Patent ID: 8910741

Claim:
A steering device for a tractor, comprising a steering cylinder receiving, by means of hydraulic pressure, a steering force generated when a driver manipulates a steering wheel and turning front wheels of the tractor, wherein the steering cylinder comprises a cylinder body and left and right cylinder rods provided to be extended from and retracted into the cylinder body to the left and the right, the steering cylinder being disposed at a position spaced apart from a front wheel axle housing by a predetermined distance and being parallel to the front wheel axle housing, ends of the left and right cylinder rods are respectively hinged to swing links to form a first four-bar link structure that is swung by extension and retraction of the steering cylinder, whereby the front wheels are steered, a support link is hinged at a first end thereof to the front wheel axle housing and hinged at a second end thereof to the cylinder body so that when the steering cylinder is operated, the steering cylinder is allowed to move forwards or rearwards within a predetermined range while being prevented from moving to the left or the right, and a device for sensing a steering angle of the steering cylinder, wherein when the device for sensing the steering angle senses that a steering angle of the steering cylinder exceeds a predetermined range, a four-wheel drive mode in which the front wheels and rear wheels are rotated at a same rpm is converted to a differential four-wheel drive mode in which a difference in rpm between the front wheels and the rear wheels is adjusted, wherein the device for sensing a steering angle of the steering cylinder comprises: a guide rail provided parallel to the steering cylinder and coupled at opposite ends thereof to the respective ends of the cylinder rods, with a sensing protrusion provided on the guide rail, so that when the cylinder rods move, the guide rail is moved, and the steering angle of the steering cylinder is sensed by the sensing protrusion.