By "repair men", do you mean Gus?
Gus (forklift.mdl)
If so the model name is forklift.mdl and it's one of Half-Life standard assets (so this version from
Half-Life/valve/models
can be used in your mod).
On the other hand, if you mean some player model then there's
/models/player/HL_Construction/HL_Construction.mdl
and
/models/player/HL_Gus/HL_Gus.mdl
from Sven Co-op and these are specific to SC, which means that you should ask for permission to use these in your mod, and possibly need to do some conversion as the player skeleton and/or sequences are different between HL and SC.
As for using assets from the main games (such as Half-Life, Blue Shift and Opposing Force), it's generally fine to do so for a HL/BS/Op4 mod. So re-using a main game texture in your mod's WAD is all good.
It's only a problem if you lift these assets out of these games and put them in another non-Valve game.