GB2433120A

GB2433120A - Railway wheel diameter measuring tool

Info

Publication number: GB2433120A
Application number: GB0524951A
Authority: GB
Inventors: Ian Wicks
Original assignee: MARCROFT ENGINEERING Ltd
Current assignee: MARCROFT ENGINEERING Ltd
Priority date: 2005-12-07
Filing date: 2005-12-07
Publication date: 2007-06-13
Also published as: GB0524951D0

Abstract

The tool, which determines diameter from chord height, consists of a mounting beam 1 machined from a solid bar of aluminium or similar material. Set into the centre of this beam is a horizontal digital slide instrument 10. The slide end of this instrument is modified to a radius chisel tip 12. Mounted at each end of the beam are two hardened steel centre points 8. Bolted to the back of the beam are two spacer bars which carry a back plate and button magnets which locate the centre points and slide at the required axial position on the wheel periphery to measure its diameter. If damaged, the digital instrument 10 can be easily removed and replaced by a semi-skilled operator on site. The positions of the centre points 8 can be varied.

Description

Page 1 Railway Wheel Diameter Tool

Description

Railway wagon wheels need to have their diameters measured on a regular basis to detect wear and whether the wheel needs either re-machining or replacing. A cost effective way to measure wheels in situ has been a major problem in the industry since regular maintenance procedures were introduced. Maintenance work is often carried out in a harsh environment where sophisticated equipment has a limited shelf life and is prone to abuse.

This tool is for the purpose of measuring the diameter of a railway wagon wheel in situ; where the access to the wheel is severely limited by: the brake gear, the bogie frame, the suspension system etc. i.e. it is not possible simply to measure the diameter directly across the rim.

There is also an additional problem in measuring the wheel diameter, in that a railway wagon wheel is tapered and the diameter must be measured at a defined point on the taper to meet railway standards.

The diameter tool comprises of the following parts: 1. One mounting beam machined out of solid aluminium bar or similar material.

2. Two spacer bars.

3. Four countersunk headed spacer screws.

4. Two digital instrument fixing screws.

5. One back plate.

6. Four button magnet fixing screws.

7. Four button magnets.

8. Two centre points manufactured from hardened steel.

9. Two centre point clamping screws.

10. One horizontal digital slide modified to suit new application.

11. One slide stop cap screw.

12. One modified slide rule.

13. Calibration bar.

14. Conversion Chart.

The following drawings are used to assist in the description of the tool: Figure 1 Diameter Tool Assembly (Front View) Figure 2 Diameter Tool Assembly (Side View) Figure 3 Chisel tip slide (Side View) Figure 4 Chisel tip slide (Front View) Figure 5 Conversion Chart. Pag2

Principles of how the tool works: The diameter tool works on the principle that: it takes three points to define a circle's diameter.

The first two points are fixed at manufacture at a known distance and are physically defined by the two centre points item 8. These create the standard chord length on which the calculations on the conversion chart are based.

The third point is variable and is created by the digital slides chisel tip item 12: this bisects the two fixed points at ninety degrees and is equidistant between them.

By knowing the chord length and the chord height as measures by the digital slide a chart See Figure 5 can be created to tell the operator the wheel diameters for a range of chord height measurements.

Due to the geometry of the wheel an extra set of centre mounts have been provided to keep the tool profile as low as possible for a wide range of wheel diameters without affecting its specified accuracy.

Brief description of how to use the diameter tool:

1. Select the centre point centres for the wheel range to be measured and fit centre in the corresponding holes.

2. Rest the two centre points at each end of the calibration bar.

3. Switch on the digital instrument.

4. Slide the digital slide down to the calibration bar until the chisel tip is touching the bar.

5. Zero the digital instrument at this point. (Note: Once the instrument is zeroed it will retain this datum even if the instrument is then switched off) 6. Take the diameter tool to the wheel and fasten the back plate to the back flange of the wheel via the button magnets. This will position the centre point at the correct distance on the tapered flange. See Figure 2 7. Slide the tool towards the wheel until the two centre points are in contact with the flange face.

8. Switch on the digital instrument and slide the digital slide toward the flange until the chisel tip touches the flange face. Now all three points of the tool should be in contact with the wheel. See Figure 1 9. Record the reading on the digital instrument.

10. Using the conversion chart find the nearest chord height to the recorded reading, in the next column you will find the wheel diameter.

11. if the operator feels the wheel surface could be damaged he can take additional readings and take an average.

Claims

Page 3 Claim 1. A diameter tool that uses a horizontal slide instead of

a vertical slide thus enabling the tool to be calibrated each time it is used, therefore rendering it unaffected by wear and misuse.

2. A diameter tool as in Claim I where the centre points can be assembled incorrectly without noticeably affecting the accuracy of the tool: due to the fact the tool is calibrated before use, i.e. even if the centre points are not setting fully on their shoulders the tool will still measure true.

3. A diameter tool that has a radius chisel tip to allow for misalignment of the horizontal slide with reference to the centres without affecting the reading.

See Figure 4 4. A diameter tool as in Claim 2 which allows the tool to be calibrated at an angle of or -20 degrees from the vertical due to the chisel tipped slide.

See Figure 3 5. A diameter tool that has twin sets of centres so as to reduce the profile height enabling it to be used in a very confined space. See Figure I 6. A diameter tool with a cheap replaceable digital instrument that can be removed and replaced if damaged by a semi-skilled operator.

7. A diameter tool with a digital instrument from which an output can be taken to a processor that will read the diameter without the need of a conversion chart.

8. A diameter tool that positions the centre points at the correct point on the taper by means of spacer bars and button magnets. See Figure 2 9. A diameter tool that only has two centre point positions, where the profile height or accuracy are not so critical.