In the MX25, MX50 and MX80, the apron speed adjustment is actually a ratchet mechanism, which changes the amount of apron chain travel between clicks. Longer apron chain travel, which is consider the Fast setting, increases the amount of manure fed to the beater bar, thus increasing the amount of manure spread per pass. Shorter apron travel, which is considered the Slow setting, reduces the amount of manure fed to the beater bar, and thus the amount of material spread per pass.
In the MX130, speed adjustment is accomplished with a 3-speed gearbox which changes the apron speed. The Fast setting increases the amount of manure fed to the beater bar, thus increasing the amount of manure spread per pass. The Slow setting reduces the amount of manure fed to the beater bar, and thus the amount of material spread per pass.