What is PLH?
Trailer grouping according to their technology and materials:
- Trailers with a welded frame
- Bolt-joint trailers (PLH)
Bolt-joint trailers (PLH). Trailer for which welded structures are avoided when constructing and designing bearing joints and the superstructure. Bolts and rivets are used to connect the details and joints. The construction is based on metal sheet processing technology.
Nowadays the manufacturing of bolt-joint trailers involves 3D CAD modelling and the use of computer-based high-tech metal sheet processing devices. The history of this manufacturing mode shows that this is the most successful technological approach in trailer manufacturing in terms of the price-quality ratio. The use of bolt-joints ensures a better appearance of the trailer and an excellent resistance to fatigue failures (e.g. airplanes, too, do not have any welded seams), although product development requires higher qualification and larger investments.
Readymade bought-in galvanized metal sheets are used to manufacture the bolt-joint trailers. Bolt-joint trailers have started to dominate especially in the category of O1 common trailer market.
Trailers with a welded frame. Trailer with a welded frame and a drawbar. Constructions are usually hot-dip galvanized. The automation of the manufacturing process of trailers with a welded frame is not very common. Boat trailers and braked trailers of category O2 often have welded frames.