.
When the segment carrying the load of the chain arrives, by revolving of the crown, at the point where the chain abandons the crown, it disengages itself from the chain. The latter slides then by a given amount along the periphery of the crown, until another segment, rocking about its pivot, rests against one of its abutments 35 or 36) and takes the load of the chain. The segment which has disengaged from the chain rocks about its pivot, under the pull of the spring 33, and rests in a position between abutments 35 and 36. When this segment arrives at the point where the chain applies itself again upon the crown, it engages again with the chain. In doing so, it may happen that the teeth of the'segment be positioned exactly before the gaps of the chain, and then engagement occurs very easily; but it may also happen that the teeth of the segment be more or less displaced from this ideal position and come into contact with the rollers of the chain. In this case the rollers will bear against the bevelled flanks of the teeth, and by rolling Valong the said flanks, they will push the teeth laterally, thus making the segment to rock about its pivot until a position is reached, where the teeth of the sprocket segment may exactly engage .Awith'the gaps of the chain. The distance of abutments 35, 35 is made so great that such a position may be found in any case; it sufces to this purlpose that the sprocket segment can rock about half a pitch in each direction from its resting position.l
The sluing mechanism described and illustrated is intended to be indicated merely as an example and many modifications thereof are possible within the invention, in accordance with the appended claims. Thus the grooved crown .maybe fixed either to the superstructure or to ,the turntable, whilst the sluing motor could be .amounted on the other of said parts; the motor may be either an electric, or a steam, a hydraulic,
.a pneumatic or an internal combustion engine, or .a driven shaft operated by any source of power, ,either separate or common with the driving means for lactuating the various. other parts of the crane; the flexible means for actuating the crown may be of any type other than a chain, such as an endless rope, a belt or the like; the coupling means may be other than sprocket segments, such as single yielding, projecting teeth;
they may rotate about any centre, even the centre of the crown itself, and they may also have no pivots, being slidable along a guide way or the like; said coupling means may rest against resilient, elastic or yielding abutments.
I am aware that prior to my invention portable cranes have been made with a sluing mechanism comprising endless flexible means driving a crown, therefore I do not claim such a combination broadly, but I claim:
l. In a sluing mechanism for cranes, a crown, a driving wheel, an endless flexible means driven by the driving wheel and operating about the crown, tensioning means for the flexible means, pivotally mounted members on the crown, to couple with the flexible means and pairs of stop devices iirmly joined with the crown, of which each one borders on two sides of one of the pivotally mounted members and limits displacement of said members in regard to the crown.
2. In a sluing mechanism for cranes, a crown, an endless flexible means operating about a. part of the crown and including rollers, ring struts jutting out from the crown, coacting with the rollers of the flexible means, said rollers resting and rolling on the said struts, pivotally mounted spokes on the crown, means on the spokes to join the said spokes with the flexible means, stop devices firmly fixed to the crown to limit the oscillations of the spokes caused by displacements of the iiexible means, and means for returning the spokes to their normal intermediate position when the joining means of the spokes become disengaged from the flexible means.
3. In a sluing mechanism for cranes, a crown having slots in the periphery, a driving wheel for the crown, a chain driven by the driving wheel and operating about the crown and including rollers and ring struts, toothed segments pivotally connected to the crown and projecting through the slots in the periphery of the crown and movable tangentially to thev periphery and capable of engaging the chain, pairs of stop devices connected with the crown, of which each pair is arranged to limit the oscillations of a segment, and springs for returning each segment to an intermediate position between the corresponding stop device pair when the segment becomes disengaged from the chain.