Assuming you know what you're talking about in terms of Schlitten and Werkzeugeinheit, I'd say something like "Carriage and tool unit (strange term) can be locked near the mast guide."

I'd avoid "can be effected," for one.

Hint to michma: dude's removal of your nominalization ("A locking of") that was carried over from the German is a good pattern to follow. Such overuse of nominalizations is considered weak writing in English.

This has all the hallmarks of a patent text, in which case the nominalization ("a locking") and the use of the verb "to effect" are perfectly acceptable/normal, not only in translations from German but also in patent specifications written in English in the first place.

I would, however, quarrel with "close proximity". "in proximity to" is sufficient for "nahe"; "close" is redundant.