1 Connecticut Children's Medical Center-Volunteer opportunities are available for anyone who is 13 years old, dependable, and able to commit to at least three hours of service per week for a minimum commitment of one year (six weeks during the Summer period). Children's Hospital Central California-We can match your skills and interests with a volunteer position that meets your needs and ours! 2  Whether it's playing with children in the Child Life Playroom, visiting with family members, or providing clerical support in an office setting, you can make a difference.
Definition of tractor - a powerful motor vehicle with large rear wheels, used chiefly on farms for hauling equipment and trailers. Definition of tractor - a powerful motor vehicle with large rear wheels, used chiefly on farms for hauling equipment and trailers.
In common parlance, then, a semi is a tractor pulling a semi-trailer. The most common tractor-trailer configuration in North America is the 18-wheeler semi. The tractor has a front axle with two wheels, and two rear axles with four wheels each, for a total of 10. The trailer has two rear axles with four wheels each, for a total of eight.