Development of Resistance Roller LT

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Sean Murrells – Tool & Design Manager

1. Summary

Lynar Manufacturing runs a high volume electrical circuit connector for Truck-Lite Europe Ltd which needs new tooling as the old tooling is worn beyond repair.

2. Introduction

Truck-Lite Europe Ltd is a global leader in the design and manufacturing of vision systems servicing the Automotive and Commercial Vehicle Industry. Under the brand names of Truck-Lite, Rubbolite, FER and Signal-Stat they have become a fore runner in LED and incandescent lighting technology, mirror manufacturing and trailer assemblies. Servicing the truck, trailer, off-road and military sectors as well as the independent aftermarket they have an extensive portfolio of OEM customers and over 90 years of experience in an ever changing and evolving marketplace.

Example of product


3. Product Detail

Mr O’Connor and Lynar Manufacturing identified that the new design, The Resistance Roller LT, would need to be:

  • Lightweight (10.8 kg maximum).
  • Able to fit into a racing wheelchair crate.
  • Have removable rollers.
  • Be stable on most ground conditions.

4. Initial Design Methodology

The initial prototype had been presented to British Athletics, and their recommendations, as well as design alterations put forward by Lynar Manufacturing and Mr O’Connor, initiated the following changes:

  1. Smaller roller size.
  2. Frame made smaller and lower due to the above roller reduction, to help to save weight.
  3. Main cross bar redesigned to provide a more compact unit.
  4. Wheelchair cradle mounts made to flip down for shipping purposes.
  5. Resistance device added with adjuster to vary during training. This change was not requested by British Athletics, but we thought it would improve the product’s all-round potential.

5. Findings

The design changes agreed gave the new frame the following unique selling points:
• The wheelchair mount was able to have its main rollers totally removed and packed into the same crate as the racing
wheelchair itself, making the whole product completely portable. This design also ensured that the A-frame would protect
the chair in transit, enabling one trainer unit to accompany one athlete. Current designs mean that there can be one trainer
for five to ten athletes when attending foreign competitions, championships or Paralympics.
• The mount was now able be adjusted to fit most racing wheel chairs on the market, including smaller youth models.

6. Chair Design

Several modifications were modelled and considered for weight-saving purposes.
Also, the final paint finish was decided before manufacture. The patriotic colours of red, white and blue were chosen specifically for
British Paralympic Richard Chiassaro.
The design was drawn in 3D Computer-Aided Design (CAD) using the latest Solidworks software which, upon addition of material
detail, automatically gives designers the actual weight of full assembly.

3D Model


7. Manufacture

The main frame was manufactured from high quality aluminium tube, to ensure robustness while maintaining a lightweight and
aesthetically pleasing finish to the product. High quality stainless steel fittings, studding, bolts and knurled adjusters were assembled
onto the frame.
Heavy duty steel bearings were used, and specially designed to resist dirt and other foreign matter. These bearings will help to
ensure longevity of the frame during regular use. Non-slip pads were also fitted to each foot to stop the frame slipping, adding
further to the all-round stability of the frame.

Assembly during manufacture

Bare Frame

Testing – With Richard Chiassaro


8. Final Adjustments

After otherwise successful testing, it was discovered that the resistance unit did not exert enough force at its highest setting.
The frame was then again taken apart with the individual pieces masked and sent for powder coating in the agreed colours. In
the meantime, the MAG unit, which creates the force, was also modified to increase resistance at the upper end, thus further
emulating steep gradients.

The Finished Unit


9. Conclusion

One final test revealed that the frame was now fully functional according to Mr Chiassaro’s requirements, including the resistance
adjustment. The frame was then finalised to be tested for one full month, before being presented to British Athletics for their approval.

10. Testimonial

“I was extremely pleased with the initial enthusiasm I received from Lynar which continued throughout
the build, it is one thing knowing what you require, but it is another finding someone on the same plain
as yourself who can interpret your thoughts. The unit had been on bits of paper and in my mind for two
years. Thanks to Sean and Lynar Manufacturing, it is now an item being tested.
Thanks Lynar.”
Tony O`Connor

11. Acknowledgements

Many thanks to:
Tony O’Connor and World Class GB Paralympian Richard Chiassaro
Lynar Manufacturing Ltd

12. Copyright and Patent Pending

Tony O`Connor