求翻译：用滑轮和皮带传动也非常普及。它们也能改变机床的速度。齿轮和滑轮都在转轴上转动，而转轴必须安防在轴承中。有时两轴之间可能还有连轴节。可以用离合器来使转轴开始转动或停止转动。是什么意思？

With a pulley and belt drive is also very popular. They also can change the speed of the machine. Gears and pulleys on the shaft rotation, the shaft must be security in the bearing. Sometimes there may be two-axle shaft section. Can use the clutch to the shaft starts to rotate or stop rotating.

The pulleys and belt drive is also very popular. They are also able to change the machine's speed. Pinion gears and pulleys are all on the spindle turning, the hinge must be security in the bearing. Sometimes there may be between two-axis shaft section. You can use the clutch to start turning the sp