Around 2006–2007 I started to get the feeling that the rollers I was using were somehow defected as the grab wasn’t reversing timber properly. A thought was simmering on my mind: using sprocket chains to build some kind of pack that would serve as a feeding roller in my harvester’s grab. 

 

I let the idea incubate in the background, but decided to have laser cut symmetrical spikes done to replace the conventional involute spikes. The grip on the roller was significantly better than with the short spiked iron rollers I had had before, and reversing had improved as well. I narrowed down the tips of the spikes, which helped the rollers stay somewhat cleaner. 

 

I told a good associate of mine about the matter of spiked discs and them likely getting clogged up. He responded right away that there should be some kind of cleaner in the rollers. He sure knew what he was talking about. The first spikes were very sharp and sank really deep into the timber. However, the grip was tremendous, which encouraged me to further develop the roller. By both improving on blocking the sinkage and increasing the number of spikes the excessive sinkage of the rollers into the timber has been gotten under control while maintaining sufficient grip. 

 

I have subsequently performed testing on several different possible structural solutions. The latest of them crossed my mind in one late February afternoon: the collapsible structure of bolted joint, which had been occupying my mind several times before. The sleeves/casing in-between make the structure robust and ensure that both dismantling and re-assembling the roller during maintenance is easy. 

 

I have been fortunate to get open-minded and excellent cooperation partners and test users as well as laser cutting and machining businesses that have helped with manufacturing the various parts of the roller. 

 

Without the honest positive and negative feedback from the users there’s no way I would have been able to develop the rollers to their present working condition.

 

Thank You for all the input that helped me develop the rollers. I hope dearly the collaboration will continue in the future as well. 

 

 

In Lappeenranta August 10th, 2012, Timo Penttimies, logger and roller machinery developer 

1. Manufacturing by laser cutting of Hardox 600 material, plate thickness 10 mm.

2. Hardox 600 by SSAB (A Swedish leading steel) is an extremely hard steel wear plate. Yield strength 1650-2000 N/mm2 (ordinary structural steel 335-520 N/mm2, 8.8 bolt 880 N/mm2).

3. Supporting cases by automatic machinery. Steel or extra hard aluminium.

4. Supporting cases bear the structural forces while the bolts keep the roller in form.

5. Reliable, overdimensioned multi-bolt assembly: 8-10 bolts, M14/ strength 12.9.

6. Excellent grip due to numerous sharp spikes.

7. Steep spike angle: Roller sticks to timber with lower pressure.

8. Great reversing properties on the grab, the symmetrical structure of the spike.

9. The sinkage limiter prevents the spikes from sinking too deep into the wood.

10. A damaged roller part is easy to move to farther back or change to a new one if necessary.

11. The roller’s cleaner keeps the roller clean at all times, grip is maintained.

12. Mass processing qualities found great as well.

13. In conclusion the finished product is a roller with good operating characteristics. 

14. Utility patent pending.

15. After-sales service will be arranged.

16. To guarantee the quality:

17. The two (2) year or 4000 hour warranty covers failures and defects in structure and materials. 

Some steel related links: 

Roller parts are laser-cut by PLP.fi

 

About Hardox