The sheep foot roller is also a vehicle similar to smooth wheel rollers. However, in contrast to a smooth drum used in smooth wheel rollers, these machines have a sheep’s foot or tamping roller in front. While on the rear side, they have tyres.
Sheep’s foot or tamping roller consists of a hollow steel cylindrical drum made with steel projections or feet extending in a radial direction on front. These projections of feet are extended outward from the cylinder surface.
The dimension of the roller can be varied to get different soil compaction capacities. These dimensions include the diameter and width of the drum and length and shape of the feet of the rollers. Usually, the feet are 15 to 20 cm long and placed in staggered row around the drum. This allows to obtain a contact of about two tamping feet per square foot of tamped area. The weight of the drums can also be varied in a way similar to smooth wheel rollers.
Sheep foot rollers are particularly suitable for cohesive soils. This is due to smaller width of loaded areas under their feet. Sometimes sheep foot rollers are also employed in pre compaction phase on the areas with slabby soil fragments of rock soils. The break down these soft rock fragments. They are also used to pulverize hard dry soil and can also help in mixing of soils.
Sometimes, these rollers are also towed by a tractor. This also allows a compaction through vibration. Especially in sandy soils, mixing large quantities of water and using a towing tractor will couple the benefits of vibrations to achieve much better compaction.