Abstract: Power transmission gearing has two countershafts both of which are mounted with virtually no capability of axial movement and drivably connected to a common driving shaft and a common driven shaft by gearing. The gearing which connects the countershafts to the driven shaft conprises a single helical gear of one hand on one of the countershafts, a single helical gear of the other hand on the other of the countershafts, and a double-helical gear assembly on the driven shaft, one toothed zone of the doublehelical gear assembly meshing with one of the single helical gears and the other toothed zone of said assembly meshing with the other of said gears. The double-helical gear assembly is capable of axial movement on the driven shaft to equalize the torque transmitted by each countershaft.

Abstract: An optical system in which individual connections are made involving the passage of light between a specific device in one array of optical devices and a specific device in another array of optical devices includes a phase halogram plate of the transmission type fixed relative to each array.

Abstract: Coagulation apparatus for producing thick microporous polyurethane sheet material by passing a layer of polymer solvent composition beneath a close spaced plate with liquid non-solvent fed to the gap between the plate and the surface to produce controlled initiation of the coagulation.