A tractor unit mounting mechanism includes a clamping assembly that is configured to engage and disengage a tractor unit to a guide track. The guide track includes a first rail and a second rail. The mounting assembly also includes at least one pivot block set that has a first pivot block and a second pivot block. Each of the first pivot block and the second pivot block includes a first rolling device and a second rolling device. When the tractor unit is in a disengaged position, a first distance between an outer portion of the first rail and an outer portion of the second rail is greater than a second distance between the first rolling devices of the at least one pivot block set, and the first distance is less than a third distance between the second rolling devices of the at least one pivot block set.