Casters thiab log yog siv rau ntawm cov khoom siv xws li rooj tog zaum, tshuab, lossis lub laub kom tso cai rau cov khoom siv yob thaum nws yuav tsum tau txav los yog hloov chaw. Lawv txo qhov kev siv zog uas nws yuav siv los txav cov khoom siv. Cov casters txhua tus muaj lub log uas tau nruab rau ntawm lub qag thiab txuas nrog lub phaj, qia, lossis lwm yam khoom sib dhos uas txuas rau cov khoom siv. Cov log muaj ib lub qhov nyob rau hauv nruab nrab thiab mount rau lub axles los yog spindles ntawm casters, wheelbarrows, thiab lwm yam khoom siv-kuav khoom.