直至1933年,在铁路车辆厂焊接仅仅用于修理损坏的铆接件或下部设备。同年美国芝加哥的普尔曼车辆厂用焊接方法制造了带4个料斗的漏斗车的上部结构(车体上部)。这种车的底架,包括料斗是单个铸件。1935年,美国密尔沃垫铁路开始用焊接方法制造了35辆带水平加强筋的棚车的车体及车体下部结构。差不多在同一时间,密尔沃基铁路也开始制造焊接结构的客车。以后,于1937年,美国铁路协会(AAR)研制了一种标准棚车设计。该设计采用了由两根结构钢Z形 Until 1933, welding at the rail vehicle factory was only used to repair damaged rivets or lower equipment. In the same year, the Pullman Vehicle Works, Chicago, USA, manufactured the upper structure of the hopper car with four hoppers (the upper part of the car body) by welding. The car’s chassis, including the hopper, is a single casting. In 1935, the Milwaukee Mound in the United States started the welding of the bodywork and the lower body structure of 35 boxes with horizontal stiffeners. Almost at the same time, the Milwaukee Railway began to make welded buses. Later, in 1937, the American Railroad Association (AAR) developed a standard box car design. The design uses two structural steel Z-shaped