Abstract: A variable speed drive wherein a first embodiment is comprised of a pivotally mounted prime mover (10) coupled to a rotary fluid output device (58), such as a fan or pump, through a variable and fixed pulley drive arrangement (50 and 52) wherein the pivotal position of the prime mover (10) and accordingly the pitch diameter of variable pulley means (50) is controlled in accordance with fluid motor means (26, 28) coupled to the prime mover (10) and which is actuated in response to a fluid feedback control signal derived from a sensed output of the rotary fluid output device (58). The pivotal motion of the prime mover (10) imparts an arcuate motion to the variable pulley means (50) which effects a speed variation of the rotary fluid output device (58) in accordance with the variation of the pitch diameter ratio of opposing variable and fixed pulley means (50 and 52).

Abstract: An apparatus for supplying conditioned air at a substantially constant temperature and humidity. The apparatus includes a supply duct coupled to a source of supply air for carrying the supply air therethrough. A return duct is coupled to the supply duct for carrying return conditioned air therethrough. A temperature reducing device is coupled to the supply duct for decreasing the temperature of the supply and return conditioned air. A by-pass duct is coupled to the supply duct for selectively directing portions of the supply and return conditioned air around the temperature reducing device. Another by-pass duct is coupled to the return duct for selectively directing portions of the return conditioned air around the supply duct and the temperature reducing device.