托辊是带式输送机的重要部件，种类多，数量大。作用是支承皮带，减少皮带运行阻力，并使皮带的垂直度不超过一定限度以保证皮带平稳地运行。
Idler is an important part of belt conveyor, which has many kinds and large quantity. The function is to support the belt, reduce the running resistance of the belt, and make the verticality of the belt not exceed a certain limit to ensure the smooth running of the belt.
托辊按其用途分类为调心托辊、缓冲托辊、槽型托辊、平行托辊。调心托辊的作用是纠正带式输送机的跑偏，通常输送机的重载段上安装回转式槽型调心托辊，空载段上安装平行调心托辊。缓冲托辊是根据实际情况应用于机尾架上的，受料时，可以降低物料对皮带的冲击，有利于沿长皮带的使用寿命。槽形托辊一般由两个侧托辊和一个平托辊组成，槽角度一般为30度，对于可拆卸式的带式输送机，槽形托辊的三个托辊互相铰接在一起，故称铰接托辊。平行托辊一般为一个长辊，它安装在承受压力的下端故称下托辊。
According to its application, idler can be divided into centering idler, buffer idler, trough idler and parallel idler. The function of the self-aligning idler is to correct the deviation of the belt conveyor. Generally, the rotary groove type self-aligning idler is installed on the heavy-duty section of the conveyor, and the parallel self-aligning idler is installed on the no-load section. The buffer idler is applied to the tailstock according to the actual situation. When receiving the material, it can reduce the impact of the material on the belt, which is conducive to the service life of the belt along the length. The troughed idler is generally composed of two side idler and a flat idler, and the groove angle is generally 30 degrees. For the detachable belt conveyor, the three rollers of the troughed idler are hinged to each other, so it is called the articulated idler. The parallel idler is generally a long roller, which is installed at the lower end under pressure, so it is called the lower idler.