A system is provided for sensing the presence of a semi-tractor as the mechanical connection between a trailer and a fifth wheel of the semi-tractor is made, or for sensing the presence of a rail car as the mechanical connection between the trailer and a stanchion plate of the rail car is made. The exercise device has a self-standing framework that includes a vertical post. An incentive pool is determined from previous patient claims and payments made to physicians in advance, such as in a base year. These features include a power take-off timeout, automatic fail-safe brake, and customized drive characteristics. The clock generator circuit may also include voltage-controlled delay cells that generate sets of clock signals delayed from one another by a non-overlapping time. The method utilizes a cable reel that features a power receptacle into which a cable connector can be easily plugged and unplugged.