1) Two examples of the noun have been recorded in coal-mining contexts, one in the inventory of Charles Best of Landimer in Shelf.
1700 three Tuggs and three shovels and the other in the accounts of Farnley colliery: 1716 Tuggs 5. The reference may be to ‘the iron hoop of a corf’, possibly a sort of handle. In farming records it was part of the harness of working horses, a short chain attached to the hames: 1570 foote shackelles ... one payer of tugges and sex payer of cutwithes
c.1742 tug for swingletree, Holmfirth.