Donald D Schwellenbach: LaValle D Ptak, April 21, 1981: US04262549 (172 worldwide citation)

A variable mechanical vibrator includes a first eccentric weight fixed to a rotatably mounted shaft. A second eccentric weight is rotatably mounted on the shaft, and the two weights are rotated together under control of mating engagement abutments, one carried by the shaft and one carried by or comp ...

Eugene E Crile, Donald D Schwellenbach: Molding machine with vibration isolation. LaValle D Ptak, December 9, 1980: US04238177 (27 worldwide citation)

A concrete block molding machine has the pallet support table mounted on the main frame of the machine through pneumatic tires which provide vibration isolation between the pallet support table and the main machine frame. A mold, having vibrating mechanism mounted on it is lowered into position on p ...

Michael E Coggin, Charles K Everett, Donald D Schwellenbach: Pallet scraper. LaValle D Ptak, January 31, 1984: US04428090 (12 worldwide citation)

A pallet cleaning device used to clean pallets moved from a pallet magazine or supply hopper to the molding section of a concrete block molding machine includes a frame for mounting the pallet cleaning device directly in front of the pallet magazine of the block making machine. A first sub-frame is ...