Abstract: An apparatus for sealing a door of a chamber, the chamber being of the type wherein the door is urged into engagement with the chamber upon rotation of a locking wheel and having a seal positioned between the door and the chamber such that upon movement of the door toward the chamber the seal is compressed, comprises a motor for providing torque to the locking wheel for urging the door toward the chamber. A current source supplies current to the motor. A circuit monitors the current supplied to the motor to determine if a desired degree of pressure between the seal and the chamber has been achieved based on the amount of current drawn by the motor. The current source is responsive to the monitoring circuit so as to end the supply of current to the motor when the desired degree of pressure is achieved.