MASS production methods in the construction of modern aircraft demand far‐reaching standardization of such component parts as can be used in various types of aeroplane. Such standardization has, for instance, been applied to the power plant control rods of the Ju 52 where a unified design of welded steel levers is found together with standardized shafts. That type of construction has given very satisfactory results on the whole though improvements have been made here and there to keep abreast of the general advance in aircraft design and of the development of fabricating methods. The standardized rigging thus evolved responds to practical requirements in that the number of parts has been reduced to a minimum so as to allow of a maximum of combinations and to cut down the number of spares to be kept in store. Such demands were chiefly made by the German Air Force since interchangeability of parts is, of course, a factor of primary importance to ensure simplification of supply services and ease of maintenance of the first line fleet in case of an emergency. Moreover, plain bearings for moving parts had proved unsatisfactory in service as they necessitated frequent inspection and lubrication. The only way out of that difficulty was to employ ball bearings through‐out to reduce friction to an absolute minimum and to eliminate lubrication altogether.