Multi-speed drive with forward/reverse lockout

A floor maintenance vehicle comprising, in combination, a body, a plurality of wheels for supporting said body, means for steering said vehicle, means for maintaining floor surfaces, a plurality of reversible electric drive motors for driving said wheels, said motors each having an armature and a field coil, a power source for supplying current to said motors, means for controlling the current applied to said motors providing increasing and decreasing stepwise increments, means for switching said controlling means from one current increment to the next;

• said controlling means including means for providing resistance and means for shunting said resistance means, said resistance means being in series with said motors and means for selectively changing the electrical connection of said motors with each other from series to parallel and from parallel to series, means for delaying application of said current increment until said vehicle has attained acceleration in forward velocity, and means for preventing reversing direction of said motors until said vehicle has slowed to a predetermined speed, circuit means for reversing the flow of current through said field coils to reverse the direction of the motors, and a circuit for sensing the rotation of at least one of said motors in a coasting state wherein said at least one motor is rotating without voltage applied to said field coil and means for preventing the application of voltage to said field coils which would reverse the direction of said motors until said at least one motor has slowed to a predetermined rotational velocity, said circuit including;
• detecting means connected in parallel with the armature coil of said at least one motor with one side of said armature coil and one pole of said detecting means being at ground potential for detecting voltage generated therein when said at least one motor is in said coasting state, and preventing means responsive to said detecting means for preventing application of said reversing voltage to said motors while said detecting means is sensing said generated voltage.

A floor maintenance vehicle comprising, in combination, a body, a plurality of wheels for supporting said body, means for steering said vehicle, means for maintaining floor surfaces, a plurality of electric drive motors for driving said wheels, said motors having field and armature coils with one side of said armature coils at ground potential, a power source for supplying current to said motors, means for controlling the current applied to said motors, said controlling means being adapted to provide stepwise increasing and decreasing increments, means for switching said controlling means from one current increment to the next, means for delaying application of said next current increment until said vehicle has had some time to accelerate, means for selectively changing the electrical connection between said motors from series to parallel and from parallel to series, means for reversing the flow of current through said field coils for reversing the rotation of said motors;

• and a control circuit for sensing rotation of at least one of said motors, said control circuit serving to prevent application of electrical power to said motors until said at least one motor has slowed to a predetermined rotational velocity, said control circuit including a transistor having a base and an emitter, said base being connected to the ungrounded side of said armature coil and said emitter being at ground potential.

A riding type floor maintenance vehicle comprising a vehicle body including an electric motor, said body being supported on a plurality of wheels, at least one of said wheels being drivenly connected to said electric motor, said motor being electrically reversible, said vehicle including a control circuit for sensing rotation of said driven wheels and means for preventing the application of electrical power to said motor to reverse said motor until said wheels have slowed to a predetermined rotational velocity, said control circuit including a first control circuit for applying current to said motor causing said armature to rotate in a first direction;

• and a second control circuit for applying current to said motor causing said armature to rotate in a second direction being opposite to said first direction;
• said preventing means comprising a first normally closed relay contact in series with said first circuit, and second normally closed relay contact in series with said second circuit;
• a first holding circuit means controlling said first relay contact, a second holding circuit means controlling said second relay contact;
• means for detecting said generated voltage;
• preventing means being responsive to said detecting means for preventing completion of said first circuit when said armature is rotating in said second direction and for preventing completion of said circuit when said armature is rotating in said first direction;
• said first holding circuit means being responsive to said detecting means for holding said first relay contact in its open-circuit state until said armature has slowed to said predetermined speed when said armature is coating in said first direction;
• said second holding circuit means being responsive to said detecting means for holding said second relay contact in its open-circuit state until said armature has slowed to said predetermined speed when said armature is coasting in said second direction;
• and wherein said second holding circuit means includes a first relay coil for controlling said second relay contact;
• a third relay contact responsive to said first relay coil and being in series with said first relay coil;
• a fourth relay contact in parallel with said third relay contact;
• a second relay coil in series with said first control circuit for controlling said fourth relay contact;
• and wherein said first holding circuit means includes a third relay coil for controlling said first relay contact;
• a fifth relay contact responsive to said third relay coil in series with said third relay coil;
• a sixth relay contact in parallel with said first relay contact;
• and a fourth relay coil in series with said second control circuit for controlling said sixth relay contact.

An electrically driven riding vehicle comprising a vehicle body including an electric motor, said body being supported on a plurality of wheels, at least one of said wheels being drivenly connected to said electric motor, said motor being electrically reversible, said vehicle including a control circuit for sensing rotation of said driven wheels and means of preventing the application of electrical power to said motor to reverse said motor until said wheels have slowed to a predetermined rotational velocity, said control circuit including a first control circuit for applying voltage to said motor causing said armature to rotate in a first direction;

• and a second control circuit for applying voltage to said motor causing said armature to rotate in a second direction, said second direction being opposite to said first direction;
• means for detecting said generated voltage;
• said preventing means comprising a first normally closed relay contact in series with said first circuit, and a second normally closed relay contact in series with said second circuit;
• a first holding circuit means controlling said first relay contact, a second holding circuit means controlling said second relay contact;
• said preventing means being responsive to said detecting means for preventing completion of said first circuit when said armature is rotating in said second direction and for preventing completion of said second circuit when said armature is rotating in said first direction;
• said first holding circuit means being responsive to said detecting means for holding said first relay contact in its open-circuit state until said armature has slowed to said predetermined speed when said armature is coasting in said first direction;
• said second holding circuit means being responsive to said detecting means for holding said second relay contact in its open-circuit state until said armature has slowed to said predetermined speed when said armature is coasting in said second direction;
• and wherein said second holding circuit means includes a first relay coil for controlling said second relay contact;
• a third relay contact responsive to said first relay coil and being in series with said first relay coil;
• a fourth relay contact in parallel with said third relay contact;
• a second relay coil in series with said first control circuit for controlling said fourth relay contact;
• and wherein said first holding circuit means includes a third relay coil for controlling said first relay contact;
• a fifth relay contact responsive to said third relay coil in series with said third relay coil;
• a sixth relay contact in parallel with fifth relay contact;
• and a fourth relay coil in series with said second control circuit for controlling said sixth relay contact.