C. S. Johnson Company, a Corporation v. Merle W. Stromberg, Doing Business as California Batching Equipment Co.

This is a suit for infringement of United States Letters Patent No. 2,138,-172, for a concrete Batching Apparatus invented by plaintiff’s assignors. The patent issued November 29, 1938, expired November 29, 1955. (The filing date was February 10, 1937.) Suit was instituted August 25, 1954. By the time trial was had, the prayer for injunctive relief was moot.

The invention may be succinctly described as a combination patent, whereby a cement hopper is centrally located within an aggregate (sand and rock) hopper, each hopper being independently supported so that their contents can be separately weighed, with the respective hopper discharge gates being so concentrically located that the cement is discharged simultaneously (or nearly so) with the aggregate, by gravity, through the center of the “flowing shaft of aggregate,” while water is supplied to the aggregate by a tubular stream sur rounding the aggregate. The simultaneous fall causes a certain amount of “commingling,” prior to the batch reaching the pre-mix truck or mixer. If no water is added, a dry batch is, to a certain extent, “commingled.”

By such a procedure, various advantages are claimed: (1) a reduction in the amount…