Patent Application
20110240791
This invention relates to strap spools mountable to drive shafts in various strap winding apparatus, such as winches and torsion spring counterbalances.
Nylon webbing has begun to replace wire cable in a variety of mechanical winding apparatus. For example, certain winches, ramp door lifts, and over head door torsion spring counterbalances have been developed that use lengths of nylon webbing in place of wire cable. While webbing is replacing the traditional wire cable, conventional winding apparatus still wind the lengths of webbing onto single-piece cast or molded drums as with the wire cable.
The strap spool of this invention has a two piece design where two symmetrical spool halves slidably mate to form a drum around which the strap is wound. Each spool half has a central hub with an axial opening, which allows the spool halves to mount onto a drive shaft. An annular flange extending radially around the hub and a barrel sleeve extending from the hub perpendicular to the flange. When spool halves are mated together on a drive shaft, the barrel sleeves slidably extend into axial openings in the hub of the opposite spool half and form a tubular drum overlying the drive shaft around which the strap is wound. The strap spool's two piece design and the slidable engagement of the two mating spool halves allows the strap spool to accommodate straps of various widths. The two-piece design also enables convenient strap installation and replacement without additional fasteners, ties or tools.
Theses and other advantages of the present invention will become apparent from the following description of an embodiment of the invention with reference to the accompanying drawings.
The drawings illustrate an embodiment of the present invention, in which:
Referring now to the drawings,
As shown, each half 20 and 20′ has a central hub 30, an integral annular flange 40 extending radially around the hub, and an integral barrel sleeve 50 extending axially from the hub perpendicular to the flange. Hubs 30 have an axial opening 31, which allows the spool halves 20 and 20′ to mount onto a drive shaft. When halves 20 and 20′ are mated together on a drive shaft (
As shown, barrel sleeves 50 have a convex outer surface 52 and a concave inner surface 54. Openings 31 of each hub 30 is defined in part by a first arcuate inner sidewall 32 and a second inner sidewall 34. The radius of second inner wall 34 is greater than the radius of the first inner wall 32, thereby defining a recessed axial channel within which the distal ends of barrel sleeve 35 of the mating spool half 20 and 20′ nests. When mated together, the convex outer surface 52 of barrel sleeve 50 seats against second inner sidewall 34 of hubs 30. In addition, concave inner surface 54 of barrel sleeves 40 share the same inner radius as first inner sidewall 32 of hubs 30 to form the axial bore for receiving drive shaft 2. When mated together, the sides 56 of barrel sleeves 50 abut the flat edges 36 between first inner sidewall 32 and second inner sidewall 34 to prevent the halves from rotating with respect to one another. In addition, barrel sleeve 50 has a longitudinal groove 55 for receiving a raised axial rib 38, which extends radially from second inner wall 34, which further prevents the halves from rotating but also serves as a limit to the axial travel of the halves relative to each other (the axial travel is arrested when rib 38 abuts the end of groove 55).
To facilitate the connection of strap 4 to strap spool 10, strap 4 may terminate in a looped end 6 (
One skilled in the art will note that the strap spool of this invention provides several advantages over conventional single-piece cable and strap drums. The strap spool's two piece design allows the width of the strap drum area to be set by the axially positioning of the two mating spool halves, thereby allowing the strap spool to accommodate straps of varying widths. This adjustment to the drum area width is limited only by the width of the hubs and the length of the groove in the barrel sleeve. The strap spool of this invention can be dimensioned and configured to work with any diameter of drive shaft, as well as for use with any ranges of strap widths. The two-piece design enables conveniently strap installation and replacement without additional fasteners, ties or tools. The configuration of the barrel sleeve having the gap and passage through which the strap is received between the drive shaft and barrel sleeve provides a sure connection between the strap and the strap spool. Replacement of a looped end strap can be accomplished by simply removing the outside spool half. Because each spool half is separately secured to the drive shaft, the inside spool half can remain fixed to the drive shaft while the outside spool half is pulled from the drive shaft and a new looped end strap placed around the drive shaft. In the case of straps using blocked ends, replacement of a strap can be accomplished without physically removing either spool half.
The embodiment of the present invention herein described and illustrated is not intended to be exhaustive or to limit the invention to the precise form disclosed. It is presented to explain the invention so that others skilled in the art might utilize its teachings. The embodiment of the present invention may be modified within the scope of the following claims.
