The Collaborative International Dictionary of English v.0.48:

Truckman \Truck"man\, n.; pl. Truckmen.
   1. [From Truck barter.] One who does business in the way of
      barter or exchange.
      [1913 Webster]

   2. [From Truck a carriage.] One who drives a truck, or
      whose business is the conveyance of goods on trucks.
      [1913 Webster] Truculence