Orders for medium-duty vehicles in Classes 5-7 maintained strength with a 14.2 percent increase in March from a year ago, ACT Research has reported.

Medium-duty orders have now recorded positive year-over-year gains for six of the past seven months. In March, orders increased to 20,800 units. Seasonal adjustment discounts March activity to 20,200 units, according to the report.

"All in all, the medium-duty market is progressing a little better than we expected, at least in the early part of the year," said Steve Tam, ACT's vice president for the commercial vehicle sector. "If history is any indication, we can expect orders to hold at this level for another month, then start to drop off meaningfully from May through July before picking back up in the last four months of the year."

March was also the first month in the past six in which orders of Classes 5-8 fell below 50,000 to 46,100 units, which represents a 0.9-percent increase from March of 2014.