High demand in heavy duty truck engines lifted Cummins' earnings nearly 8% in the second quarter. Profit came in at $2.43 a share, that's almost a quarter better than a year ago. Sales were strong. They rose about 7% to more than $4.8 billion, which was slightly better than expectations. Sales of heavy duty truck engines jumped 10% globally and North America did the best among all regions. Cummins saw revenue climb 14%. CEO Tom Linebarger said, "Demand is growing in on-highway markets in North America this year as the economy improves and we have gained market share in medium duty truck and bus." Sales outside of North America, however, stayed nearly the same. Low demand from Brazil and India offset the strong performance in China. TheStreet's Julia Sun reports from New York.