Abstract: A turf aerator (11) provided with a reciprocating drive mechanism (33, 37) to repeatedly drive a leg (35) carrying a tine (31) vertically into the ground (52) and retract it again at regularly spaced intervals, the tine leg (35) being substantially rigid and pivotally mounted at its upper end (36) to a drive assembly (33). The tine leg (35) is provided with a cam surface (160) in the forward direction and a forward guide arrangement (141) including a forward travel limiting stop, acting on the cam (160), to limit forward travel of the tine leg (35) and thereby maintain a substantially vertical travel path for the leg (35).