A tractor has three pairs of ground wheels: a front steerable pair, a rear steerable pair and a central pair. The central pair of wheels each are fitted to the frame through a hydraulic piston assembly that can be controlled to raise those wheels above the ground or to lower the wheels to engage the ground. The central wheels can be the same as the other wheels or traction caged wheels of hollow beams wherein a hub is connected to outer fellies with spokes. Supports interconnect the fellies at the inner or outer sides. All of the wheels can be driven independently by an engine and the central wheels are each detachable from a driven axle. The hub of the central wheels includes an outer cylindrical sleeve to which an end plate and the spokes are affixed. Each wheel is mounted on a hydraulic motor which is mounted on the tractor's frame, the forward and rear motors being turnable with the wheels mounted thereon. A hydraulic jack connected to the motors of the central wheels is adapted to raise and lower same. Hydraulically actuated three-point lift devices are provided on the tractor frame to extend forward between the front two wheels and rearwardly between the two rear wheels. Front and rear power take-off shafts are also provided. Power is provided by an engine located between the axes of rotation of the front and central wheels to a hydraulic pump and thence separately to each of the hydraulic motors and the hydraulic actuated mechanisms.
RELATED APPLICATIONS
This application is a continuation of application Ser. No. 816,254 filed July 15, 1977 which is a division of application Ser. No. 588,156 filed June 19, 1975, now abandoned.
An agricultural tractor having six wheels which are each hydraulically drivable by individual hydraulic motors through hydraulic fluid supplied by respective hydraulic pumps. With each pump driving only one wheel, skidding of a wheel does not affect drive to other wheels. The pumps are all driven by a single engine. Selectively operable automatic control means control the speed of the wheels when, for example, the tractor is turning. Control means are also responsive to the drag resistance of an implement hitched to the tractor's lifting members and cause such lifting members to raise when the implement's resistance exceeds a predetermined limit. In addition, speed of the vehicle is automatically reduced by reason of such resistance and, further, the position of the implement relative to the ground may be adjusted to offset at the location of the implement upward and downward movement of tandem wheel pairs at the rear of the tractor. Such adjustment is effected by the lifting device and is delayed for a short period to allow movement of the vehicle.
A wheeled platform 100 is disclosed, which is characterized by high mobility and reliability, and which can be used in a wide range of applications including transport and robotic devices. The wheeled platform 100 has fore and aft body portions 130, 132, each body portion 130, 132 having first and second sides 106, 108. Overlapping wheels 112, 114, 116, 118 are rotatably attached to the first side 106 and overlapping wheels 120, 122, 124, 126 are rotatably attached to the second side 108. The fore body portion 130 can be connected to the aft body portion 132 via an articulation element 133.
