行驶系 meaning in English

going system
running gear

Road vehicles - interchange of digital information on electrical connections between towing and towed vehicles - part 2 : application layer for brakes and running gear
道路车辆.牵引和被牵引车辆之间电气连接的数字信息的交换.第2部分:制动器和行驶系的应用层
Road vehicles - interchange of digital information on electrical connections between towing and towed vehicles - part 3 : application layer for equipment other than brakes and running gear
道路车辆.牵引和被牵引车辆之间电气连接的数字信息的交换.第3部分:除制动器和行驶系以外的设备用应用层