1) Field of the Invention
The invention relates generally to a winch, and more particularly to a side-threading winch which can be quickly affixed to a choke strap, and tightening the same.
2) Prior Art
Choke straps are used by crane operators and the like to attach the crane hook to the object to be lifted. During lifting, the object has a desired orientation. The desired orientation is dependent on a number of possible considerations, including, but not limited to: the size of the space through which the object is to be moved, whether the object being lifted is to be connected to another device having a precise orientation, the levelness of the object being lifted (i.e. a pallet loaded with multiple objects that are only partially secured), and the effectiveness of the choke during the lift. If the orientation is wrong, the choke strap may not be secured, causing the choke to shift and the object being lifted to sift further or fall. The proper positioning and the effective length of the choke straps determines whether the desired orientation is achieved. To confirm that in fact the choke straps are properly positioned the crane operator will usually lift the object only slightly off its supporting surface, thereby confirming that none of the straps are slack, and that the object has the proper orientation. If a strap is slack or the orientation is wrong then a strap is not carrying the desired proportion of the load. Also, a slack choke strap is an indication that the center of gravity is off-line of the lifting force, and a disproportionate weight will be placed one or more of the other choke straps. To correct loose strap(s) and the orientation, the crane operator sets the object back down on its supporting surface, and the choke strap(s) is adjusted. The adjustment is usually made by either repositioning its choke position on the object, by adding another wrap to the strap, by using a shorter choke strap or by a combination thereof. The adjustment process to remove the slack is time consuming, and often has to be repeated numerous times because it is largely one of an educated guess. The problem is especially difficult to correct when the object has a complex asymmetrical shape.
What is needed a means whereby the slack can be quickly taken out of the choke strap with out either repositioning the strap, adding another wrap to the strap or changing to a shorter length strap. A possible solution is to attach the choke strap to a come-along. As a practical matter the addition of a come-along to the strap cures one problem, but causes another. The come along adds length to the choke strap, and accordingly shorter strap must be used to accommodate for the length of the come-along. The come-along adds weight, and if multiple choke straps are fitted with come-alongs, then the overall usable lifting force is lowered. Most come-alongs have a handle which can become entangled with the other straps. Since, it is not known in advance which strap will need to be adjusted, one could potentially pre-fit each strap with a come-along. The addition of multiple come-alongs also costs, increases the possibility for mechanical failure and therefore poses a safety problem. Another possible solution to removing the slack is to attach an end of the strap to a conventional strap winch. Similar problems are encountered, plus a conventional strap winch requires end on threading. What is further needed is a means of adjusting the strap that does not require the strap to be changed, does not disconnect from either the object or the crane hook, does not add length to the strap, and does not require end on threading.
The invention is a device which enables the effective length of a strap, and in particular a choke strap already attached, to be quickly adjusted. Choke straps can be of any width, but are typically 2, 3, 4, 6, and 8 inches wide and xc2xc inch thick. The choice of the appropriate strap is largely dependent on the weight of the object being lifted. At least two, and often three or more straps are employed to give the object proper orientation when lifted. The invention is a device that can be attached to a choke strap without disconnecting the strap, a device that does not require end on threading, a device that does not add length to the strap, and a device that does not interrupt the continuity of the strap. In the scenario described in the Background of the Invention, when the crane operator lifts the object slightly off the supporting surface, and finds that a strap is loose, the invention can be fitted onto the choke strap, and the strap can be shorten to the needed effective length. The choke strap need not be repositioned, changed or wrapped. The choke strap is left attached to the object and the crane hook. The invention is a side-threading winch, wherein in contrast to a conventional winch where the strap is threaded from an end of the strap, the strap is threaded along a longitudinal edge. The invention can also be end threaded like a conventional winch. The quick adjusting choke winch is appropriately sized so that multiple width straps can be accommodated. For instance, one size quick adjusting choke winch can accommodate a 2, 3 and 4 inch wide strap. The quick adjusting choke winch is comprised of: a base plate having a bearing; an open-ended split-center shaft; at least two pack rollers for controlling the tangential angle of the strap being wound; a means for guiding the strap within the winch; a ratchet plate; a releasable main pawl, main pintle and main torsion spring; a releasable safety pawl safety pintle and safety torsion spring; a means for turning the open-ended split-center shaft; a cover plate; and at least one fastening element for attaching the cover plate. The ratchet plate is co-axially affixed to the open-ended split-center shaft, so that when the ratchet turns the open-ended split-center shaft turns through the same rotation. The ratchet plate is mounted proximal to the base plate, but preferably not in contact with the base plate. Mounted on the same side of the plate are an end of the open-ended split-center shaft, an end of the at least two pack rollers, the means for guiding the strap, an end of the main pintle, and an end of the safety pintle. The cover plate is removably mounted to at least the pack rollers, and receives the open-end of the split-center shaft. The split-center of the open-ended split-center shaft has an opening that is sufficiently wide to receive the thickness of the strap. This thickness is commonly between xe2x85x9 and xc2xd of an inch, with the most common thickness being xc2xc of an inch. It is understood that larger or smaller variations of the invention are anticipated, and do not fall outside the scope of the invention. The at least two pack rollers, the means for guiding the strap, and the open-ended split-center shaft, like wise, have a sufficient length to wind the width of the choke strap. The diameter of the open-ended split-center shaft and the diameter of the ratchet determine the length of strap that can be wound. For instance if the strap material is 0.25 inches, then a 1.0 inch diameter open-ended split-center shaft and 5.0 inch ratchet can hold 6.25 feet. Increasing the shaft to 1.5 inches reduces the length to 6 feet, and increasing the ratchet diameter to 6 inches allows 8.8 feet to be wound. The means for turning the open-ended split-center shaft is a handle or a powered wrench or both. If the means for turning the open-ended split-center shaft is a handle, then the handle is preferably removable, like a socket wrench. If the means is a powered wrench, then a lug wrenches, such as pneumatic or electric wrench, is preferred. Hydraulic wrenches are also anticipated. Many wrenches now, like lug wrenches, are available as either powered or manual.
The means for guiding the strap comprises a first pair of rollers and a second pair of rollers, wherein an end of each of the rollers is mounted on the base plate such that the rollers of the first pair of are separated by a distance slightly wider than the thickness of the strap, and the rollers of the second pair of are similarly separated, and such that the first pair of rollers guides the strap on one side of the open-ended split-center shaft, and the second pair of rollers guides another portion of the strap on another side of open-ended split-center shaft. An end of each roller of the first pair and an end of each roller of the second pair of rollers are mounted on the base plate such that the rollers are distal to the open-ended split-center shaft. The means for guiding the strap further comprises a first backlash roller and a second backlash roller, where an end of the first backlash roller is mounted radial to the open-ended split-center shaft and outside of a normal thread path, and where, on another side of open-ended split-center shaft, an end of the second backlash roller is mounted radial to the open-ended split-center shaft and outside of a normal thread path. The cover plate comprises apertures for receiving an opposing end of the rollers of the first pair, the first backlash roller and the second backlash roller.
The fastening elements for attaching the cover plate are one or more elements selected from the group consisting of quick connecting pins, nuts, cap nuts, wing nuts, cotter pins, ring pins, snap rings, rivets, snaps, spring loaded cams, and the like. The preferred choice of element can be optimized so that for instance a powered wrench or electric screwdriver can be used to attach the fastening elements.
The releasable main pawl of the quick adjusting choke winch is comprised of an elongated pawl, a control arm and a hub, where the control arm has a length that is sufficient to easily apply thumb pressure to disengage the pawl, and where the length is short enough so as to not project beyond an orthogonal plane defined by a perimeter edge of the base plate. The releasable main pawl has a locking mechanism by which the releasable main pawl can be disengaged from the ratchet. The locking mechanism is preferably a thumb switch which shifts a rod such that when the control arm is first depressed, the control arm is restrained by the rod. Alternatively, the locking mechanism can merely be a projection emanating from the base plate, such when the control arm is depressed it slides over the projection. Also, the locking mechanism can be a cam which moves the torsion spring such that torsional force is no longer applied to the main pawl. There is a second pawl, which is a releasable safety pawl. The safety pawl comprises an elongated safety pawl, a safety control arm, and a safety hub. The safety control arm has a length and leverage that is sufficient to easily apply thumb pressure to disengage the pawl, and where the length is short enough so as to not project beyond an orthogonal plane defined by a perimeter edge of the base plate. When the locking mechanism is engaged and simultaneously the safety control arm is depressed, then the open-ended split-center shaft and ratchet can rotate freely. Otherwise, the ratchet is always locked. It is anticipated that additional safety locks can be incorporated into the invention. When a socket wrench type handle is employed the ratcheting action of the handle can be set so that even when the open-ended split-center shaft and ratchet are free to rotate, the handle does not.
The various rollers of the quick adjusting choke winch are comprised of at least one sleeve which rotates on a roller shaft, wherein the roller shaft has an smaller diameter axial end for mounting to the base plate, and a smaller axial opposing end for affixing the cover plate to the roller.
The open-ended split-center shaft comprises a larger two lobe winding drum, wherein the lobes are separated by a distance that is greater than the thickness of the strap, a substantially solid section to which the ratchet attaches, a smaller axial end comprised of a journal and bushing for retaining the journal, and a machined end for connecting to the handle. Optionally, the two lobe winding drum further comprises a secondary journal and a secondary bushing, wherein the secondary bushing is fitted with a secondary collar. The cover plate further comprises a secondary bearing for receiving the open-ended split-center shaft. The bushing of the primary journal is fitted with a collar or some other suitable restraining/centering mechanism to prevent the open-ended split-center shaft from drifting.
The quick adjusting choke is side-threaded by temporarily removing the cover plate, or end threaded like a convention winch.