A tipping mechanism for buckets carried by a conveyor or elevator. Each bucket 28 is attached to a chain 26 by a swing link 29 and each bucket carries a sector shape cam 30. As the buckets are carried around a sprocket 27 the cam 30 contacts a peg 31, so as to cause the bucket to progressively tip and empty. The movement of the buckets back to their horizontal position is fully controlled and is smooth by virtue of the contact between a French curve on the cam 30 and a cam surface 35 of substantially wedge shape located above or below the conveyor or elevator chain.