Ụkpụrụ ọrụ nke igwe mbuli ịwụ dịtụ mfe. Nnukwu ihe na-abanye n'ime nchịkọta nchịkọta na ala nke igwe na-ebuli ịwụ, na moto na-eme ka onye na-eme ihe na-ebugharị sprocket ma ọ bụ kwọọ drum ka ọ gbanwee. Dị ka ụkpụrụ esemokwu si dị, drum na-akwọ ụgbọala na-eme ka onye na-ahụ maka traction (ajị anụ ma ọ bụ eriri traction) gbanwee, na bọket ahụ etinyere na traction so na-ekpochapụ ihe site na nchịkọta nchịkọta wee bulie ya na onye òtù traction ahụ n'elu igwe na-ebuli bọket. Mgbe ahụ, ịwụ ahụ na onye òtù traction dị n'akụkụ elu nke ịkwọ ụgbọ ala iji tụgharịa ala, budata ihe ahụ, tụfuo ihe ahụ n'ime ebe a na-ekpofu ihe ma wepụ ya n'ọdụ ụgbọ mmiri. A na-atụgharị bọket na-ekpu ihe iji nweta ibuga ihe na-aga n'ihu.