Handling: hand and hoist-line implements – Contact lens applicator
Reexamination Certificate
1999-06-23
2001-03-13
Kramer, Dean J. (Department: 3652)
Handling: hand and hoist-line implements
Contact lens applicator
C294S089000, C403S078000, C403S164000
Reexamination Certificate
active
06199925
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates in general to hoist ring assemblies and, in particular, to a high load capacity hoist ring assembly capable of being installed at a required tensile value to an object to be lifted without the use of either a torque multiplier or a hydraulic tensioning device.
2. Description of the Prior Art
Various high load hoist ring assemblies have been proposed previously. For Example, in Tsui et al U.S. Pat. No. 5,848,815, a safety hoist ring was proposed for lifting large loads. However, for a given hoist load capacity rating, the mount stud or shank member of the hoist ring assembly must be torqued to a predetermined value in order to pre-stress that member to the required tensile value. In order to properly pre-stress the shank member, the required tensile value should at least be equal the load capacity rating of the assembly, however, it is preferable that it be at least 1.5 times greater to assure against misuse, such as overloading the assembly, and the like. As the load capacity of the hoist ring assembly is increased, so to is the torque value required to achieve the proper tensile value in the shank member. For instance, a hoist ring assembly of the configuration disclosed in Tsui et al U.S. Pat. No. 5,848,815 having a load capacity rating of 50,000 pounds (lbs.), weighs about 87.5 lbs, and requires a torque value of 2,100 ft-lbs in order to achieve the required tensile value of 75,000 lbs in a shank member having 2½″-4 UNC threads. When the assembly is increased to a load capacity rating of 100,000 lbs, the assembly weighs 240 lbs, and requires a torque value of 6,800 ft-lbs in order to achieve a required tensile value of 150,000 lbs in a shank member having 3½″-4 UNC threads. These extreme torque values are impossible to achieve manually with conventional torque wrenches. Expensive torque multipliers or hydraulic tensioning devices are required. For instance, to achieve the torque value of 6,800 ft-lbs in the example above, a conventional torque wrench having a 3 foot moment arm would require the application of 2,266 pounds of pulling force to the wrench by the operator. Thus, as those skilled in the art recognize, the only practical method known to achieve these torque values requires the use of a torque multiplier in combination with a conventional torque wrench, or the use of a hydraulic tensioning device. Undesirably, such devices are expensive, often being twenty times as much, or more, than the cost of the hoist ring assembly itself. In addition, these devices are both heavy and bulky and thereby reduce the range of possible mounting locations for the hoist ring assembly.
It has been found that these problems arise when the desired torque requirements reach about 230 ft-lbs and above. This nominal torque value, 230 ft-lbs, is required when load capacity ratings of the hoist ring assemblies reach around 10,000 lbs.
Those concerned with these problems recognize the need for an improved high load capacity hoist ring assembly capable of being installed to the surface of an object to be lifted at its required tensile value without the use of a torque multiplier or hydraulic tensioning device.
These and other difficulties of the prior art have been overcome according to the present invention.
BRIEF SUMMARY OF THE INVENTION
It is one object of the present invention to provide a high load capacity hoist ring assembly that can be securely fastened to an object to be lifted at its required tensile value without the use of a torque multiplier or hydraulic tensioning device.
It is another object of the present invention to provide a high load capacity hoist ring assembly having a greater range of possible mounting locations on an object to be lifted.
A preferred embodiment of the high load capacity hoist ring assembly according to the present invention comprises a shank member, a compression member, a retainer flange, and a lifting loop captively engaged between the shank member and retainer flange for rotational and pivotal movement. The hoist ring has a transversely disposed pivot structure allowing the ring to swivel throughout 360 degrees and pivot approximately about 180 degrees thereto. Uniquely, the retainer flange has a plurality of threaded holes at spaced apart locations about an outer peripheral that is spaced from the longitudinal axis of the assembly. The holes extend through the retainer flange generally parallel to but spaced from the longitudinal axis of the assembly. The threaded holes are adapted to receive a plurality of bolts threadably engaging the holes and extending through the retainer flange. The bolts have jack ends that extend from the holes in the retainer flange to compressively bias the compression member upon installation of the assembly. Each bolt is adapted to separately receive a torque, and once received, the bolts in the aggregate achieve the required tensile value in the shank member without the need of a torque multiplier or hydraulic tensioning device. The bolts are simply individually torqued, preferably in a star pattern to an easily achievable value by manual operation of a convention torque wrench. There is no need to use a torque multiplier or hydraulic tensioning device to reach the desired torque values with the individual bolts. The effect of the torque applied to the individual bolts is, however, additive in generating the desired tension in the shank member.
Other objects, advantages, and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.
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CBC Industries, Inc.
Jagger Bruce A.
Kramer Dean J.
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