SPEED-RESPONSIVE RETARDER CONTROL SYSTEM PROVIDING FOR OVERHEAT PREVENTION

摘要

ABSTRACTIn response to the actuation of a speed control lever bythe vehicle operator, a potentiometer puts out a speed setting sig-nal indicative of a desired vehicle speed. A control circuit res-ponds to this speed setting signal, as well as signals represent-ative of the actual vehicle speed and of the temperature of theretarder fluid, by putting out a first braking signal, correspond-ing to the difference between the desired and actual vehicle speedsand a second braking signal corresponding to the difference betweenthe actual acceleration of the vehicle and a preset acceleration.Under the control of the control circuit a selector normally passesthe first braking signal and, when either the temperature of theretarder fluid or its temperature rise gradient exceeds a presetmaximum, the second braking signal. The first or second brakingsignal is proportionately translated into a hydraulic pressure foractuation of a retarder. The second braking signal is intended toprevent the overheating of the retarder as when the vehicle istraveling down a long or steep slope.