Railways – Traction – Cable
Reexamination Certificate
1998-07-14
2001-05-29
Le, Mark T. (Department: 3617)
Railways
Traction
Cable
C104S178000, C104S183000, C104S230000, C104S232000, C254S333000, C254S374000
Reexamination Certificate
active
06237502
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to sheave arrangements and, more specifically, to sheave arrangements that are suitable for use in a slack pulling carriage (SPC).
BACKGROUND OF THE INVENTION
Sheaves and the like are known in the art and may be used to alter the direction of force and/or provide drive to a line, amongst other purposes.
When sheaves are used in a line driving application, there is a constant challenge to achieve desired friction between the drive sheave (often referred to as the “drum”) and the line, while not causing undue wear in the sheave or line. Slippage of the line within the sheave results in the consumption of additional energy, wear of components and an increase in fire potential due to sparking, etc.
Known sheave arrangements for slack pulling carriages include those that have a generally U-shaped circumferential groove that approximates the diameter of a line to be used therein and a plurality of weld beads at the bottom or sides of the groove. The weld beads improve friction (or traction) between the drum and the line (like studs on a studded snow tire), but induce wear in the line and sheave at a disadvantageously rapid rate. The undesirable rate of line wear is not only economically disadvantageous in that the line and/or sheave must be replaced, but also raises significant safety concerns.
A need thus exists for a sheave arrangement that provides desired friction without unreasonable wear. This need exists in many driving sheave applications, including but not limited to, slack pulling carriages and related equipment.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a sheave arrangement for a SPC that achieves desired friction without undesirably inducing wear in a line associated therewith.
It is another object of the present invention to provide such a sheave arrangement that includes a drum and complementary tension wheel.
It is also an object of the present invention to provide a SPC drive sheave arrangement that includes a singular drum that accommodates lines of different size.
These and related objects of the present invention are achieved by use of a sheave arrangement suitable for a slack pulling carriage as disclosed herein.
In one embodiment, the present invention comprises a slack pulling carriage that includes a frame; a drum having a circumferential groove coupled to said frame; a tension wheel provided opposite said drum; and a motor for driving said drum; wherein said groove includes first and second interior side walls and at least a portion of each of said side walls is substantially straight and disposed at an angle, alpha, of approximately 5-100 degrees from the other side wall. A tension wheel is preferably provided opposite the driving drum. At least a portion of the tension wheel and a portion of each of the interior side walls of the drum are preferably configured to apply a substantially non-distorting driving force on a line provided between said drum and said tension wheel. In a further preferred embodiment, the tension wheel and interior side walls of the drum respectively contact a line to be driven at three locations, substantially equilaterally spaced.
In another embodiment, the present invention includes a method of driving a line with such a sheave arrangement.
The attainment of the foregoing and related advantages and features of the invention should be more readily apparent to those skilled in the art, after review of the following more detailed description of the invention taken together with the drawings.
REFERENCES:
patent: 2359073 (1944-09-01), Allard
patent: 2919015 (1959-12-01), Turecheck
patent: 4005852 (1977-02-01), Schmitmeyer et al.
patent: 4706940 (1987-11-01), Harig
patent: 5020443 (1991-06-01), Gauthier
patent: 5129626 (1992-07-01), Koludzki
patent: 5975319 (1999-11-01), Carlile
Adamson Steven J.
Le Mark T.
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