自行式工程机械采用液压马达或行星轮传动来驱动车轮日趋增多。液压马达可直接安装在轮载上，减少了诸如传动轴等部件，从而扩大了净空间。以往限制液压马达的使用主要是价格问题，因为两个、三个或四个马达与单马达通过传动轴和齿轮箱驱动系统相比造价明显偏高。1驱动部件最近 Self-propelled construction machinery using hydraulic motor or planetary wheel drive to drive the growing number of wheels. The hydraulic motor can be mounted directly on the wheel, reducing parts such as the drive shaft, thus expanding the net space. In the past, the use of a hydraulic motor was limited primarily to price, as two, three or four motors were significantly more expensive than single-motor drives through drive shafts and gearbox drives. 1 drive unit recently