API Standard Drilling Mud Pump Power End Parts Pinion Shaft For oilwell drilling Pinion shaft is a very important part of power end of mud pump. It works together with the big gear ring transfer the power to the mud pumps from the power unit. In order to ensure its quality, we use 40CrMnMo alloy steel forging material to manufacture it. And due to the high precision CNC grinding machine we use, the accuracy of its gear could be ensure. Pinion shaft is an alloy steel forging.