Electric motor control circuit and switching means

Claim 2

An electrical motor control circuit comprising: a source of power of a fixed polarity; first and second sets of contactors; a motor having an armature and field coils, said first and second sets of contactors applying a reversible polarity voltage across said field coils to control the direction for current flow and thus the polarity at said armature; first and second actuating means selectively movable between first and second positions to respectively actuate said first and second sets of contactors to cause said armature to rotate in a selected direction when in said first position, and brake rotation of said armature when in said second position; a switching means operable in response to the position of said actuating means to move between first and second positions, one of said actuating means positioning said switching means to said first switching means position when said one actuating means is moved to its first position, said switching means remaining in its first position to electrically ground said armature and field coils when said one actuating means is moved to its second position; the other of said actuating means positioning said switching means to said second switching means position when said other actuating means is moved to its first position, said switching means remaining in its second position to electrically ground said armature and field coils when said other actuating means is moved to its second position.

Claim 3

The electrical motor control circuit as defined in claim 1 wherein said armature and field coils are grounded through a resistor.

Claim 4

The electrical motor control circuit as defined in claim 2 wherein said resistor is a variable resistor.

Claim 5

An electrical motor control circuit comprising: a source of electrical power; an electrical motor including an armature and field coils having a pair of input terminals; means for selectively connecting said terminals to said source of electrical power for selectively rotating said armature in opposite directions and for disconnecting said source from said terminals to stop said rotation; said last mentioned means comprising: first and second switch means each including first and second normally closed contacts, first and second normally opened contacts, and a third contact electrically connected to said first normally opened contact; said second normally opened contact of said first switch means and said first normally opened contact of said second switch means being respectively connected to said source of electrical power; said first normally opened contact of said first switch means and said second normally opened contact of said second switch means being respectively connected to said pair of input terminals; said first and second normally closed contacts of said first switch means being respectively grounded and connected to said first normally closed contact of said second switch means; a third switch means having a contact member movable between first and second positions respectively engaging said third contacts of said first and second switch means; first actuating means being operable between first and second positions to respectively open and close said first and second normally closed contacts of said first switch means and close and open said first and second normally opened contacts of said first switch means while moving said third switch means into its first position when said first actuating means is in its first position, said third switch means remaining in its first position when said first actuating means is returned to its second position; and second actuating means being operable between first and second positions to respectively open and close said first and second normally closed contacts of said second switch means and close and open said first and second normally cloSed contacts of said second switch means, while moving said third switch contact to its second position when said second actuating means is in its first position, said movable contact member remaining in its second position when said second actuating means is returned to its second position.

Claim 6

An electrical motor control circuit comprising: a source of electrical power; an electrical motor including an armature and field coils having a pair of input terminals; means for selectively connecting said terminals to said source of electrical power for selectively rotating said armature in opposite directions and for disconnecting said source from said terminals to stop said rotation; said last mentioned means comprising: first and second switch means each including first and second normally closed contacts, first and second normally opened contacts, and a third contact electrically connected to said first normally opened contact; said second normally opened contact of said first switch means and said first normally opened contact of said second switch means being respectively connected to said source of electrical power; said first normally opened contact of said first switch means and said second normally opened contact of said second switch means being respectively connected to said pair of input terminals; said first and second normally closed contacts of said first switch means being respectively grounded and connected to said first normally closed contact of said second switch means; a third switch means having a contact member movable between first and second positions respectively engaging said third contacts of said first and second switch means; first actuating means being operable between first and second positions to respectively open and close said first and second normally closed contacts of said first switch means and close and open said first and second normally opened contacts of said first switch means while moving said third switch means into its first position when said first actuating means is in its first position, said third switch means remaining in its first position when said first actuating means is returned to its second position; and second actuating means being operable between first and second positions to respectively open and close said first and second normally closed contacts of said second switch means and close and open said first and second normally cloSed contacts of said second switch means, while moving said third switch contact to its second position when said second actuating means is in its first position, said movable contact member remaining in its second position when said second actuating means is returned to its second position.

Claim 7

The electrical motor control circuit as defined in claim 4 wherein said third switch means comprises: an electrically nonconducting mounting plate; first and second flexible members, the opposite ends of each of said flexible members being carried by said plate and having first and second movable contacts respectively carried on their free end; first and second fixed contacts carried on said plate, said flexible members being of sufficient resiliency that said first and second movable contacts are respectively normally biased into engagement with said first and second contacts; an arm member mounted at its midsection on said plate at a point spaced from said first and second flexible members, said arm member being rotatable between first and second positions respectively in response to said first and second actuating means and so arranged that when said arm member is rotated in one direction in response to one of said actuating means said arm member engages the underside of one of said flexible members to raise the movable contact carried thereby away from its associated fixed contact; said arm member engaging the underside of the other of said flexible members when rotated in an opposite direction to raise the movable contact carried thereby away from its associated fixed contact; means electrically connecting one of said movable contacts to one of said input terminals of said armature and for electrically connecting the other of said movable contacts to the other of said input terminals of said armature; and means for electrically connecting said fixed contacts to said second normally closed contact of said second switch means.

Claim 8

The electrical motor control circuit as defined in claim 5 wherein said armature is grounded through a resistor.

Claim 9

An electrical motor control circuit as defined in claim 6 wherein said resistor is a variable resistor.