Downhole drilling motors were first tested in the oil industry in 1873. These early motors had low power out put and did not deliver sufficient torque to operate rock bits effectively. In the early 1920's, turbo drill development projects were initiated in the United States and in Russia. Standard Oil Company of California began testing multi stage, axial - flow turbo drills which were the fore runners of those used today. At that time, the Russians worked on high - speed, single - stage turbines which utilized speed reducers to produce lower bit speeds. The Russians encountered many problems with the speed reducers in these high - speed turbines. Consequently, they switched to the low-speed multi stage turbo drills in the 1930's. By the early 1950's, the Russians had developed these turbo drills to the point where they were drilling 80 percent of their wells with them.