Abstract

Disclosed is a refractor of the type having a housing which has patient eye position for viewing along a sight axis extendible therethrough, a pair of superimposed cylinder lens assemblies, means for positioning a particular lens in front of the sight axis, axis control means for controlling the axis of each cylinder lens, a cross-cylinder assembly which is synchronously coupled with said cylinder lens assemblies. The improvement of such type of refractor comprises the positioning means including an internally threaded cylinder axis drive gear having a lock shaft, said gear located outside of the housing and having its lock shaft extending through an opening in the housing coincident with the common axis of both carriers, said shafted cylinder axis drive gear riding upon bearing means disposed between it and the housing. The housing opening for the lock shaft has a sleeve within the housing which circumscribes the opening. There is an annular space formed between the lock shaft and the sleeve. The sleeve retains a first bearing means followed by a first said carrier, the shaft of a shafted cell drive gear then fitting between the annular space formed between the sleeve and the lock shaft and locking onto said lock shaft for synchronous movement of said cell drive gear and said axis drive gear. Bearing means then are fitted between the cell drive gear and the first carrier. A second carrier then fits over said lock shaft with bearing means disposed between the second carrier and the cell drive gear. A threaded pin then screws into the internal threads in the lock shaft to secure both cylinder lens assemblies to the housing.