After rising for two months, purchasing demand for power transmission and motion control products fell off this summer, according to latest figures available from the Power Transmission Distributors Association in Chicago. U.S. distributor sales dropped 7% from June to July. Still, year-to-year comparisons remain positive for sellers for the first half, with sales coming in 11% higher in July 2007 compared to the same month a year ago. Buyers are purchasing fewer unmounted bearings, mounted bearings and mechanical drives systems. Demand is up, however, for standard industrial motors and variable speed drives.