Paccar Inc. said today that its quarterly earnings more than tripled, thanks to pre-buy demand that took place before new federal emissions standards took effect. However, the company said orders for the next two quarters could be "unfavorably impacted" as fleets take a wait-and-see approach to trucks powered by post-October 1 engines. The truckmaker reported third-quarter net income of $128.9 million compared with $39.4 million a year earlier. Sales rose to $2 billion from $1.5 billion. Paccar, the parent company of Kenworth Truck Co. and Peterbilt Motors Co., said its North American production rates increased more than 60% in the quarter because fleets were skeptical about buying trucks with post-October 1 engines. The company added that revenue for its financial services segment fell to $110 million from $112 million although its pretax income almost tripled to $22.6 million from $8.2 million.