Positive tracking

11:11 Oct 24, 2017 

Mise en traction

09:44 Oct 24, 2017 

Without a great deal of conviction, and even less knowledge, I would hazard a guess that 'positive' here is being used in the same sense as it is in 'positive restraint' (and other similar uses in mechanical engineering) — i.e. something is physically blocked in some way, as distinct from mere 'frictional restraint', where something is simply prevented from (e.g.) sliding by sufficient pressure creating friction (e.g. certain types of clamping); so here, maybe you have these welded things providing some kind of definite (= positive!) guidance, rather than relying on say just the dynamic running characteristics to keep it in place; like the difference, say, between a belt running in a V-pulley compared to a flat belt running on a smooth pulley.