Apparatus and method for correcting skew of a traveling crane by maximizing friction between leading skewed wheel and the rail

• US 5,216,957 A
• Filed: 12/13/1991
• Issued: 06/08/1993
• Est. Priority Date: 12/13/1991
• Status: Expired due to Term

• Current Assignee: US Bank National Association (US Bancorp)
• Original Assignee: Harnischfeger Corporation (Mitsui & Company Limited)
• Inventors: Thorsen, George E.
• Primary Examiner(s): Oberleitner, Robert J.
• Assistant Examiner(s): MORANO IV, SAMUEL J
• Application Number:
  US07/806,530
• Time in Patent Office: 543 Days
• Field of Search: 105/163.1, 105/163.2
• US Class Current: 105/163.2
• CPC Class Codes: B66C 9/08 Runners; Runner bearings wheels for railbound vehicles B60B
• CPC Class Codes: B66C 9/16 with means for maintaining alignment between wheels and track

Abstract

A skew correcting apparatus for a crane having drive wheels traveling on spaced apart rails which are independently driven. Each one of the drive wheels has an axially extending single diameter cylindrical surface and first and second axially spaced apart radially extending circumferential flanges. The spacing distance of the first flange of each of the first and second wheels is such that, when the crane is in one of the skewed positions the first flange of the leading wheel in the direction of travel engages the faced outer side of the rail head and the engagement of the second flange of the lagging one of the wheels with the inner rail side which it faces is minimized. Each rail head has a shoulder surface including a radius defining a cross-sectional shoulder curvature. The first flange of each one of the wheels also includes a circumferential flange juncture surface adjoining the cylindrical surface. Each flange juncture surface faces a rail head shoulder surface and has a cross-sectional radius such that the flange juncture surface of the leading skewed wheel engages the faced rail head shoulder surface along a cross-sectional line of engagement in each one of the skewed positions. Preferably the radii of the rail head shoulder surface and flange juncture surface are substantially equal so that friction is maximized.

Claims

1. In a traveling crane supported on a pair of spaced apart generally parallel rails and including a frame spanning the space between the rails, a truck attached to the frame adjacent each rail, at least one wheel rotatably mounted on each truck in engagement with one of the rails for movement at a linear speed in the direction of the parallel rails whereby the crane travels along and in a position parallel to the rails, the crane also having two oppositely skewed positions while traveling on the rials such that one of the first and second wheels is a leading wheel and the other wheel is a lagging wheel in each of the skewed positions in the direction of travel of the crane, and driving means for rotating a first wheel on one of the trucks and a second wheel on the other of the trucks independently of each other, the combination comprising:

a rail head on each rail, each rail head having a top side, an inner side, an outer side and a rail head shoulder surface joining the top side and the outer side, the rail head shoulder surface including a cross-sectional curvature having a shoulder radius;

each one of the first and second wheels has a single diameter cylindrical surface engaging the top side of the rail head and first and second axially spaced apart radially extending circumferential flange means respectively facing and spaced a distance from the outer side and the inner side of the rail head when the crane is in said position parallel to the rails, the spacing distance of the first flange means of each first and second wheel from the outer side of the rail head which the first flange means of said wheels each face, being such that, when the crane is in one of the skewed positions and the leading skewed wheel is toed toward the rail head in the direction of travel of the crane, the first flange means of the leading one of the first and second wheels engages the faced outer side of the rail head and the engagement of the second flange means of the lagging one of the first and second wheels with the faced inner side of the rail head is minimized; and

the first flange means of each one of the first and second wheels further including a circumferential flange juncture surface adjoining the cylindrical surface, each flange juncture surface facing a respective one of the rail head shoulder surfaces and having a cross-sectional radius such that the flange juncture surface of the leading skewed wheel and the respective faced rail head should surface having a cross-sectional line of engagement in each one of the skewed positions of the crane whereby friction is maximized between the faced rail head outer side and the first flange means of the leading skewed wheel to decrease its linear speed and cause the crane to move to said parallel position.

2. The traveling crane according to claim 1 wherein:

each flange juncture surface has an initial different cross-sectional radius than the cross-sectional radius of the rail head shoulder faced by the flange juncture surface; and

each flange juncture surface has a cross-sectional radius substantially equal to that of the faced rail head shoulder surface as a result of wearing engagement of each flange juncture surface with the faced rail head shoulder surface during skew of the crane.

3. The traveling crane according to claim 1 wherein each flange juncture surface has a cross-sectional radius substantially equal to the cross-sectional radius of the faced rail head shoulder surface.

4. In a traveling crane supported on a pair of spaced apart generally parallel rails and including a frame spanning the space between the rails, a truck attached to the frame adjacent each rail, at least one wheel rotatably mounted on each truck in engagement with one of the rails for movement at a linear speed in the direction of the parallel rails whereby the crane travels along and in a position parallel to the rails, the crane also having two oppositely skewed positions while traveling on the rails such that one of the first and second wheels is a leading wheel and the other wheel is a lagging wheel in each of the skewed positions in the direction of travel of the crane, and drive means for rotating a first wheel on one of the trucks and asecond wheel on the other of the trucks independently of each other, the combination comprising:

a rail head on each rail, each rail head having a top side, an inner side, an outer side and a rail head shoulder surface joining the top side and the outer side, the rail head shoulder surface including a cross-sectional curvature having a shoulder radius;

each one of the first and second wheels has a single diameter cylindrical surface engaging the top side of the rail head and first and second axially spaced apart radially extending circumferential flange means respectively facing and spaced a distance from the outer side and the inner side of the rail head when the crane is in said position parallel to the rails, the spacing distance of the first flange means of each first and second wheel from the outer side of the rail head which the first flange means of said wheels each face, being such that, when the crane is in one of the skewed positions, and the leading skewed wheel is toed toward the rail head in the direction of travel of the crane, the first flange means of the leading one of the first and second wheels engages the faced outer side of the rail head and the engagement of the second flange means of the lagging one of the first and second wheels with the faced inner side of the rail head minimized;

the first flange means of each one of the first and second wheels further having a circumferential flange juncture surface adjoining the cylindrical surface, each flange juncture surface facing a respective one of the rail head shoulder surface surfaces and having a cross-sectional radius substantially equal to that of the respective faced rail head shoulder surface; and

in each one of the skewed positions of the crane, the flange juncture surface of the leading skewed wheel of the first and second wheels engages the faced rail head shoulder surface, such engagement being maximized due to the substantially equal cross-sectional radii of the facing flange juncture surface and rail head shoulder surface, whereby said maximum engagement increases the friction between the facing rail head outer side and the first flange means of the leading skewed wheel to decrease its linear speed and cause the crane to move to said parallel position.

5. The traveling crane according to claim 4 wherein the cross-sectional radius of the flange juncture surface of the first wheel differs from the cross-sectional radius of the rail head juncture surface which the flange juncture surface faces by not more than 1/16 inch.

6. The traveling crane according to claim 4 wherein:

each flange juncture surface has an initial cross-sectional radius larger than the cross-sectional radius of the rail head shoulder faced by the flange juncture surface; and

each flange juncture surface has said cross-sectional radius substantially equal to that of the faced rail head shoulder surface as a result of engagement of each flange juncture surface with the faced rail head shoulder surface during skew of the crane.

7. In a traveling crane supported on a pair of spaced apart generally parallel rails and including a frame spanning the space between the rails, a truck attached to the frame adjacent each rail, at least one wheel rotatably mounted on each truck-in engagement with one of the rails for movement at a linear speed in the direction of the parallel rails whereby the crane travels along and in a position parallel to the rials, the crane also having two oppositely skewed positions while traveling on the rials such that a first wheel on one of the trucks and a second wheel on the other of the trucks respectively have a relative leading and lagging position when the crane is in one of the skewed positions and an opposite leading and lagging position when the crane is in the other of the skewed positions, and drive means for independently rotating the first and second wheels, the combination comprising:

at least one of the rails including a head having a top side, an inner side, and outer side and a rail head shoulder surface joining the top side and the outer side, the rail head shoulder surface including a cross-sectional curvature having a shoulder radius;

each one of the first and second wheels has an axially extending single diameter cylindrical surface engaging the top side of the rail head, first and second axially spaced apart flanges respectively facing and spaced a distance from the outer side and the inner side of the rail head when the crane is in said position parallel to the rails, a circumferential flange juncture surface joining the cylindrical surface and the first flange of each first and second wheel, the flange juncture surface facing the rail head shoulder surface and having a cross-sectional flange radius of curvature substantially equal to that of the faced rail head shoulder surface;

the first and second circumferential flanges on each first and second wheel respectively facing and spaced a distance from the outer side and the inner side of the rail head, the distance of the space of the first flange of each first and second wheel from the outer side of the rail head which the first flange of said wheels each face, being less than the distance of the space of the second flange of each first and second wheel from the inner side of the rail head which the second flange of said wheels each face; and

the first flange of the leading wheel of the first and second wheels, when the crane is in one of said skewed positions, is toed toward the outer side of the rail head which the first flange faces in the direction of travel of the crane and the facing flange juncture and rail head shoulder surfaces are in engagement with each other due to their substantially equal cross-sectional radii and due to said lesser spacing distance of the first flanges of the first and second wheels whereby a high level of friction develops between the engaged juncture and shoulder surfaces to decrease the linear speed of the leading wheel and correct the skew of the crane.

8. The traveling crane according to claim 7 wherein the cross-sectional radius of at least one of the flange juncture surfaces differs from the cross-sectional radius of the rail head juncture surface which said one flange juncture surface faces by not more than 1/16 inch.

9. The traveling crane according to claim 7 wherein:

at least one of the flange juncture surfaces has an initial cross-sectional radius larger than the cross-sectional radius of the rail head shoulder faced by said one flange juncture surfaces; and

said one flange juncture surface has said cross-sectional radius substantially equal to that of the faced rail head shoulder surface as a result of wear engagement of said one flange juncture surface with the faced rail head shoulder surface during skew of the crane.

10. A method for correcting skew of a traveling crane supported on a pair of spaced apart generally parallel rails and including first and second substantially axially aligned wheels each engaging a different one of the rails for movement at a linear speed in the direction of the parallel rails whereby the crane travels along and in a position parallel to the rails, the crane also having two oppositely skewed positions while traveling on the rails such that the first and second wheels respectively have a relative leading and lagging position when the crane is in one of the skewed positions and an opposite leading and lagging position when the crane is in the other of the skewed positions, and drive means for independently rotating the first and second wheels, comprising the steps of:

providing an outwardly facing curved shoulder surface on an outer side of the rail head of each of the pair of rails;

providing each of the first and second wheels with a cylindrical running surface and a flange having a flange surface facing an outer side of a rail head;

providing a flange juncture surface between the cylindrical surface and the flange surface with a curvature substantially equal to that of the curved rail head shoulder surface; and

engaging the flange juncture surface of the leading wheel, when the first and second wheels are in one of the skewed positions, with the rail head shoulder surface along the equal curvature surfaces to produce friction force, decreasing the linear speed of the leading wheel and correcting the skew.

11. The method according to claim 10 wherein each shoulder surface has a radius of curvature, comprising the further steps of:

forming each flange juncture surface with a radius of curvature larger than that of curved shoulder surface faced by the flange juncture surface; and

rotating the flange juncture surface in engagement with the faced shoulder surface to wear the flange juncture surface to a radius of curvature equal to that of the shoulder surface.