由于木制車留存在許多問題,如木材消耗多、寿命短(易腐朽)、边框大(影响采光面积)和易吸水膨胀(影响升降灵活)等,所以在进厂修理的客車中,許多路局、段要求改为鉄窗。为便于修換,在改造的設計中,窗的組成一般均同于yz21型铁窗的各 There are many problems with wooden vehicles, such as heavy wood consumption, short life span (easy decay), large border (affecting lighting area) and easy water swelling (which affects the flexibility of lifting). Therefore, in the repair of passenger cars, many roads Bureau, paragraph requirements changed to window. In order to facilitate the replacement, in the transformation of the design, the composition of the window are generally the same with the yz21-type bar