Temperature-gradient gel elec-trophoresis of nucleic acids: analysis of conformational transi-tions

A conveyor has wheel engaging rollers which operate over a wheel path and engage the peripheries of vehicle wheels from behind so as to move the wheels and vehicles along the path. The rollers also move over the path when returning to their starting positions, and they drop into depressions at their starting and terminal positions so as not to obstruct the passage of vehicle wheels over them. Fluid operated cylinders propel the wheel engaging rollers in both directions along the path.