as the top surface thereof as best seen in fig3 and 4 blade engaging and locking system 26 incorporates a blade locking and engaging arm 39 and a supporting plate 33 plate 33 is preferably permanently mounted to mould board 21 and locking and engaging arm 39 is pivotally secured to plate 33 in the preferred embodiment bolt 40 interconnects arm 39 with plate 33 while also assuring free pivoting movement of arm 39 about the axis defined by bolt 40 as is fully described below the free pivoting of arm 39 assures the quick and easy secure locking engagement of blade 23 in order to assure the secure locked retention of blade 23 in its engaged position arm 39 incorporates a locking hole 41 and plate 33 incorporates a similarly dimensioned axially aligned locking hole 45 when locking holes 41 and 45 are axially aligned bolt means 42 is inserted therethrough in order to assure secure locked retention of arm 39 in its blade engaged position as should now be clear from this discussion the blade locking and engaging system of this invention provides ease of installation and secure locked engagement of a plow blade using only a single bolt in the preferred embodiment blade support assembly 22 also incorporates a blade.