215,054. McDowall, A. Jan. 26,1923. Power cultivation; balance implements; travelling and propelling gear; side-stepping at headlands; balance weights.-An endless track or wheeled agricultural tractor comprises a frame 2 having at one side two supporting and driving wheels 4 which may be connected by an endless band 6, and a single supporting and driving wheel 29 at the other side which is driven at a variable speed to steer the tractor Ploughs or cultivating, grubbing, harrowing, and like implements may be attached to the tractor The electric or other motor 9 drives a change-speed gear 10 from which the steering and driving-wheel 29 is driven through variable expanding-pulley gear 19, 21, a clutch 19a, and gearing 23, 26. The endless track wheels 4 are driven through worm and spur gearing and chain gearing 17, being also connected together by chain gear 18. The expanding-pulley gear may be varied to steer the tractor either by hand or automatically by an arm 71 having discs 70 travelling in a previouslymade furrow. Ploughs may be attached at either end of the tractor by a spring-coupling 67 which yields when the plough encounters an obstruction and is arranged to stop or control the speed of the motor. Each end of a plough may be connected bv chains to the tractor so that it moves with the tractor when the latter is reversed. A movable counterweight 63 is provided to prevent rearing of the tractor, and the ploughs at front and rear are connected together for balancing by a chain 65 passing over pulleys on the top of the tractor. At the end of each furrow the tractor must be moved sideways; to effect this the driving wheels are de-clutched from the engine and a shaft 42 is driven. When this shaft is rotated a transverse roller 51 is lowered, thus raising the side wheel 29 from the ground, and pivoted legs 46 having feet 47 are lowered into contact with the ground, so that the tractor is raised and tilted by the feet and moves sidewise away therefrom. The distance through which the tractor moves can be regulated by adjusting the position of bars 49 to which the legs are pivoted. According to one Provisional Specification, eccentric drums or rollers may be used to traverse the tractor sidewise. A derrick may be provided on the tractor whereby any cultivating implement in use may be swung round from one end of the tractor to the other. When the motor is an electric one, current is supplied to it from a cable wound on a drum 34a which is driven through a clutch 33a automatically engaged and disengaged by axial movement of the drum according to whether the cable is to be wound in or allowed to pay out. An auxiliary cable carriage forming a connecting link between the power supply and the cable drum 34a on the tractor is described, but does not form part of the invention. This carriage 55, Fig. 5, carries a drum 39 for the main supply cable 38, slip rings on this drum being connected to a cable 34b passing over a guide 56 to the tractor drum 34a. The carriage is placed in the field so that the tractor passes it when half-way along a furrow. As the tractor passes the carriage an inclined surface 60a on the tractor strikes a wheel 57 on the carriage, thus pushing the carriage back and rotating the wheel to wind up the main supply cable on the drum 39. The wheel 57 can only rotate the drum 39 in one direction, so that the cable is not paid out when the tractor passes in the other direction. At the same time a striker on the tractor is operated by the wheel 57 and causes the tractor drum 34<a> to be moved axially so that it is still in line with the end of the guide 56, while the drum, which has been winding in the cable 34b, is now declutched so that it can pay out as the tractor moves away from the carriage.