Counterweight for monorail hoists

A counterweight for a monorail hoist. The monorail hoist includes a single support beam and a suspended hoist assembly which is supported for movement along the support beam. The hoist assembly includes a support member which is transverse to the support beam. The counterweight is mounted on the support member. The counterweight is slidable along the support member to optimally balance the overall weight distribution of the hoist assembly. Once the counterweight is properly positioned to balance the hoist assembly, a locking device locks the counterweight to the support member to prevent any further movement of the counterweight along the support member. The locking device is also releasable to allow the counterweight to be moved to or removed from any location along the support member in order to accommodate any changes which may occur to the overall weight distribution of the hoist assembly. Preferably, a plurality of counterweights and cooperating locking devices are provided.

BACKGROUND OF THE INVENTION
 The invention relates to monorail hoists.
 Monorail hoists include a single support beam and a suspended hoist
 assembly for engaging and moving a load. Because the hoist assembly hangs
 from the single support beam, it is necessary to balance the overall
 weight distribution of the hoist assembly in order to prevent the hoist
 assembly from being cocked. It is known to weld counterweights to a hoist
 assembly to balance the hoist assembly.
 As generally known, a hoist assembly may be imbalanced for a number of
 reasons such as, for example, a difference in weight between the various
 components of the hoist assembly, or how the various components of the
 hoist assembly are assembled. One problem with the noted known manner of
 balancing a hoist assembly is that welding counterweights to the hoist
 assembly adds additional expense to the overall manufacturing and
 assembling costs for the hoist assembly. Another problem with this known
 manner of balancing a hoist assembly concerns repairs to or replacements
 of various components of the hoist assembly in the field. It is not
 uncommon that from time to time various components of a hoist assembly
 such as, for example, a motor or a gearcase, may need repairing or
 replacing. As can be appreciated, such a repair or replacement may alter
 the overall weight distribution of the components making up the hoist
 assembly. When the overall weight distribution is changed, some of the
 counterweights already welded to the hoist assembly will have to be
 removed and/or additional counterweights will have to be added. In any
 event, the removal of counterweights which have previously been welded to
 a hoist assembly, or the welding of additional counterweights to the hoist
 assembly, involves the use of costly equipment and requires time-consuming
 processes which also results in nonprofitable increased labor costs.
 SUMMARY OF THE INVENTION
 The present invention provides a counterweight for monorail hoists that
 alleviates the noted problems and other problems of the prior art. More
 particularly, the invention provides a counterweight that is slidable
 along a support member of a hoist assembly so that the counterweight can
 be properly located along the support member to optimally balance the
 hoist assembly. Once properly located, the counterweight is held in place
 along the support member by means other than welding.
 In one aspect of the invention, a releasable locking device is used to
 secure the counterweight to the support member. If the overall weight
 distribution of the hoist assembly is later changed, in order to balance
 the modified hoist assembly, the locking device is simply released so that
 the counterweight can be moved to or removed from any desired location
 along the support member. If additional counterweights are needed, the
 additional counterweights are simply mounted on the support member and
 moved to the appropriate location where they are then secured to the
 support member by their associated locking devices.
 Preferably, the locking device includes a locking bolt which is threaded
 into a threaded hole in the counterweight to engage a portion of the
 support member. In order to adjust the location of the counterweight along
 the support member or remove the counterweight from the support member,
 the locking bolt is simply unthreaded from the threaded hole to disengage
 the support member.
 The nonwelding locking device and adjustable counterweight of the present
 invention allow for optimum balancing of a hoist assembly in a more cost
 effective and efficient manner than previously known.
 Other features and advantages of the invention will become apparent to
 those skilled in the art upon review of the following detailed
 description, claims and drawings in which like numerals are used to
 designate like features.

Before the embodiments of the invention are explained in detail, it is to
 be understood that the invention is not limited in its application to the
 details of construction and the arrangements of components set forth in
 the following description or illustrated in the drawings. The invention is
 capable of other embodiments and of being practiced or of being carried
 out in various ways. Also, it is to be understood that the phraseology and
 terminology used herein is for the purpose of description and should not
 be regarded as limiting. The use of "including" and "comprising" and
 variations thereof herein is meant to encompass the items listed
 thereafter and equivalents thereof as well as additional items and
 equivalents thereof. The use of "consisting of" and variations thereof
 herein is meant to encompass only the items listed thereafter and
 equivalents thereof.
 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
 Illustrated in FIGS. 1 and 2 is a monorail hoist 10 embodying the
 invention. It should be understood that the present invention is capable
 of use in other monorail hoists and the monorail hoist 10 is merely shown
 and described as an example of one such hoist.
 The monorail hoist 10 includes a single support beam or rail 14. The beam
 14 is a standard I-beam having a bottom flange 18. A hoist assembly 22 is
 suspended from the beam 14. The hoist assembly 22 includes a pair of
 suspension trolleys 26 and 28 which include rollers 30 that run along the
 bottom flange 18 of the beam 14. The hoist assembly 22 also includes a
 frame 34 which is supported by the trolleys 26 and 28, and which includes
 a pair of side plates or members 42 and 46 which extend parallel with the
 beam 14.
 The hoist assembly 22 further includes a hoist drum 38 supported by the
 frame 34. The hoist drum 38 is generally transverse to the beam 14 and
 extends between the side members 42 and 46. A hoist rope 50 is
 conventionally wound around the hoist drum 38 and a load engaging device
 54 is coupled to the hoist rope 50 for vertical movement in response to
 rotation of the hoist drum 38. The load engaging device 54 is located
 directly beneath the beam 14 for maximum load carrying capacity. The load
 engaging device 54 may be a conventional bottom block as shown.
 The hoist assembly 22 also includes a hoist motor 58 for rotating the hoist
 drum 38. A gearcase 62 is coupled to the hoist motor 58 and to the hoist
 drum 38. The hoist assembly 22 further includes a brake device 66,
 preferably an electric brake, for stopping the rotation of the hoist drum
 38. The hoist motor 58, the gearcase 62 and the brake device 66 are
 supported by the frame 34. The hoist assembly 22 also includes control
 cabinets 70 and 74 which are supported on the frame 34.
 The monorail hoist 10 thus far described is well known in the art and
 further description is therefore not needed.
 With continued reference to FIGS. 1 and 2, the frame 34 includes a support
 member 78 which is perpendicular to the beam 14 and which extends between
 the side members 42 and 46. A plurality of counterweights 82 are mounted
 on the support member 78 for balancing the hoist assembly 22. The
 counterweights 82 are advantageously slidable along the support member 78
 so that the hoist assembly 22 can be properly balanced. Once balanced, as
 will be further explained below, the counterweights 82 are held in place
 on the support member 78 by locking devices 84.
 Referring now to FIG. 3, the support member 78 is preferably a tube having
 a rectangular cross-section including a top side 86, a bottom side 90, and
 opposite vertical sides 94 and 98 which extend between the top side 86 and
 bottom side 90. The support member 78 includes a pair of spaced apart
 upper corners 102 and 106 which are defined by the top side 86 and sides
 94 and 98. The support member 78 also includes a pair of spaced apart
 bottom corners 110 and 114 which are defined by the bottom side 90 and
 sides 94 and 98.
 With continued reference to FIG. 3 and in conjunction with FIG. 2, each
 counterweight 82 is substantially "U" shaped, although the counterweights
 82 may be of various shapes and sizes consistent with the principles of
 the present invention. Importantly, the counterweights 82 must cooperate
 with the support member 78, such that the counterweights 82 can be
 slidable along the support member 78 and the counterweights 82 can be
 removably and adjustably attached to the support member 78.
 Each counterweight 82 includes a first vertical leg 118, a second vertical
 leg 122 and a third horizontal leg 126 which extends between the leg 118
 and the leg 122. The leg 118 has a vertical dimension A which is greater
 than a vertical dimension B of the leg 122 (FIG. 3). The leg 118 also has
 a horizontal dimension C which is greater than a horizontal dimension D of
 the leg 122 (FIG. 2). The leg 118 includes a threaded hole 130 which
 extends completely through the leg 118 and which is preferably parallel to
 the beam 14 (FIG. 2). When a counterweight 82 is mounted on the support
 member 78, the top side 86 of the support member 78 engages the horizontal
 leg 126 of the counterweight 82, the vertical side 94 of the support
 member 78 engages the leg 118 of the counterweight 82, and the vertical
 side 98 of the support member 78 engages the leg 122 of the counterweight
 82. As should be understood, given the configuration of the support member
 78 and the mating configuration of each counterweight 82, the
 counterweights 82 can be slid along the support member 78 until the hoist
 assembly 22 is properly balanced.
 The locking device 84 preferably includes a locking bolt 134. The locking
 bolt 134 may be a hex-socket screw or any number of various types of bolts
 or screws in accordance with the principles of the present invention. Once
 a counterweight 82 is properly positioned along the support member 78, the
 associated locking bolt 134 is threaded into the associated hole 130 to
 engage the support member 78, thereby substantially preventing further
 movement of the associated counterweight 82 along the support member 78.
 In a preferred embodiment, for maximum holding capability, the locking
 bolt 134 contacts the bottom corner 110 of the support member 78 (FIG. 2).
 A lock washer 138 may be used with the locking bolt 134 to prevent the
 locking bolt 134 from unthreading. Conventional thread locking fluid may
 be used in place of the lock washer 138. Alternatively, conventional
 thread locking fluid can be used in combination with the lock washer 138.
 The locking device 84 may include other fastening means besides the
 locking bolt 134, which fastening means does not include welding the
 counterweights 82 to the support member 78.
 As shown in FIG. 1, three counterweights 82 are placed near one end of the
 support member 78 or side member 46 of the frame 34, and one counterweight
 82 is placed near the opposite end of the support member 78 or side member
 42 of the frame 34, to properly balance the overall weight distribution of
 the hoist assembly 22. If the motor 58 or any other component of the hoist
 assembly needs repairing or replacing which would result in a change in
 the overall weight distribution of the hoist assembly, the counterweights
 82 are simply adjusted, removed or added according to the principles of
 the present invention, thereby properly balancing the modified hoist
 assembly.
 Variations and modifications of the foregoing are within the scope of the
 present invention. For example, the locking device 84 may include a pin
 which extends through the counterweight 82 and the support member 78. It
 is understood that the invention disclosed and defined herein extends to
 all alternative combinations of two or more of the individual features
 mentioned or evident from the text and/or drawings. All of these different
 combinations constitute various alternative aspects of the present
 invention. The embodiments described herein explain the best modes known
 for practicing the invention and will enable others skilled in the art to
 utilize the invention. The claims are to be construed to include
 alternative embodiments to the extent permitted by the prior art.
 Various features of the invention are set forth in the following claims.