Abstract: A drop center wheel for use with tubeless tires having a pair of spaced, circumferential, radially outwarding extending bead retention flanges (16) on opposite ends of respective circumferential bead seat surfaces (14). An intermediate, circumferential, drop center (10) is disposed between and interconnects bead seat surfaces and has a lesser diameter than the least diameter of the bead seat surfaces. At least one blocking member (22) is mounted in the drop center for movement between a first position well within the drop center so that its radially outermost point (24) is located a radial distance from the axis of the wheel less than one-half of the least diameter of bead seat surfaces and a second position extending from the drop center such that the radially outermost point is located a radial distance from the axis of the wheel greater than one-half of the least diameter of the bead seat surfaces.

Abstract: PCT No. PCT/US79/00664 Sec. 371 Date Aug. 30, 1979 Sec. 102(e) Date Aug. 30, 1979 PCT Filed Aug. 30, 1979 PCT Pub. No. WO81/00600 PCT Pub. Date Mar. 5, 1981A lock valve (10) for use in a hydraulic system (90) for positioning the work implement of an earth working machine which includes first and second check valves (28, 30) and a piston section (60, 70, 62, 72) for each operable by pilot fluid. In a first mode, the piston sections (60, 70, 62, 72) permit seating of both check valves, while in a second mode, the piston sections interlock so that only one check valve can seat. The lock valve (10) operates in a hydraulic system (90) to lock a work implement, such as a blade for a motor grader, in a fixed position during a first operating mode, while providing a connection from one end of an implement actuator to vent during a second operating mode to insure that a shock absorbing means for the implement hydraulic system maintains a full shock absorbing capacity.

Abstract: Multiple embodiments of a hydraulic control circuit for a double-acting hydraulic motor to provide fluid at a relatively high pressure for operating the motor in a selected direction and otherwise providing operating fluid to the motor at a relatively low pressure, the control circuit including a dual pressure relief valve which is operatively responsive to the motor or an implement positioned by the motor to provide the two operating pressures. An additional dual pressure relief valve regulates the flow of exhaust fluid from one side of the motor to allow controlled response of the motor to external forces. The hydraulic control circuit of the present invention is preferably contemplated for operating a push-pull coupling to permit selective tandem operation of two vehicles.