A mower frame unit is operatively connected with a tractor device and the mower frame is moveable between a generally horizontal first position and a generally vertical second position. The mower frame is moveable from the first position to the second position via a hydraulic cylinder and piston assembly carried by the mower frame to pivot the mower frame about a transverse axis. The mower frame carries a tensioner assembly that is operatively connected to a lock assembly. The tensioner assembly serves at least two purposes. Namely, to tension a belt operatively connected to mower blade and to maintain a portion of the lock assembly in a locked manner when the tensioner assembly is in a state of tension.