Patent ID: 7325623

Claim:
A tillage tool comprising: a shaft supported for rotation about its longitudinal axis; and a series of coaxial spike wheels disposed along the length of said shaft for rotation therewith in unison about the longitudinal axis of the shaft in engagement with the ground, each of said spike wheels including as a part thereof a hub received on said shaft and a plurality of spikes projecting outwardly from said hub at spaced locations around the hub such that the hub and spikes are rotated together as a unit by the ground during advancement of the tool with the wheels in engagement with the ground, each hub having a pair of opposite ends abutting an end of the hub of the next adjacent spike wheel, the ends of adjacent hubs being provided with interengaging locating structure disposed to rotatively index adjacent spike wheels by a certain amount relative to one another, said structure including a notch on one hub and a projection on the adjacent hub matingly received within said notch, each hub having a notch at one end and a projection at the other end, said notch and said projection of each hub being circularly offset from one another by said certain amount whereby to correspondingly maintain adjacent wheels interlocked and circularly offset from one another during their rotation as a unit with the shaft and with one another during ground engagement.