Four wheel tractor

Claim 1

A self leveling tractor comprising an elongated fixed main frame having a motor and cab mounted thereon, rear and front sub frames, said rear and front sub frame being positioned centrally and lengthwise below the rear and front portions respectively of the main frame, said sub frames each having opposing longitudinal side frame members parallel to the length of the main frame and front and rear lateral frame members perpendicular to the length of the main frame, with the longitudinal side frame members being of greater length than the front and rear lateral frame members, so that the length of the sub frames is parallel to the length of the main frame, projecting lug means on opposing side frame members of the rear sub frame projecting outwardly from beneath the main frame to fix a rear axle to the underside of the rear frame so that the rear sub frame rests generally on top of the rear axle, and spaced below the main frame when the rear sub frame is horizontal with the main frame, said front sub frame having means on the opposing side frame members to fix a front axle to the underside of the front sub frame so that the front sub frame rests generally on top of the front axle, said lateral front and rear members of said front and rear sub frame being pivotally mounted to the main frame, said pivotal mounting of said sub frames being each pivotally mounted on generally one common axis to one another, with the axis extending centrally and longitudinally along the length of the sub frames and main frame at a location spaced above the longitudinal center axis of the front and rear axles with the distance between the pivot points of the front and rear lateral members of the front and rear sub frames greater than the distance between the front and rear edge of their respective axles at the center of the axle, said rear sub frame being spaced above an input shaft to said rear axle, so that a drive shaft means may connect said motor to said rear axle that will pass beneath said rear sub frame member, said front sub frame member being spaced above an input shaft to said front axle so that a drive shaft means may connect said motor to said front axle that will pass beneath said front sub frame member, a fluid cylinder positioned above one of the side frame members on the rear sub frame with one end pivotally connected to the upper surface of said frame member and the other end extending upward and pivotally mounted to an opposing side portion of the main frame, motor and pump means to activate said cylinder, mercury activated leveling means to control the actuation of said valve and pump means to control the activation of said cylinder, with said cylinder when activated by said mercury activated leveling means pivoting said main frame relative to said rear sub frame to level the main frame to horizontal, when said rear sub frame has pivoted to one side or another due to being located on angular terrain.