Abstract: A pump with a canned motor (1) comprises a hollow shaft (4) open at the ends (5, 6) and provided with shaft ends (7, 8) and made of a relatively thin-walled tube. The portions (7, 8) of the shaft (4) are of a reduced diameter (d.sub.1, d.sub.2). A reciprocating ball (12) is situated in the cavity between a first shaft portion (8) and a second shaft portion (7), said first shaft portion forming a shaft end and provided with a spline (17). This ball abuts seats (13, 14) resulting from the reduction of the diameter of the shaft portions (7, 8), whereby the ball (12) and the seats (13, 14) form a valve. In this manner the valve of the hollow shaft (4) is provided in a particularly simple manner as the seats (13, 14) can be provided simultaneously with the manufacture of the shaft portions (7, 8) of a reduced diameter. The shaft portion (8) carrying the impeller (10) is provided with a spline which provides the hollow shaft (4) with the necessary torsional strength.

Abstract: An electric motor comprising a motor overload protection such as a thermal switch and a main relay for controlling a multipolar switch in the voltage supply conductors of the motor. The thermal switch and the main relay are mounted in a control circuit in parallel with the voltage supply conductors. An auxiliary relay is coupled in parallel with the main relay and can connect an auxiliary motor via a contact arm when the thermal switch is switched off.