Had a couple of groups across the underground tyrolean today with the load cell which made for some (relatively) interesting observations.

We set the tyrolean up with a STOP as a clutch device and the usual 5:1 haul. 2 of us achieving a peak of around 2.5kN with the ropes tension dropping down to around 1.6kN by the time the first group started to head across. The first (of 3) groups to use the traverse were around 10 x Yr 11 students. Peak loads went up to around 3kN at times, with the tension in the rope dropping right down to 1kN by the time all 10 had gone across.

The second group to head across were a lot smaller, group of 10 x Yr 5 pupils plus a couple of adults. Before sending them across 2 of us re-tentioned the tyrolean, again peaking around 2.5kN, but this time the tension stabilising around 1.8kN. The time the tension in the rope after each student crossed didn’t seem to drop so much, which may be due to the smaller size of the students, or that the knots etc had snitched up.

The last person to head across was a member of staff, probably around 100-125kg. Given all the students were quite short, the travelling rope attached to the tandem pulley on the traverse had been adjusted so students could easily clip to it. The rope as adjusted for the taller adult, however there was still a little slack in the adults cows tails as they set off. The result was a somewhat dynamic launch from the start of the tyrolean, some wet feet and a peak load of 4.5kN

In contrast another adult (admittedly smaller) was clipped to the traverse with very tight cows tails resulting in a far lower peak load (2.57kN).

After the dynamic loading the overall tension in the tyrolean dropped significantly (in comparison to previous students), probably due to the STOP slipping a little in use.

Goes to show that although good fun, dynamic loading does generate some pretty high forces, and drops the overall tension in the system!

You can see all the data (well the last 30mins worth as it turns out the load cell only records 30mins of data so we lost all the results from the first group to use the traverse) by clicking on the link below. The sheet with todays results is labelled “MS Mine March 16”

Click here for all data (spreadsheet)


Leave a Reply