For most manufacturers, these are tractors that were built since the late 1960's. One manufacturer provides an approved ROPS and seat belt for their tractors that were built since 1939. Over the years, purchasers of tractors have expressed an interest in a second seat on the tractor to provide a functional location for instruction and diagnostic trouble shooting. All of the major manufacturers now provide this instructional seat, either as standard equipment or as an option for certain models of equipment with enclosed cabs. The seat is labeled as an Instructional Seat.
Manufacturers continue to warn against permitting extra riders on equipment.
This second seat is not for passengers and especially not for children. Children must not be permitted on equipment. During the 1990's, electronic systems took over much of the functional control of larger agricultural machines. For example, a tractor will have a hitch and transmission controller, possibly an engine controller and a computer to manage the GPS and other related systems. In some applications, when the tractor engine is started, switches and computer logic require that the transmission and PTO must be deliberately engaged and that the hitch does not move until the hitch control is moved.