This trailer from the 60`s is based on the dutch Nooteboom, type ODU (Trailer, Low bed, Swivelable) and the Langendorf (Germany). At first it is built with turntable axle under neck, later on as trailer behind 2/3-axle semi trucks.
The back axle consist of two swivel pendle axles, each for 10 ton. With this the back of the trailer has an easy acces to load/unload rolling equipment (crane/ dozer, etc). So load of 20 ton were normal to do.