1927 - Over the years there have been few Mack models as famous as the AC model. The Mack BJ and BB models, the first of the "early B Series" introduced in 1927, represented the company's first trucks developed in response to the demand for larger capacity, higher speed haulage. The growing acceptance of trucking as a transport mode required the application of new design and engineering principles, and a variation of sizes and weights to satisfy emerging state regulations. More than 15,000 units were built through 1941.
Mack pioneered the use of power brakes on trucks by using a vacuum-booster system.
1929 - 1944 - During the years from 1929 until 1944, Mack produced 2,601 semi- or full trailers.
Full trailers were of two styles, non-reversible or reversible. Non-reversible trailers had a solidly fastened rear axle arrangement with a draw bar on the front end so that the trailer could be drawn in one direction.
A reversible trailer has axle arrangements similar at each end. Either end could be fastened in a stationary position while the draw bar could be fastened to the other end of the trailer. In this way, either end could be the front of the unit.