Improvements in earth-working and like equipment

摘要

977, 601. Automatic control of slip. HONEYWELL Inc. Dec. 30,1960 [Dec. 30, 1959], No. 44779/60. Heading G3R. The load on a powered vehicle is varied in dependence on the slip with respect to the ground subject to a limitation that the load cannot be increased to such an extent that the engine speed falls below a selected minimum. As shown, the slip of a tracked vehicle is determined by comparing the output of a velocity generator 34, driven by a track-driving sprocket 31, with the output of a velocity generator 74 driven at the ground-speed of the vehicle by an endless chain 51. The desired slip is set by a potentiometer 38 and the difference voltage is applied through a preamplifier 102, and time delay network 115,118 to an amplifier 120, the output of which controls an electro-hydraulic valve 146 connected to control the operation of an hydraulic actuator 141 positioning a cutting edge 21 of a scraper so as to maintain the slip constant by varying the load on the vehicle. The endless chain 51 is maintained free from slip by sensing the position of the down-going portion of the chain by a feeler 54, which controls a chain-driving motor 71 through a closed loop system 200. The engine speed, which is stated to be a function of engine-power, is sensed by a velocity generator 82, the output of which is compared with a reference voltage set by a potentiometer 91, and the difference signal is applied through a pre-amplifier 110 to the amplifier 120 to position the scraper blade 21 so as to maintain the load on the vehicle engine constant. The relative effectiveness of the slip and speed signals is determined by the bias sources 113,105 of the preamplifier 110,102 respectively. In examples, the biases are adjusted so that slip and power arc controlled equally or the bias on preamplifier 110 is adjusted so that above a predetermined engine-speed the amplifier is biased to cut-off, and the bias on amplifier 102 is adjusted so that slip both above and below a predetermined valve affects the amplifier 120. Positional feedback is applied to the amplifier 120 through a potentiometer 129.