Stauffer Tell-tale Lubricator

Stauffer Tell-tale Lubricator, type B, no.5, in section

This well-known fitting, for supplying solid lubricant to a bearing, was patented in 1878 by Mr. B. Stauffer. The cup for containing the lubricant (a sample of which is shown in a glass jar) is screwed internally to fit a disc formed with the nipple screwing into the bearing. Upon slightly turning this cup, or cap, some of the grease is forced into the bearing and in this way the lubricant is supplied at intervals while its viscosity prevents its flowing away. In a later form, which is shown in section, there is a small spring-loaded piston on the cap, which gives a continuous supply and indicates when the cap requires to be screwed further home; the rate of feed is adjustable by an internal set screw which contracts the delivery passage.