Capital allowances on an overhead crane

I understand that capital allowances are available on an overhead gantry crane, but to what pool should the expenditure be allocated?

I cannot find any evidence to suggest that it would have to be allocated to the Special Rate Pool unless it is deemed to fall under the integral features umbrella of a lift, an escalator or a moving walkway. I think there is an argument to state that it is an item of trade specific plant & equipment and is not seen to be in the same catagory of a lift or escalator, so should be allocated to the Main Pool.

Can anybody shed some light on the matter?