无级的英文：
stepless

Hydrostatic wheel and travel drive with four-range infinitely variable speeds, anti-slip drive
静液压全轮驱动，四档无级变速，防滑驱动。

With stepless speed regulator, you may control this vehicle with ease.
本车装有无级变速操纵杆，包您操纵自如。

"Stepless transmissions use belts, chains, or rolling-contact bodies. "
连续传动器使用传动带、链条或者滚动接触体。