Defecting saw

Claim 2

A saw comprising: a carriage and controllable means for moving said carriage between a first retracted position and a second extended position; a sawing element mounted on said carriage and means for actuating said sawing element; a pair of spaced operator actuated push button switches for cycling said sawing element and carriage between said first and second positions; a control circuit including a timing circuit coupled to said pair of push button switches, said control circuit coupled to said controllable carriage moving means and responsive to the actuation of said push button switches for actuating said controllable carriage moving means only when said push button switches are simultaneously actuated and for returning said carriage to its first position whenever either one of said push button switches are released; and safety circuit means coupled to said means for actuating said sawing element such that said sawing element can be actuated only when said carriage is in said first position.

Claim 3

A saw comprising: a carriage and controllable means for moving said carriage between first and second positions; a sawing element mounted on said carriage; a pair of spaced operator actuated push button switches for cycling said sawing element and carriage between said first and second positions; and a control circuit including a timing circuit coupled to said pair of push button switches, said control circuit coupled to said controllable carriage moving means and responsive to the actuation of said push button switches for actuating said controllable carriage moving means only when said push button switches are simultaneously actuated, wherein said timing circuit comprises a pair of one-shot multivibrator circuits each having a control input terminal and an output terminal, each of said control input terminals coupled to a different one of said push button switches for providing at said output terminals an output pulse of predetermined duration in response to the actuation of said push button switches, and gate circuit means coupled to said output terminals of said one-shot multivibrators to provide a control output signal for actuation of said controllable carriage moving means only upon the coincident application of said output pulses from said one-shot multivibrators to said gate circuit means.

Claim 4

A saw comprising: a carriage and controllable means for moving said carriage between first and second positions; a sawing element mounted on said carriage; a pair of spaced operator actuated push button switches for cycling said sawing element and carriage between said first and second positions; and a control circuit including a timing circuit coupled to said pair of push button switches, said control circuit coupled to said controllable carriage moving means and responsive to the actuation of said push button switches for actuating said controllable carriage moving means only when said push button switches are simultaneously actuated, wherein said timing circuit comprises a pair of one-shot multivibrator circuits each having a control input terminal and an output terminal, each of said control input terminals coupled to a different one of said push button switches for providing at said output terminals an output pulse of predetermined duration in response to the actuation of said push button switches, and gate circuit means coupled to said output terminals of said one-shot multivibrators to provide a control output signal for actuation of said controllable carriage moving means only upon the coincident application of said output pulses from said one-shot multivibrators to said gate circuit means.

Claim 5

The saw as defined in claim 2 wherein said controllable means for moving said carriage includes a first solenoid for actuating said carriage in a first direction and a second solenoid for actuating said carriage in an opposite direction and first and second latching circuit means coupled from said gate circuit means to said first and second solenoids respectively for the selective actuation of said solenoids to cycle said carriage between said first and second positions.

Claim 6

The saw as defined in claim 3 wherein said gate circuit means includes a four input NAND gate having a pair of input terminals coupled to said push button switches and a pair of input terminals coupled to said output terminals of said one-shot multivibrators for developing an output signal applied to said first latching circuit means to actuate said first solenoid in response to predetermined input signals on all input terminals of said four input NAND gate.

Claim 7

The saw as defined in claim 4 wherein said gate circuit means further includes a two input NAND gate having a pair of input terminals coupled to said push button switches and an output terminal coupled to said first and second latching circuit means for actuating said second solenoid and deactuating said first solenoid in the event at least one of said push button switches is released by the operator.

Claim 8

The saw as defined in claim 5 and further including a first limit switch actuated when said carriage is in said first position and wherein said one-shot multivibrators include an enabling input coupled to said first limit switch and responsive to the actuation of said first limit switch for enabling the operation of said one-shot multivibrators only when said carriage is in said first position.

Claim 9

The saw as defined in claim 6 and further including a second limit switch actuated when said carriage is in said second position and coupled to said second latching circuit means for actuating said second solenoid when said carriage is in said second position.

Claim 10

For use in a machine employing a pair of spaced operator actuated push button switches to initiate a cycle of operation of the machine, an improved control circuit comprising: a timing circuit having input terminals for coupling to the operator actuated push button switches and responsive to the actuation thereof to provide a control signal at an output terminal thereof only when the push button switches are both actuated within a predetermined time period; logic circuit means for coupling to the push button switches and to said output terminal of said timing circuit for providing machine command signals at an output thereof for initiating a cycle of operation of the machine in response to the receipt of said control signal and signals from said push button switches indicating that they have been actuated for interrupting said command signal in the event either one of the push button switches is released before a cycle of machine operation is completed.

Claim 11

For use in a machine employing a pair of spaced operator actuated push button switches to initiate a cycle of operation of the machine, an improved control circuit comprising: a timing circuit having input terminals for coupling to the operator actuated push button switches and responsive to the actuation thereof to provide a control signal at an output terminal thereof only when the push button switches are both actuated within a predetermined time period; logic circuit means for coupling to the push button switches and to said output terminal of said timing circuit for providing machine command signals at an output thereof for initiating a cycle of operation of the machine in response to the receipt of said control signal and signals from said push button switches indicating that they have been actuated for interrupting said command signal in the event either one of the push button switches is released before a cycle of machine operation is completed.

Claim 12

For use in a machine employing a pair of spaced operator actuated push button switches to initiate a cycle of operation of the machine, an improved control circuit comprising: a timing circuit comprising a pair of one-shot multivibrator circuits each having a control input terminal and an output terminal, each of said control input terminals coupled to a different one of said push button switches for providing at said output terminal an output pulse of predetermined duration in response to the actuation of said push button switches within a predetermined time period; logic circuit means for coupling to the push button switches and to said output terminal of said timing circuit for providing machine command signals at an output thereof for initiating a cycle of operation of the machine in response to the receipt of said control signal and for interrupting said command signal in the event at least one of the push button switches is released before a cycle of machine operation is completed.

Claim 13

For use in a machine employing a pair of spaced operator actuated push button switches to initiate a cycle of operation of the machine, an improved control circuit comprising: a timing circuit comprising a pair of one-shot multivibrator circuits each having a control input terminal and an output terminal, each of said control input terminals coupled to a different one of said push button switches for providing at said output terminal an output pulse of predetermined duration in response to the actuation of said push button switches within a predetermined time period; logic circuit means for coupling to the push button switches and to said output terminal of said timing circuit for providing machine command signals at an output thereof for initiating a cycle of operation of the machine in response to the receipt of said control signal and for interrupting said command signal in the event at least one of the push button switches is released before a cycle of machine operation is completed.

Claim 14

The circuit as defined in claim 9 wherein said logic circuit means comprises gate circuit means coupled to said output terminals of said one-shot multivibrators to provide an output signal only upon the coincident application of said output pulses from said one-shot multivibrators to said gate circuit means.

Claim 15

The circuit as defined in claim 10 and further including a first solenoid for actuating a machine element in a first direction and a second solenoid for actuating the machine element in an opposite direction and first and second latching circuit means coupled from said gate circuit means to said first and second solenoids respectively for the selective actuation of said solenoids to cycle the machine element between the first and second positions.

Claim 16

The circuit as defined in claim 11 wherein said gate circuit means includes a four input NAND gate having a pair of input terminals coupled to the push button switches and a pair of input terminals coupled to said output terminals of said one-shot multivibrators for developing an output signal applied to said first latching circuit means to actuate said first solenoid in response to predetermined input signals on all input terminals of said four input NAND gate.

Claim 17

The circuit as defined in claim 12 wherein said gate circuit means further includes a two input NAND gate having a pair of input terminals coupled to the push button switches and an output terminal coupled to said first and second latching circuit means for actuating said second solenoid and deactuating said first solenoid in the event at least one of the push button switches is released by a machine operator.