Abstract: A machine for uniformly applying a pressure on a relatively flat surface includes a portable frame structure and at least one frame supporting roller rotatably mounted on an axle by a pair of spaced journal assemblies. Each journal assembly has an upright bracket member with a top end secured to the underside of the frame structure, and an upright guideway in which the body portion of a bearing member, for rotatably supporting one end of the roller axle, is guidably movable. Flanges laterally extended from opposite sides of each bearing body portion are positioned between an associated bracket member and adjacent side of the roller. Each flange is formed with a fulcrum portion that is in contact engagement with the adjacent side surface of an associated bracket member for pivotal movement of the bearing member in response to a lateral tilting movement of the roller.