Friction kelly bar derives its name from the means by which it transfer torque to the drilling tool. The telescopic elements are advanced by using the “frictional contact” from each of the friction drive rails that run down the outside of each kelly bar. These drive rails, on the outside of each kelly bar, are driven by the rotary table and the terminal joints of each successively larger diameter kelly bar. The terminal joint is long piece on the inside and at the bottom of each kelly bar. Friction kelly bars are normally supplied in 4 or 5 telescopic elements as they are mostly used for deep piles in medium hard soil conditions.