US 3032363 A
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Description (OCR text may contain errors)
May 1, 1962 N. F. CLAYBORNE MAGNETIC TIE PLATE LIFTER Filed Dec. 24, 1959 I 'IIIIIJIIIIIIIJ/ /VORMn/v l. Curse/aw:
ATTORNEY rates The invention relates to an apparatus for lifting and handling magnetic articles, and particularly pertains to a portable lifter for rail tie plates.
Devices for the lifting and handling of magnetic articles are well known, and magnets have long been used to handle scrap steel and other similar bulk material. Most magnetic lifting devices are used in conjunction with cranes and hoists; however, smaller hand operated devices are known for the handling of specialized articles as shown, for example, by U.S. Patent No. 2,285,440.
One of the. problems with hand operated magnetic lifting devices employing permanent magnets arises from the fact that strong magnets must be used if the lifter is to have sufiicient capacity to lift heavy articles; however, the use of a strong magnet increases the effort required to release the article from the lifter when it is desired to free the article, and the efiort required to release the magnet is objectionable in such a hand operated device if more than a several pound release force is necessary.
It is thus an object of the invention to provide a hand held magnetic lifting device wherein the magnets are of sufficient strength to permit a rail tie plate or other relatively heavy article to be lifted, yet the force required to free the article from the magnet is much less than the force holding the article.
A further object of the invention is to provide a magnetic lifter wherein the efiort required to free the magnets from the article being lifted is much less than the force imposed on the article by the magnets.
Another object of the invention is to provide a magnetic lifter having the above characteristics which is of simplified and economical construction, and wherein a minimum of moving parts are required.
Yet another object of the invention is to provide a magnetic lifter for rail tie plates and the like which may be readily handled by one man, and is of such rugged and simplified construction as to be virtually free of malfunctioning.
These and other objects of the invention will become apparent from the following description and accompanying drawings, wherein:
FIG. 1 is a partially sectioned elevational view of a magnetic lifter in accordance with the invention,
FIG. 2 is an elevational view of the magnet housing, comprising a section removing one of the sides thereof, showing the magnets and pole pieces in the flux transmitting relationship,
FIG. 3 is a bottom view of the magnet housing taken along line III-III of FIG. 1,
FIG. 4 is a plan sectional view of the magnet, pole pieces and magnet housing, taken along line IVIV of FIG. 2, and
FIG. 5 is a sectional elevational detail of one of the magnets and magnet supporting structure, taken along V-V of FIG. 1.
The general relationship of the components of the lifter in accordance with the invention will be apparent from FIG. 1, wherein it will be seen that the lifter includes a tubular stem having a T fitting 12 affixed to the upper end from which extend radially disposed handles 14. The magnet and pole piece housing, generally indicated at 16, is aflixed to the lower end of the stem 10, and the housing 16 is formed of a generally rectangular configatet 3,032,363 Patented May 1, 1962 uration. A rod 18 is supported within the stem 10, for axial movement thereto, and a slot 2% defined in the stem adjacent the upper end thereof permits a trigger or finger engaging ring 22 to extend through the slot and be afiixed to the rod 18. Thus, the operator, by grasping the handles 14, may bodily lift the assembled unit, and the finger ring 22 will be readily accessible to the operators finger without removing his hand from the right handle portion 14, FIG. 1. Thus, by inserting a finger into finger ring 22, the operator may axially raise and lower the rod 18 as desired.
The magnet housing 16 includes a rectangular plate 24 which is aflixed to the lower end of the stern. A die casting 25 including four rectangular side portions 26, is affixed to the plate 24 and extends therebelow to define a rectangular box or chamber. Screws or other conventional fastening means are employed to afiix the portions 26 to the plate 24. The bottom of the casting is defined by a bottom portion 28 which is integrally formed with the side portions 26, and it will be thus appreciated that the magnet housing 16 consists of a rectangular boxlike chamber defined by the four side portions 26, the upper plate 24, and the bottom portion 23. The bottom portion 28 is provided with several pole plates or pieces 32 which are cast into the bottom portion, and these pieces are thus afilxed to the portion 28. To prevent interference with the magnetic flux path, the stem 10 and housing 16 are constructed of a nonmagnetic material such as brass or aluminum, and the rod 18 is preferably con structed of steel. The pole pieces 32 are of a magnetic material such as steel, and may be of an alloy which, though a conductor of magnetic flux, has low flux residual characteristics.
As will be apparent from FIG. 1, the pole pieces 32 project slightly below the bottom portion 28, and the lower edge 34 of these pole pieces engages the article to be lifted, for instance, a rail tie plate. It will be also appreciated from the disclosures of FIG. 3 and FIG. 4 that the pole pieces 32 are of rectangular configuration and extend a substantial distance, approximately halfway, into the housing 16. The pole pieces are disposed in parallel spaced relation for a purpose which will be later apparent.
A magnet'suppo-rting plate 36 is affixed to the lower end of rod 18 by means of a threaded bore within the plate receiving the lower threaded end of the rod. The magnet holding plate 36 is of rectangular configuration and a slidable fit within the housing 16 defined by the side plates 26 is provided, whereby upon axial movement of the rod, the magnet holding plate will be raised and lowered within the housing. A plurality of sintered ceramic magnets 38 of rectangular configuration, three in the disclosed embodiment, are afiixed to the plate 36 in spaced parallel relation by means of U-shaped aluminum straps 40 which pass under and up the side of the magnets, and are affixed to the plate 36 by screws 42 or other type of fastening means. The magnets 38 are thus afiixed to the magnet plate in the desired relationship. The magnets are preferably of the sintereai ceramic type, as mentioned above, wherein the poles thereof are as indicated in FIG. 1. Referring to FIG. 1, it will be noted that the magnets 33 extend below the plate 36 a distance approximately half the height of the housing 16, such that when the plate 36 is in its uppermost position as shown in FIG. 1, the lower portions of the magnets 38 are related to the pole pieces 32, whereby lowering of the plate 36 and magnets will permit the magnets to be closely received within the voids defined between the adjacent pole pieces, whereby the magnets and pole pieces will be related as shown in FIG. 2, upon fully lowering of the plate 36.
The operation of the lifter is as follows: Under normal conditions, the weight of the rod 18, magnets 38, and plate 36 will cause the magnets to assume the relationship with the pole pieces illustrated in FIG. 2. At this position, the finger ring 22v will be in the dotted line relationship shown in FIG. 1, and the pole pieces 32 will have the maximum surface exposed to the magnets 38. The poles of the magnets are related whereby like polarity of adjacent magnets are adjacent a common pole piece, and thus the magnetic flux path between the pole pieces will be as illustrated by the small arrows. Upon placing the exposed edges 34 of the pole pieces on a magnetic article, such as a rail tie plate, the magnetic article will provide a path for the flux, and will be attracted to the pole pieces. The operator then raises or maneuvers the lifter and article as desired by grasping the handles 14. When the operator desires to release the tie plate from the pole pieces 32, he inserts his finger through or under the ring 22 and raises the ring to the full line position of FIG. 1. This movement raises the rod 18 and plate 36, which raises the magnets 33 above the pole pieces, as illustrated. Since the magnets are no longer adjacent the pole pieces, the pole pieces cease to conduct magnetic flux, and the tie plate is no longer attracted to them. Thus, the tie plate will be released from the lifter and will remain on the tie or other supporting surface on which it has been placed. The release of the tie plate is thus complete and the lifter may be used to handle and position the next tie plate in a similar manner. Merely by releasing the finger ring 22, the magnets return to the position of FIG. 2 and the process may be repeated.
The amount of effort required to lift the magnets fromthe position of FIG. 2 to that of FIG. 1 is little more than that required to overcome the: combined weight of the finger ring, rod, plate 36, and. magnets. This is due to the fact that the magnets 38 are not directly acting upon the tie plate, but are indirectly doing so throughthe pole pieces 32, and as the poles of the magnet are related at right angles to the primary path of magnetic flow, e.g. through the pole pieces in a vertical direction, the raising of the magnets relative to the pole pieces uniformly reduces the flux within the pole pieces and thereby releases the tie plate. Thus, it is not necessary to suddenly overcome the full magnetic force exerted by the magnets on the tie plate, but rather these forces are gradually weakened as the magnets move upwardly in relation to the pole pieces. It will be appreciated that the poles of the magnets are preferably related in a manner similar to that illustrated to prevent the magnets from being unduly attracted to the pole pieces themselves, and thus short-circuiting the flux. By opposing the like polarity of adjacent magnets, the pole pieces are relatively neutral in regard to magnetic attraction and, hence, the majority of the magnetic flux may be used in attracting the tie plate to the pole pieces. Also, any attraction of the pole pieces to the magnets will add little eifort to the operation of the device due to the sliding relationship of the magnets and pole pieces. While it would appear that the pole pieces at the extreme left and right of FIGS. 1 and 3 would be attracted to the left and right magnets, respectively, the magnetic field which surrounds the housing 16 seems to negate the attraction of the magnets to these particular pieces, and the magnet assembly is easily moved into and out of proximity with the pole pieces.
It will be thus appreciated that the lifter of the invention is capable of providing a strong magnetic pull, yet may be released from the article being lifted by a relatively weak force.
It will be understood that the invention may take forms other than that disclosed, for instance, the number of magnets and pole pieces may be varied, and that other modifications may be apparent to those skilled in the art without departing from the spirit and scope of the invention, and it is intended that the invention be defined only by the following claims.
1. A lifter for rail tie plates and the like comprising in combination, a tubular stem having upper and lower portions, a handle afiixed to the upper portion of said stem, a nonmagnetic housing affixed to the lower portion of said stem, a plurality of spaced parallel magnetic flux conducting pole pieces fixed in said housing each having planar side surfaces and an edge portion extending from said housing engageable with the article to be lifted, said edge portions collectively defining a lifting surface, a rod Within said stem and axially displaceable thereto, at least one magnet having opposite polarity lateral side surfaces movably mounted within said housing selectively removable from and positionable between the opposed side surfaces of adjacent pole pieces to vary the magnetic flux within said pole pieces, said magnet having a single pole associating with each adjacent pole piece, said magnet being connected to said rod whereby axial movement of said rod displaces said magnet relative to said pole pieces, and a hand actuatable member aflixed to said rod.
2. In a lifter as in claim 1, wherein four pole pieces are mounted within said housing and three magnets are mounted Within said housing for simultaneous cooperation with said pole pieces, like poles of adjacent magnets being adjacent a common pole piece.
3. A lifter for rail tie plates and the. like comprising, in combination, a tubular stem having upper and lower portions, a handle portion defined on the upper portion of said stem, an enclosed nonmagnetic housing defined on the lower portion of said stern, said housing including a bottom portion, a plurality of parallel, spaced, pole pieces having planar lateral side surfaces and an edge portion fixed within said housing, said edge portions extending through said bottom housing portion and collectively defining a lifting surface engagable with the article to be lifted, a magnet plate within said housing movable toward and away from said pole pieces, a plurality of spaced, parallel magnets having lateral side poles and peripheral edges, means fixedly mounting said magnets on said magnet plate, said magnets being selectively removed from and positionable between said pole pieces to vary the magnetic flux within said pieces, each magnet being positionable between the opposed side surfaces of adjacent pole pieces and the opposed lateral sides of adjacent magnets having like polarity and magnet plateoperating means associated with said magnet plate having an actuating member adjacent said handle portion.
4. In a magnetic lifter as in claim 3- wherein the means mounting said magnets on said magnet plate comprises a nonmagnetic band circumscribing a portion of the peripheral edge defined on each of said magnets and maintains the remainder of'said peripheral edge in engagement with said magnet plate.
References Cited in the file of this patent UNITED STATES PATENTS 2,503,467 Blind Apr. 11, 1950 2,628,122 Collins et al. Feb. 10, 1953 2,734,767 Donham Feb. 14, 1956 2,817,795 Miller Dec. 24, 1957 2,932,538 Holmes Apr. 12, 1960 2,954,257 Besuch et al. Sept. 27, 1960