Vehicle speed responsive brake and decelerator controls

Claim 1

An automatic decelerator device for use in track-type vehicles such as a bulldozer or the like, characterized by the combination of: (a) a vehicle speed change lever means having a plurality of speed stages for forward and backward drives, said speed change lever means including a gear shift lever, wherein a change of the vehicle speed and/or the drive direction is effected by said gear shifting lever; (b) a plurality of solenoid operated valves provided in a transmission gear and selectively used for changing over the vehicle speed and/or the drive direction; (c) a first controller with a servo-motor adapted to actuate the braking action of a brake means; (d) a second controller with a servo-motor adapted to actuate a decelerator; (e) a comparator adapted to compare an actual vehicle speed, which is detected by means of a revolution sensor provided near an output shaft of the transmission gear, with a preset vehicle speed previously supplied into the comparator so as to detect whether the actual vehicle speed thus detected is higher or lower than the preset one, and then generate a signal corresponding to the result of the detection; and (f) a solenoid operated valve control circuit coupled to said vehicle speed change lever means and said comparator and arranged to control said first and second controllers and said solenoid operated valves in response to the state of said speed change lever means and the actual vehicle speed.