Alan Riach
New User
The cause of rearing up in any tractors is to do with the position of the drawbar above the ground (strictly speaking above the point where the tire contacts the ground) and nothing to do with its position relative to the axle.
The two points of application of force on the tractor are 1. where the wheel touches the ground (it is nothing to do with the position of the axle) and 2 the point where the load is applied to the drawbar. These two forces apply a turning (or rearing) moment on the tractor. If the drawbar is kept close to the ground the rearing moment is kept low. When 3 point linkage tractors appeared one of the really dangerous tricks was to attach a chain to the top link attachment when pulling out tree stumps etc.(very high drawbar -very high rearing moment - very quick overturning). However Harry Ferguson's 3 point linkage system was the greatest advance in preventing rear turn over accidents that could be made
The confusion of thinking that the position of the axle effects the rearing moment is long held. Imagine the mechanical rotating parts are all welded solid and a magical force is applied where the tire contacts the ground to get the true story. Maybe thinking of a crawler helps - force is applied to tractor where the tracks contact the ground. Of course the force has to get into the tractor frame via the axle bearings but it is the point where the world contacts the tractor (at the ground (and at the drawbar) that is important.
The two points of application of force on the tractor are 1. where the wheel touches the ground (it is nothing to do with the position of the axle) and 2 the point where the load is applied to the drawbar. These two forces apply a turning (or rearing) moment on the tractor. If the drawbar is kept close to the ground the rearing moment is kept low. When 3 point linkage tractors appeared one of the really dangerous tricks was to attach a chain to the top link attachment when pulling out tree stumps etc.(very high drawbar -very high rearing moment - very quick overturning). However Harry Ferguson's 3 point linkage system was the greatest advance in preventing rear turn over accidents that could be made
The confusion of thinking that the position of the axle effects the rearing moment is long held. Imagine the mechanical rotating parts are all welded solid and a magical force is applied where the tire contacts the ground to get the true story. Maybe thinking of a crawler helps - force is applied to tractor where the tracks contact the ground. Of course the force has to get into the tractor frame via the axle bearings but it is the point where the world contacts the tractor (at the ground (and at the drawbar) that is important.