Orders of medium-duty vehicles in classes 5-7 bounced back from a weaker July with a 10 percent increase but fell year-over-year, according to ACT Research.

Medium-duty orders reached a preliminary number of about 17,500 units for trucks, RVs, and buses in those classes. Orders were down 3 percent compared to the same month a year ago.

"Historically, August is an above average order month for medium-duty vehicles, so seasonal adjustment actually reduces August’s medium-duty order volume to 17,200 units," said Kenny Vieth, ACT's president and senior analyst.

Meanwhile, Class 8 orders fell sharply in August for a 20 percent decline from July and 22 percent lower than August of 2014.