MACK issued a recall on multiple vehicle models

On certain school and transit buses, the Parker single check valve (SCV) that connects with the supply port of the Bendix SR-7 spring brake modulating valve may become excessively worn and eventually break apart. Pieces of the Parker SCV can become lodge inside the SR-7 valve, possibly causing either leakage out of the SR-7 valve or preventing air from properly exhausting from the SR-7 valve. This condition can cause a delay in the application of the parking brakes, the spring brakes not fully releasing or loss of isolation between the primary and secondary circuits. These conditions can occur without warning, leading to unintended vehicle rollaway, brake drag, or in case of loss of primary circuit, inability to modulate the spring brakes. An unattended roll away vehicle could strike a bystander or cause property damage. Correction: Dealers will replace the single check valve (SCV).