# US 5,706,736 A · Polar crane and related method

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 5,706,736 A
- Document ID: US5706736A
- Status: Granted
- Kind: A
- Application number: 08/584,223
- Filed: 1996-01-11
- Granted: 1998-01-13
- Earliest claimed: 1996-01-11
- Assignees: Harnischfeger Corporation
- Inventors: George E. Thorsen
- Web page: https://patentgrep.com/patent/US5706736A

## CPC

- B66C 17/00: Overhead travelling cranes comprising one or more substantially horizontal girders the ends of which are directly supported by wheels or rollers running on tracks carried by spaced supports
- B66C 9/16: with means for maintaining alignment between wheels and track
- B66C: CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES ({specially adapted for lifting invalids A61G7/10;} rope, cable, or chain winding mechanisms, braking or detent devices therefor B66D; specially adapted for nuclear reactors G21)

## Abstract

Disclosed is a polar crane supported by a rail and having a bridge and a bridge-supporting end truck at each end of the bridge. Each end truck has, for either direction of revolving bridge motion, a leading wheel contacting the rail. In the improvement, the leading wheel of each end truck has a single flange and the flange is inward of the rail. Skewed crane "lock-up" is thereby substantially prevented. A related method for modifying a polar crane includes raising the first end truck away from the rail, removing a two-flange wheel (the leading wheel) from the first end truck and installing a one-flange wheel in place thereof.

## Claims

### Claim 1

In a polar crane supported by a rail and having a bridge and a pair of spaced-apart linear bridge girders and a bridge-supporting end truck at each end of the bridge girders, and wherein each end truck is circumferentially-spaced from the other end truck, each end truck includes first, second and third wheels supporting the weight of the girders on the rail, the improvement wherein:
the first wheel on each end truck is a leading wheel for a particular direction of revolving bridge motion on the rail;
each of the leading wheels has a single flange which is inward of the rail; and
as to each end truck, the second wheel is between the first and third wheels and has two flanges.

### Claim 2 (depends on 1)

The crane of claim 1 wherein:
the rail forms a circle;
the bridge has a longitudinal centerline; and
the centerline is along a chord of the circle.

### Claim 3 (depends on 1)

The crane of claim 1 wherein:
the bridge has a longitudinal centerline; and
each of the second leading wheels is spaced from the centerline.

### Claim 4

In a hybrid polar crane supported by a pair of linear, spaced-apart rails and having a bridge and a bridge-supporting end truck at each end of the bridge, the improvement wherein:
the bridge supports a rotating trolley on a circular rail;
the trolley includes two trolley end trucks, each trolley end truck is circumferentially-spaced from the other end truck, each trolley end truck is supported on the circular rail and has, for a particular direction of rotation of the trolley on the circular rail, a leading wheel and a second wheel contacting the circular rail;
the leading wheel of each trolley end truck has a single flange and the flange is inward of the circular rail; and
the second wheel has two flanges.

### Claim 5

A method for making a polar crane for handling loads eccentrically-imposed thereon and including the steps of:
providing a pair of end truck frames for attachment to a pair of linear girders, each frame having an inward side, an outward side and first, second and third wheel mounting positions;
mounting a first wheel at the first wheel mounting position, such first wheel having a flange only toward the inward side; and
mounting a second wheel at the second wheel mounting position, such second wheel having two flanges.

### Claim 6 (depends on 5)

The method of claim 5 including mounting a third wheel at the third wheel mounting position, such third wheel having at least one flange and the said at least one flange is toward the inward side.

### Claim 7 (depends on 6)

The method of claim 6 wherein the frame has a fourth wheel mounting position and the method includes:
mounting a fourth wheel at the fourth mounting position, such fourth wheel having a flange only toward the inward side.

### Claim 8

A method for making a polar crane for handling loads eccentrically-imposed thereon and including the steps of:
providing an end truck frame having an inward side, an outward side and first, second, third, fourth, fifth and sixth wheel mounting positions;
mounting first and second wheels at the first and second mounting positions, respectively, such first and second wheels each having a flange only toward the inward side;
mounting third and fourth wheels at the third and fourth mounting positions, respectively, each of the third and fourth wheels having two flanges; and
mounting fifth and sixth wheels at the fifth and sixth wheel mounting positions, such fifth and sixth wheels each having a flange only toward the inward side.