Trinity Industries (NYSE:TRN) continues to hurtle along with robust revenue and earnings growth in its second quarter. The diversified manufacturer's momentum still looks strong, but with recent indications that the economy is slowing, it might be best to take a cautious approach.

Revenue for the quarter surged 23% to $883.8 million, the highest quarterly revenue in the company's history. Growth in earnings per share from continuing operations were even more explosive, coming in at $0.79 versus $0.27 in the same period last year, although the latest quarter's results include a $0.09-per-share gain from a property sale.

Trinity's CEO indicated that the firm was operating at close to full steam in the quarter, and this was reflected in the company's operating performance. Operating margin hit 11.9% in the quarter, up from 9.7% last quarter and more than double the 5.8% margin Trinity recorded in the same period last year.

For now, the firm looks well positioned to keep its manufacturing lines humming and its margins high. Backlog in Trinity's Rail Group (which, with 57% of operating earnings in the latest quarter, is the firm's largest unit) rose by 3,700 cars to 29,320 units. That means Trinity currently has over a year of backlog based on this quarter's shipment rate of 6,233 cars.

Even so, Trinity's order rate is worth monitoring, given its several quarters of breakneck growth and recent indications of a slowing U.S. economy. Last quarter, its order rate hit an all-time high of 12,941 cars. The latest quarter's haul of 10,012 cars, while still impressive, represents a significant slowdown compared to last quarter.

As Trinity notes in its regulatory filings, the railcar business is a cyclical one, and it's possible that the latest cycle has peaked. Trinity is not in danger of crashing, but now might not be a good time to jump on the train.

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Fool contributor Brian Gorman does not own shares in any the companies mentioned.