托辊的作用是支撑输送带和物料重量。托辊运转必须灵活可靠。减少输送带同托辊的摩擦力，对占输送机总成本25%以上的输送带的寿命起着关键作用。虽然托辊在带式输送机中是一个较小部件，结构并不复杂，但制造出高质量的托辊并非易事。
The role of the idler is to support the conveyor belt and material weight. The operation of idler must be flexible and reliable. Reducing the friction between conveyor belt and idler plays a key role in the service life of conveyor belt which accounts for more than 25% of the total cost of conveyor. Although the idler is a small part of belt conveyor and its structure is not complicated, it is not easy to produce high quality idlers.
判断托辊好坏的标准有以下几条：托辊径向跳动量；托辊灵活度；轴向窜动量。
The criteria for judging the quality of idlers are as follows: radial runout of idlers; flexibility of idlers; and axial runout.