A tine arm for an agricultural machine for working grass, hay or other crops on the field, wherein one or more tines are mounted on the time arm, the tine arm comprising: - a first arm part and a second arm part which are pivotally connected to each other between a working position and a transport position, and - a locking device configured to lock the first arm part with respect to the second arm part in the working position, wherein the locking device comprises: - a locking pin movably mounted on the first arm part between a locking position and a non-locking or releasing position, and - a first slot and second slot which are mounted on the second arm part, wherein the first slot is arranged to receive the locking pin in the locking position when the first arm part and the second arm part are positioned in the working position to lock the first arm part with respect to the second arm part in the working position, and wherein the second slot is arranged to receive the locking pin in the locking position when the first arm part and the second arm part are positioned in the transport position to lock the first arm part with respect to the second arm part in the transport position, wherein the locking device comprises a locking pin housing configured to receive the locking pin, wherein the locking pin is rotatable about its longitudinal axis, wherein the locking pin comprises a cam extending at least partially transversely to the longitudinal axis of the locking pin and wherein the locking pin housing comprises a cam surface configured to cooperate with the cam such that by rotation of the locking pin about its longitudinal axis the cam moves along the cam surface so as to move the locking pin from its locking position towards its non-locking position and/or from the non-locking position towards the locking position, characterised in that the locking pin housing comprises two spaced locking pin holders (22, 23), each locking pin holder (22, 23) having a locking pin receiving hole with an inner diameter substantially corresponding to an outer diameter of the locking pin, wherein at least one of the locking pin holders (22, 23) comprises the cam surface. - a first arm part and a second arm part which are pivotally connected to each other between a working position and a transport position, and - a locking device configured to lock the first arm part with respect to the second arm part in the working position, - a locking pin movably mounted on the first arm part between a locking position and a non-locking or releasing position, and - a first slot and second slot which are mounted on the second arm part, wherein the first slot is arranged to receive the locking pin in the locking position when the first arm part and the second arm part are positioned in the working position to lock the first arm part with respect to the second arm part in the working position, and wherein the second slot is arranged to receive the locking pin in the locking position when the first arm part and the second arm part are positioned in the transport position to lock the first arm part with respect to the second arm part in the transport position, wherein the locking device comprises a locking pin housing configured to receive the locking pin, wherein the locking pin is rotatable about its longitudinal axis, wherein the locking pin comprises a cam extending at least partially transversely to the longitudinal axis of the locking pin and wherein the locking pin housing comprises a cam surface configured to cooperate with the cam such that by rotation of the locking pin about its longitudinal axis the cam moves along the cam surface so as to move the locking pin from its locking position towards its non-locking position and/or from the non-locking position towards the locking position, characterised in that the locking pin housing comprises two spaced locking pin holders (22, 23), each locking pin holder (22, 23) having a locking pin receiving hole with an inner diameter substantially corresponding to an outer diameter of the locking pin, wherein at least one of the locking pin holders (22, 23) comprises the cam surface.