Various embodiments described herein relate to a lifting or locking system and a method.
Lifting systems are needed for many applications. Outdoorsmen frequently use lifting systems. Hunters lift deer and other big game as part of the butchering process. Campers that camp in areas with bears, hoist a bear bag with all their smellables from a high branch on a tree. This prevents bears from coming into camp. There are other uses of lifting systems such as for hoisting bikes or canoes up to the ceiling of a garage for storage purposes. These are but a few example uses.
Currently, ropes must be tied off while the heavy load is held up. For example, when hoisting a bear bag, the rope is wrapped around the tree to slow or prevent slippage. The rope is then tied off to another tree while still being held taut. It is difficult to hold a rope taut while tying it off. If the job is not done correctly, there are consequences. The load or object being hoisted may come crashing down which endangers others and which can damage the object being hoisted.
The invention includes a lifting or locking mechanism that includes a housing, an axle attached to the housing, and an element including a cam surface mounted for rotation on the axle. The distance between the cam surface and the housing changes between a maximum clearance distance and a minimum clearance distance as the element rotates about the axle. The lifting or locking mechanism also includes a line which can be moved between a first position over the cam surface and a second position. In one embodiment, the cam surface includes a surface treatment for increasing an amount of friction at the cam surface. In another embodiment, the cam surface is associated with a cam and in still another embodiment, the cam surface is associated with a round element that includes an off center opening. The round element is rotatably mounted to the axis via the off center opening. In still a further embodiment, the lifting mechanism also includes a sheave mounted to the axle. The cam surface and the sheave can be formed from a single piece of material. The cam surface and the sheave can also be separate elements. In one embodiment, the line is in the second position when it is positioned within the sheave. The lifting or locking mechanism, in one embodiment, is made from a metal.
The fixed block 200 also includes a set of pulleys 211, 212 which are rotatably mounted to an axle 214. The axle 214 is attached to a fixed block housing 220. The pulley 212 includes a widened edge 216 which, when assembled, is placed close to the side of the fixed block housing 220. In the embodiment shown, the widened edge 216 of the pulley or sheave 212 is knurled so as to provide additional friction on the widened edge 216. The fixed block housing 220 is slightly wider than the moving block housing 120 so as to accommodate the widened edge 216 of the pulley 212. The fixed block housing 220 also has an attachment point 230. A carbineer 232 is attached to the fixed block attachment point. One end of a line 150 is attached to the fixed block housing 120. The line is threaded though the pulley 111, the pulley 211, the pulley 112, and the pulley 212. A free end of the line 150 leaves the pulley or sheave 212. A pulling force can be placed on the line 150 so as to move the moving block 110 with respect to the fixed block 200. The line 150 substantially completes the block and tackle 110.
The pulley 212 or set of pulleys 211, 212 in the above block and tackle 100 are modified. The pulley 212 includes the widened edge 216 with the knurled portion 216.
When the pulleys 211, 212 are offset the motion corresponds to a simple harmonic motion that is related to the offset of the pulleys 211, 212 from rotation about the center of the pulley 212 or pulleys 211, 212. As the pulley rotates it passes a maximum clearance distance, Cmax, and a minimum clearance distance Cmin, between the pulley 212 or pulleys 211, 212 and the housing 200. The cord or line 150 has a diameter, d, which is larger than the minimum clearance distance Cmin.
In one embodiment, the sheaves or pulleys 211, 212 are both off center while the sheaves or pulleys 111, 112 are centered. In still another embodiment, the sheaves or pulleys 111, 112, 211 are all centered and the sheave 212 is off center. When the sheave 212 is off center, the sheave produces an eccentric motion like a cam.
The surface 542 associated with the outer perimeter of the cam 540 can also be treated to increase friction, such as by knurling the surface. The surface 542 can also be treated in other ways to roughen the surface 542 which in turns enhances the gripping ability of the cam 540. The cam 540 can be made of metal or another material. The block and tackle 500 is completed by attaching a line 550 to the fixed block 520 or the moving block 510 and threading the line 550 through the sheave 511, sheave 521, sheave 512 and sheave 522. The free end of the line can be pulled to move a load attached to the moving block 510.
During operation, the cord or line 550 is used to hoist a load as it would be in a block and tackle, such as block and tackle 500. When the load is at a desired position the user merely moves the cord or line to the side of the sheave or pulley 522 to a position crossing the outer surface 542 of the cam 540. The load is then released or let down slightly with the cord or line 550. The cord or line 550 has a diameter which is larger than the minimum distance between the lobe 541 of the cam 540 and the fixed housing 523 so the cord is caught or pinched between the housing 523 of the fixed block 520 and the edge 542 at the outer perimeter of the cam 540. The knurling on the widened edge 542 increases the friction between the cord or line 550 and the edge 542. The cam 540 has a thickness to allow the edge 542 to pinch or grip the line 550. This prevents or substantially curtails the cord or line 550 from slipping over the edge 542. When the cam 540 approaches the minimum clearance point (corresponding to the lobe 541 passing the housing 523) as it rotates, the line 550 is captured between the cam 540 edge 542 and the housing 523. Adding more weight to the load on the moving block 510 results in increased wedging of the line or cord 550 into the space between the surface 542 of the cam 540 and the housing 523. When pinched, the load is held in position by the line 550. The line 550 does not move since it is wedged between the 542 and the housing 523. To release the load, the line 550 is pulled in the other direction away from the edge 542 of the cam 540 and toward the sheave 522. The free end of the line 550 is pulled and the line 550 is dislodged and repositioned in the sheave or pulley 522. The block and tackle 500 can then be used to move the load.
In another embodiment, the cam 540 can be replaced with a disk having a opening therein that is off center so that it presents an eccentric motion as it rotates. The perimeter of the disk can be roughened or treated to increase friction. The disk can be attached to sheave 522 or attached to the shaft 524 as discussed above. In short, the eccentric disk would replace the cam 540 with its lobe 541. It could be attached to the shaft or axle 524 in any way, including the ways mentioned above with respect to the cam 540.
The surface 843 associated with the outer perimeter of the cam 840 can also be treated to increase friction, such as by knurling the surface. The surface 843 can also be treated in other ways to roughen the surface 543 which in turns enhances the gripping ability of the cam 840. The cam 840 can be made of metal or another material. The block and tackle 800 is completed by attaching a line 850 to the fixed block 520 or the moving block 510 and threading the line 850 through the sheave 511, sheave 521, sheave 512 and sheave 522. The free end of the line can be pulled to move a load attached to the moving block 510.
In operation, the line 850 could catch or be pinched near or at lobe 841 or near or at lobe 842. When the cam is bigger in diameter for heavy duty operation, the line will catch or be pinched within half a rotation. The more lobes in the multi-lobed cam, the less movement needed before the line will catch. Of course, the number of lobes needs to be balanced with the diameter of the cam 840. At some point, the number of lobes becomes too numerous such that the line 850 can not be moved to a position on the cam surface 843 without being hindered by another lobe.
It should be noted that the number of sheaves is not limited to two sheaves in the fixed block and two sheaves in the moving block. By increasing the sheaves, the amount of mechanical advantage is increased. More line is needed with an increased number of sheaves in the fixed block or the moving block.
It should also be noted that the invention is not required to be used as a block and tackle.
In summary, a block and tackle includes a housing for one of a fixed block and a moving block, an axle attached to the housing, and a sheave. The sheave includes a widened edge. The sheave has an opening therein which is off center so that the clearance distance between the edge of the sheave and the housing varies as the sheave rotates. The sheave is rotatably attached to the axle. A line passes over the sheave. The line has a free end. The line has a diameter that is larger than the minimum clearance distance between the edge of the sheave and the housing. The line is movable between a first position in the sheave and a second position over the widened edge of the sheave. In one embodiment, the sheave and the widened edge are formed from a single piece of material. The material can be metal or any other suitable material for a particular application as a block and tackle. In some embodiments, the widened edge is provided with a surface treatment to increase friction. The surface treatment in one embodiment includes knurling. The line has a diameter which is slightly less than a distance across the sheave. In one embodiment, the axle is placed at a distance from the top of the housing such that the minimum clearance between the widened edge and the housing is small enough to prevent the movement of the widened edge and the sheave when the line is placed on the widened edge. The movement is prevented when the clearance is at or near the minimum clearance distance. Movement of the sheave is not prevented at all points where the line is placed on the widened edge.
The invention also contemplates a pulley includes a housing, an axle attached to the housing, and a sheave. The sheave further includes a widened edge. The sheave has an opening therein which is off center so that the clearance distance between the edge of the sheave and the housing varies as the sheave rotates. The sheave is rotatably attached to the axle. The pulley also includes a line passing over the sheave. The line has a free end. The line has a diameter that is larger than the minimum clearance distance between the edge of the sheave and the housing. The line is movable between a first position in the sheave and a second position over the widened edge of the sheave. In one embodiment, the sheave and the widened edge are formed from a single piece of material. The material can be metal or any other suitable material for a particular application as a block and tackle. In some embodiments, the widened edge is provided with a surface treatment to increase friction. The surface treatment in one embodiment includes knurling. The line has a diameter which is slightly less than a distance across the sheave. In one embodiment, the axle is placed at a distance from the top of the housing such that the minimum clearance between the widened edge and the housing is small enough to prevent the movement of the widened edge and the sheave when the line is placed on the widened edge. The movement is prevented when the clearance is at or near the minimum clearance distance. Movement of the sheave is not prevented at all points where the line is placed on the widened edge.
The invention also includes a lifting mechanism that includes a housing, an axle attached to the housing, and an element including a cam surface mounted for rotation on the axle. The distance between the cam surface and the housing changes between a maximum clearance distance and a minimum clearance distance as the element rotates about the axle. The lifting mechanism also includes a line which can be moved between a first position over the cam surface and a second position. In one embodiment, the cam surface includes a surface treatment for increasing an amount of friction at the cam surface. In another embodiment, the cam surface is associated with a cam and in still another embodiment, the cam surface is associated with a round element that includes an off center opening. The round element is rotatably mounted to the axis via the off center opening. In still a further embodiment, the lifting mechanism also includes a sheave mounted to the axle. The cam surface and the sheave can be formed from a single piece of material. The cam surface and the sheave can also be separate elements. In one embodiment, the line is in the second position when it is positioned within the sheave. The lifting mechanism, in one embodiment, is made from a metal.
The lifting mechanisms discussed above all operate in much the same manner. Namely, the line is used to lift or move a load. The line can be moved to a cam surface which can be a cam or a round surface mounted off center. The line is released to lower the load and when the line is on the cam surface it catches or is gripped as the cam surface goes toward the position with respect to the housing where the clearance distance is minimum. The load can be held without having to tie off the free end of the line. Of course, some users are cautious and would also tie off the line. The line can be release by tugging or applying a force to the line to lift or move the load. The line is moved to a second position off the camming surface. In some embodiments, this is a position within a sheave. When in the sheave, the lifting mechanism can be operated without the line catching or interfering with the housing. The lifting mechanism can be a block and tackle or can be a pulley.
The same mechanism can be used in situations where there is a substantial horizontal component of force to overcome. In these situations, the mechanism will lock a rope, line or cord in place even though the force may include a substantial portion which is not due to gravity. The mechanism can therefore be termed a locking mechanism which can be used to overcome the force of gravity or other forces that include a substantial horizontal component. The locking mechanism can hold a rope, line or cord when any force is present resulting in tension on the line, rope or cord. The tension force can be due to gravity, another vertical force, or a horizontal force, or a mixture of vertical and horizontal forces. The locking mechanism will hold the line, rope or cord in each instance. The locking mechanism includes a housing and an axle attached to the housing, and a sheave that is attached to the axle so that the sheave rotates with respect to the housing. The sheave has a widened edge. In one embodiment, the sheave has an opening therein which is off center so that a clearance distance between the edge of the sheave and the housing varies between a minimum and maximum clearance distance as the sheave rotates. The locking mechanism also includes a line. The line has a diameter that is smaller than the maximum clearance distance and larger than the minimum clearance distance. The line passes over the sheave. The line is movable between a first position in the sheave and a second position over the widened edge of the sheave. The line is brought into a locking position as tension is applied to one end of the line when the line is brought into the second position. After line is brought to a second position over the widened portion of the sheave, the counterforce on the line is released allowing the line to be pinched or gripped between the widened edge and the housing. Releasing the line is accomplished by pulling the free end to move the pulley or sheave in a direction away from the housing. The line can then be moved onto the sheave and the locking mechanism can be used as a pulley alone or as part of a block and tackle. The widened edge can be provided with a surface treatment to roughen the surface and increase the friction between the line and the widened edge. In another embodiment, the housing portion that grips or pinches the rope can also be provided with features or a surface treatment for increasing the friction on the line. In one embodiment, both the housing and the widened edge are provided with a surface treatment. One surface treatment can include knurling. In another embodiment, one or both of the housing and the widened edge can be provided with features, such as ridges, for enhancing the ability of the widened edge or housing to grip the line. In some embodiments, these could be cast or machined into the housing or widened edge. In other embodiments, one of the housing or the widened edge is provided with a first surface treatment and the other is provided with a second surface treatment or set of features.
As discussed above, the sheave is provided with an opening that receives an axle.
The lifting mechanism or locking mechanism has wide application. This can be used by outdoorsman to hoist big game, or by a homeowner wanting to store items near the ceiling of a garage. These are but two examples. The number of uses is seemingly endless. This device is especially helpful to a weaker user who would have trouble tying off a free end of a line while maintaining tension in the free end. Other uses include: a flower pot hanger, a rifle and bow hoist. a tree stand hoist, an RV (recreational vehicle) tie-down, an aircraft tie-down, an extension ladder assembly, an automatic big game feeder (to raise and lower the feeder), a birdhouse (raising and lowering), sailboat rigging, a boat anchor, a venetian blind, a painter/window washer hoist, a backpack tie-down, rock climbing gear, a tarp tie-down, a camping tent tie-down, and for farm gear, such as for barb wire fence stretcher. Of course, this list is not exhaustive as there are many more uses for the lifting mechanism or locking mechanism discussed in detail above.
This has been a detailed description of some exemplary embodiments of the invention(s) contained within the disclosed subject matter. Such invention(s) may be referred to, individually and/or collectively, herein by the term “invention” merely for convenience and without intending to limit the scope of this application to any single invention or inventive concept if more than one is in fact disclosed. The detailed description refers to the accompanying drawings that form a part hereof and which shows by way of illustration, but not of limitation, some specific embodiments of the invention, including a preferred embodiment. These embodiments are described in sufficient detail to enable those of ordinary skill in the art to understand and implement the inventive subject matter. Other embodiments may be utilized and changes may be made without departing from the scope of the inventive subject matter. Thus, although specific embodiments have been illustrated and described herein, any arrangement calculated to achieve the same purpose may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all adaptations or variations of various embodiments. Combinations of the above embodiments, and other embodiments not specifically described herein, will be apparent to those of skill in the art upon reviewing the above description.
This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/525,554, filed on 19 Aug. 2011, which is incorporated by reference herein.
Number | Date | Country | |
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61525554 | Aug 2011 | US |