【简答题】
如图所示的齿轮系中,已知各齿轮的齿数为Z<sub>1</sub>=32,Z<sub>2</sub>=16,Z<sub>3</sub>=64,求下列两种情况时,齿轮3的转速n<sub>3</sub>及其转向。<br/><img src="https://nimg.ppkao.com/2018-06/liuqianlan/2018061315291577190.jpg?sign=a3328be6773b690e45e38c1b289753ad&t=62d1aa5e"/><img src="https://nimg.ppkao.com/2018-06/liuqianlan/2018061315294219179.jpg?sign=94d878290217aeaf152e49c2aae5851a&t=62d1aa5e" style="width: 264.006px; height: 23.006px;"/><br/><img src="https://nimg.ppkao.com/2018-06/liuqianlan/2018061315300785525.jpg?sign=d37830b7b1f9bf523260d66f8dee292d&t=62d1aa5e"/>