Total U.S. commercial trailer net orders fell 2% in July from June levels, according to ACT Research. Orders have fallen now for four months in a row.

When combined with solid trailer production volume during July, the decline in net orders resulted in industry backlogs slipping 4% month-over-month. Industry backlog, which ended the month at 93,600 units, closed July up 97% on a year-over-year basis.

"Given the industry's normal seasonal business patterns, the pace of orders is expected to slow further in the third quarter," said Frank Maly, director CV Transportation Analysis and Research with ACT.

Order volume should begin to build again during fall and winter, he said. Cancellations continue to be low, which denotes a solid backlog and is a positive indicator for the rest of the year and 2012.