The limbers were manufactured by the Maxwell Motor Car Co., which had orders to turn out 2,575 of them. The first deliveries of limbers came in September, 1918, and seven a day were being turned out in October, a total of 273 having been completed by the day of the armistice. A month later the number of completed limbers totaled 587. It was in the making of the recuperator systems that the greatest problems were presented. No mechanism at all similar to this had ever been made in this country. No plant was in existence here capable of turning out such a highly complicated, precise, and delicate device. Finally, after much Governmental search and long negotiation, the Dodge Bros., of Detroit, motor car builders, agreed to accept the responsibility. In this effort they built and equipped the splendid factory, costing $10,000,000, described elsewhere. This howitzer recuperator is turned out from a solid forging, weighing 3,875 pounds, but the completed recuperator weighs only 870 pounds. Each cylinder must be bored, ground, and lapped to a degree of fineness and accuracy that requires the most painstaking care. Difficulties of almost every sort were experienced with the forgings and other elements of the recuperators. The steel was analyzed and its metallurgical formulas were changed. The work of machining proceeded favorably until the very last operation--that of polishing the interior of the long bores to a mirrorlike glaze and still retaining the extreme accuracy necessary to prevent the leakage of oil past the pistons. Such precision had been theretofore unknown in American heavy manufacture. Until the many processes could be perfected, the deliveries were held back. Even with the delivery of the first recuperator, difficulties did not vanish. This mechanism has no adjustments which can be made on the field, but depends for its wonderful operation upon the extreme nicety of the relation of its parts. It required the alteration of certain small parts before the first trial models could be made to function. However, all obstacles and difficulties were finally overcome, and in the plant that had been erected during the bitter cold of one of our severest winters, and with practically entirely new machinery and workmen, production got under way, and the first recuperator was delivered early in July, 1918, nine months after the contract was signed. Production in quantity began to follow shortly after that month, and by November an average of 16 recuperators a day was being turned out. Of the 3,120 recuperators contracted for, 898 had been finished when the armistice was signed, and this quantity was increased to 1,238 one month later.