Abstract: A small portable motorized attachment for propelling portable scaffolds from place to place is provided comprising a pair of electrically operated propulsion units adapted to detachably replace the front caster wheels of a scaffold and a control means for operating the units, each unit comprising a base having a propulsion wheel operatively connected to a friction drive means and a motor swingably cantilevered from the base with the weight of the cantilevered assembly pressing a gear driven friction drive wheel into engagement with the propulsion wheel so that the units when stably connected with one another in place on the scaffold act in unison to brake, clutch and propel the scaffold.