Caterpillar Thursday reported a decline of 50 percent in worldwide machinery sales for the three months ending in October. The world's largest construction manufacturer said sales for the three month period in North America were down 58 percent since last year while sales in Europe, Middle East sales were down 41 percent while Asia Pacific sales were down 39 percent from the same period a year ago. Engine sales , according to a company release, dropped 30 percent from a year ago.