Railway rolling stock – Suspended – Inner wheels
Reexamination Certificate
1999-03-09
2001-03-27
Morano, S. Joseph (Department: 3617)
Railway rolling stock
Suspended
Inner wheels
C295S030000, C295S031100
Reexamination Certificate
active
06205930
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to trolley wheels, and more particularly to trolley wheels for an overhead load lifting apparatus such as a monorail hoist. Conventional overhead lifting apparatus such as monorail hoists include trolleys supported by trolley wheels that ride on a rail. Typically, the rail is some variation of an I-beam that includes a substantially horizontal supporting surface with a flat tread supporting surface on which a trolley wheel rolls. To keep the wheel in the proper position on the tread supporting surface, the wheel includes a flange. If the wheel deviates too far from the proper rolling position on the rail, the flange contacts the sidewall of the rail and forces the wheel to move back into the proper rolling position.
While the tread surface of a trolley wheel is often flat, it has been known to crown the tread surface to produce better rolling contact with the supporting surface of the rail. It is also common to linearly taper the flange of the trolley wheel such that only the flange portion nearest the tread surface would ever contact the sidewall of the rail. Examples of these types of trolley wheels are disclosed in U.S. Pat. Nos. 4,236,456 issued to Schreyer et al., 2,997,996 issued to Chapin et al., 2,584,610 issued to Pearson, and 1,367,706 issued to Loudenslager.
It has also been known to use a gradual non-linear tapering on the flange of the trolley wheel. An example of this type of trolley wheel is disclosed in U.S. Pat. No. 1,869,422 issued to Harris.
SUMMARY OF THE INVENTION
Improper and premature trolley wheel wear is a common problem in many monorail hoist systems. Systems that utIlize a wheel with a flat tread surface rolling on a flat supporting surface often encounter various problems created by a mismatch at the rolling interface. Small variations in the surfaces themselves often cause the wheel to wear unevenly due to mismatched contact between the rail supporting surface and the usually softer wheel tread surface. Interface mismatches are also caused by the forces exerted on the trolley that cantilever the wheel off-center, causing the harder rail to dig into the wheel's tread surface.
This common problem can be alleviated by crowning the wheel's tread surface. Mismatches at the rolling interface are significantly or totally eliminated since the crown reduces the surface areas actually in contact. Variations in the surfaces and cantilevering actions of the wheel do not cause uneven or premature wearing. Crowning the wheel's tread surface will allow the wheel to track and fit itself to the rail as it is being used.
A second common problem associated with the trolley wheels of monorail hoists occurs when the sidewall of the rail comes into excessive contact with the flange. Whether the wheel's tread surface is flat or crowned, forces on the trolley cantilever the wheel such that the sidewall of the rail, and especially the corner where the flat supporting surface meets the sidewall, rubs against or digs into the flange. Ideally, a flange should quickly realign the wheel and stabilize it back into the proper position on the rail. Unfortunately, common tapered flanges achieve this objective only after the rail digs into the flange, or the taper causes the wheel to first “ride-up” on the rail. This excessive contact, often known as “scrubbing,” usually occurs at the point on the flange nearest to the wheel's tread surface.
To alleviate these problems, the present invention provides a heat treated trolley wheel having both a crowned tread surface that prevents uneven and premature wear, and a non-tapered flange that prohibits the rail from digging into the flange and also prohibits the wheel from riding-up on the rail. The flange design incorporates an undercut directly adjacent the wheel's tread surface that prevents the corner of the rail from contacting the flange. The flange design also incorporates a “kick-back” feature; a substantially crowned realigning portion that prevents the wheel from riding-up on the rail. This flange design is extremely effective in realigning the trolley wheel on the rail with minimal scrubbing.
Specifically, the invention provides a trolley wheel for a load lifting apparatus movable along a rail having a horizontal supporting surface. The wheel includes a tread surface for rolling contact with the rail and a flange for stabilizing the tread surface in position on the rail. The flange includes either a substantially crowned realigning portion for realigning the wheel to its proper rolling position with minimal contact, or an undercut adjacent the tread surface for minimizing contact between the rail and flange, or both.
Preferably, the tread surface of the wheel is crowned, and the radius of curvature of the crowned realigning portion is less than the radius of curvature of the crowned tread surface. Furthermore, the crowned tread surface, crowned realigning portion, and undercut may all be heat treated, preferably to 450 BHN, for improved toughness and wear resistance.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings.
REFERENCES:
patent: 1218489 (1917-03-01), Stuart
patent: 1367706 (1921-02-01), Loudenslager
patent: 1446463 (1923-02-01), Hoffman
patent: 1811203 (1931-06-01), Laughlin
patent: 1869422 (1932-08-01), Harris
patent: 2584610 (1952-02-01), Pearson
patent: 2861850 (1958-11-01), Nyblom
patent: 2958743 (1960-11-01), Moore
patent: 2997966 (1961-08-01), Chapin et al.
patent: 3107115 (1963-10-01), Kastner
patent: 3753789 (1973-08-01), Kucera et al.
patent: 4230043 (1980-10-01), Aldington
patent: 4236456 (1980-12-01), Schreyer et al.
patent: 4480157 (1984-10-01), Ishikura et al.
patent: 5138560 (1992-08-01), Lanfer et al.
patent: 5662311 (1997-09-01), Waedekin et al.
patent: 5899516 (1999-05-01), Fujimura et al.
Morano S. Joseph
Olson Lars A.
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