Commutator motor

A non-commutating-pole commutator motor for driving a hand tool comprising:

• a) a field winding carried by poles of a laminated core stator which is mounted in a motor casing;
• b) a rotor winding attached to a commutator and having commutating coils, wherein the commutating coils of said rotor winding define a plane advanced around a longitudinal axis of said motor relative to a central plane lying in a center between opposite poles of said laminated core stator, and wherein the advanced plane is defined by the commutating coils and chosen such that, in one of two directions of rotation, good commutation is assured at full motor output;
• c) a brush apparatus non-rotatably secured in said motor casing and comprising brushes contacting diametrical points on said commutator;
• and
• d) switch means for reversing the direction of rotation, said switch means yielding a preferred direction of rotation in a first switch position and an opposite direction of rotation in a second switch position, and wherein said switch means applies a first number of turns of the field winding to said motor in the first switch position and a second number of turns of the field winding to an electric circuit of the motor in the second switch position, said first number of turns being less than said second number of turns;
• wherein said switch means comprises a double pole reversing switch, and said field winding comprises a first pair of coils and a second pair of coils;
• wherein said first pair of coils is connected to a main voltage and to an input side of said switch means, respectively;
• wherein said second pair of coils has one end connected to one of said brushes, and another end connected to an output of said switch means at a connection that lies in the electrical circuit of the motor when said opposite direction of rotation is chosen;
• and
• wherein two connections on an output side of said switch means, which lie in the electrical circuit of the motor when said preferred direction of rotation is chosen, are connected directly to the brushes, whereby there is an interchanged assignment of the brushes to the first pair of coils as compared to the assignment of the brushes for said opposite direction of rotation.