This specification covers the design and rating of the following: a. Pumping-unit structure. b. Pumping-unit gear reducer. c. Pumping-unit chain reducer. Nothing contained in this specification is to be construed as granting any right, by implication or otherwise, for manufacture, sale, or use in connection with any method, apparatus, or product covered by letters patent, nor as insuring anyone against liability for infringement of letters patent. This specification is for the convenience of purchasers and manufacturers in ordering and producing pumping units and is not intended to inhibit purchasers and producers from purchasing and producing pumping units meeting specifications other than those contained herein nor is it intended in any way to inhibit purchasers from purchasing pumping units from companies not authorized to use the API monogram.