When I was at Halton 1993 and 1994 they used a retrieve winch at times
with a multi-drum winch (two drum). I don't recall exactly how they were
working the two drums, but I do recall (from having driven it a few
times) that operating the retrieve winch took some care in regard to
timing when to engage it for the retrieve (which I seem to recall was
done just after the glider released and before the cable reached the
ground - therefore it used a parachute). It was quite easy to break the
retrieve cable as I recall.

Maybe someone who was there at Halton and more expert in its
construction and use could pass on some details?

Rgds,

Derrick Steed