Detail of two-axle trailer Karosa B40's coupler. In the territory of Czechia, trailer cars for a-buses were being used approx. from 40s of 20th century (demand to transport more people) to 70s of 20th century (massive using of articulated buses). Trailer cars were used with both a-buses and t-buses in Czechoslovakia. Usually Karosa B40 is coupled with trolleybus Škoda 8Tr but B40 can be also coupled with a-bus Škoda 706 RTO or with any "old" t/a-bus which can be coupled with trailer (Czechoslovakian buses are more or less compatible with Czechoslovakian trailers and Jelcz trailers). Nowadays in the Czech Republic is forbidden using trailer cars which transport people in road transport (and for t-buses) except for historical vehicles on special rides.