A scrum machine, or scrummaging machine, is a padded, weighty device against which a pack of rugby football forwards can practice scrummaging, and rucking. The ideal engagement of a pack into a scrum is a simultaneous movement in the hit, shunt and drive. It is the instantaneous force exerted that makes the difference not the sum of all the forces over time. Even small packs that co-ordinate in this fashion and hit 'on the beat' can control their scrums consistently. The purpose of the scrum machine is to provide teams with a safe tool with which to improve the strength and skills of their players.