THREE-POSITION SHIFT ACTUATOR

摘要

A three-position actuator assembly for selectively shifting a three-speed splitt er type auxiliary transmission section (14) is provided. The actuator assembly incl udes a piston portion (160) for axially moving a selected one of two shift forks (142/1 48) and a control circuit (162) comprising three three-way, two-position solenoid controlled valves (202/204/206) and two three-way shuttle valves (214/216). Only one solenoid is energized for each selectable actuator position and a failure of the pneumatic (200) or electrical power sources to the control circuit will not cause the actu ator to shift out of an engaged ratio.