Abstract: The present invention provides a pumping system (60) comprising: a pumping mechanism (64); a motor (51) for driving the pumping mechanism; a drive control (50) for controlling the motor; and means (52) for monitoring at least one state within the system; wherein, to improve the performance of the system, the drive control causes the system to operate for transient periods in an overload condition which can result in said monitored state exceeding a predetermined operational limit, and when operating in said overload condition said drive control controls the power to the motor dependent on the level of said monitored state thereby avoiding said state from exceeding said operational limit.

Abstract: A vacuum pump comprises a rotor assembly mounted on a driven shaft, and a motor for rotating a drive shaft in forward and reverse directions. A driven member is located on the driven shaft and a drive member is located on the drive shaft for engaging the driven member to couple the driven shaft to the drive shaft. Each member has first and second impact surfaces. The members are configured to permit at least one quarter of a revolution of the drive member relative to the driven member in either the forward or the reverse direction before one of the impact surfaces of the drive member impacts upon a corresponding impact surface of the driven member. This can enable the drive member to acquire sufficient angular momentum before it impacts the driven member such that the amount of energy transferred to the driven shaft upon impact can be sufficient to free a pump that has become locked by process deposits.