Lots of progress on the design.

Attachment 6271
We have struggled with the locking mechanism for the electric arm.
The resultant forces from the hydraulic cylinder arm are at a ratio of about 3:1, so 24 tonnes of force to resist!
With a shot bolt or ratchet set up, the material would just deform, or needed to be very bulky. the failure mode is also pretty catastrophic.

We have decided to go with a band brake driven by a 32bore hydraulic cylinder.
http://www.tribology-abc.com/calculators/e3_5d.htm
It is a lighter set up, it has a much kinder failure, in that the drum will just slip, and it should still give us enough holding force to give us our 8 tonnes at the tip.

All of these mechanisms have took their toll on our weight budget. Everything in the photo is 97kg currently, and we still have to add hydraulic oil, hoses and Armour ( which will probably be mostly 15mm PE)

The remaining design work will mainly be taking weight out of the existing components to free up weight for armour. We hope the design will be finished within a week!


Most of the components are laser or water cut, so we are hoping the rest will go together pretty smoothly...