Patent GB-1371128-A (GB)
Title: Electric drive riding or tractor mower
IPC: A01D69/02
Filed: 1972-08-30
Abstract: 1371128 Controlling vehicles DEERE & CO 30 Aug 1972 [31 Aug 1971] 40207/72 Heading B7H [Also in Divisions A1 and H2] An electrically powered tractor power unit 10, has a belly mounted cutting apparatus 82, a D.C. power pack 94, a D.C. traction motor 56 for driving a pair of rear ground wheels 14, two D.C. mower motors 92, 93 for driving cutter blades 88, 89 respectively and an electrical control circuit which includes a pair of manually operated switches for the motor 56 and the two mower motors 92, 93 respectively, and an overload protection arrangement for all the motors. The overload protection arrangement includes circuit breakers that cut out a respective motor if an excessive loading occurs and will maintain that motor in a deactivated condition until it is intentionally restarted by the operator. The tractor includes front steerable wheels 12, a steering column 28, brake and clutch foot pedals, a gear lever 50 and a panel 50 carrying the two switches which are actuated by a key 128 and lever 132 respectively. The traction motor 56 drives the rear wheels 14 via a rear transmission and drive axle 44 which has an input shaft driven from the motor 56 by a belt and pulley system 52, 53, 54. The axle 44 includes a gear system providing a neutral, three forward speed ranges and a reverse which are selected by the gear lever 50 via a linkage and a lever 48. The traction motor 56 is held in a support bracket which is mounted to swing fore and aft about a vertical pivot when the clutch pedal is depressed against a biasing spring to thereby relieve the tension in the belt 54'and effectively de-clutch the motor. An output shaft of the rear axle 44 has a pulley 74 which is' engaged by a brake band 76 on depressing the brake pedal 78. The cutting apparatus 82 is suspended by a linkage 83 and is raised and lowered by a lever 84 to adjust the cutting height. The electrical control circuit (see Fig. 3, not shown).-A master relay connects the power pack 94, comprising three lead acid accumulators to the traction motor 56 and a mower relay and the relay is closed by energizing circuits which include the key operated switch, a thermostat switch which opens if the temperature of the motor 56 exceeds a predetermined value and a switch which is closed when the clutch pedal is depressed to disengage the drivetransmission. The mower relay connects the two mower motors 92, 93, which are linked in parallel, to the power pack and has energizing circuits which includes the lever operated switch and two circuit breakers associated with a respective mower motor. The two switches both have three positions-"start", "run" and "off". To start the traction motor 56, the key operated switch is turned to "start" and the clutch pedal depressed -to close the associated switch, the master relay closes and the motor 56 is connected to the power pack. On releasing the key the switch is returned by a spring to a "run" position. The two mower motors 92, 93 can then be started by similarly operating the lever operated switch. If the circuit breaker for either of the mower motors operates, the motors are cut off and are rapidly stopped by a load circuit, connected to the mower relay, which dissipates any back e.m.f. generated by the motors through a resistance. If thermostat switch operates the traction and mower motors are all cut off and can only be restarted by going through another "start" routine. The power pack 94 can be recharged through a battery charger 98 from the mains.