Importance

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Abstract

A tractor locking differential (12, 18) is controlled by a solenoid operated hydraulic valve (34). The solenoid valve is in turn controlled by a logic circuit (36) which is responsive to signals received from a differential lock floor switch (32), application of brake lights (26) through the closing of a contact (28 or 30), and also from powering up the tractor. When the ignition (20) is turned on a flip-flop (50) within the circuit (36) will be cleared by action of a power up to clear circuit (58, 60, 64, 66) to dispose valve (34) in its unlocked position. After power up the operator can selectively lock or unlock the differential by application of momentary contact switch (32) which causes flip-flop (50) to toggle. When a brake light switch (28 or 30) is closed the flip-flop (50) will be cleared causing valve (34) to be disposed in its unlocked position.

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First Claim