Abstract: The pneumatic greasing system for the fifth wheel of a semitrailer uses compressed air tanks to power a pneumatic grease pump delivering grease from a reservoir mounted behind the cab of the tractor to the fifth wheel. The pump is actuated by an electronic switch mounted on the gear shift lever controlled by the operator of the tractor-trailer rig, the switch energizing a solenoid mounted at the pump and reservoir. The grease is delivered to a grease manifold mounted at the anterior portion of the lower plate of the fifth wheel, from which it is distributed to multiple compartments constituting a grease pan installed on the bottom of the lower plate. Air pressure forces the grease from the compartments of the grease pan through a plurality of countersunk orifices in the lower plate. Longitudinal and rotational movement of the bearing surfaces of the upper and lower plates ensure a uniform distribution of grease in the fifth wheel.