Abstract: A three cone rock bit comprises legs and freely rotating cutters mounted on the same. The angle .alpha. between the projections of the rotational axes of two adjacent cutters on a plane perpendicular to the axis of the bit is more than 120.degree. but less than 170.degree.. A flow nipple to supply drilling fluid is provided in the bit, the outlet thereof being positioned between said two cutters.

Abstract: A turbodrill whose body accommodates a thrust bearing taking the reaction of the bottom hole, said bearing carrying a shaft built up of separate consecutively-connected sections and mounting the turbine rotors which create a torque and a hydraulic load and transmit them to the shaft wherein, according to the invention, there is an additional thrust bearing installed on the shaft between the main thrust bearing and the turbine rotors and taking the hydraulic load and a mechanism installed on the shaft between said thrust bearings and intended to transmit torque from one shaft section to the other and capable of elastic deformation owing to which it relieves the additional thrust bearing from the hydraulic load and transmits the latter to the thrust bearing which takes the reaction of the bottom hole.The turbodrill according to the invention makes it possible to use the thrust bearing taking the reaction of the bottom hole until said bearing is completely worn down.