Transmission shift control device system

摘要

An automatic multiratio drive transmission having an automatic shift control system with a speed and throttle position pressure controlled shift valve controlling shifts between the highest drive ratio and the next lower drive ratio. When the shift valve is in the lower drive ratio position, a normal speed pressure signal increasing with increasing speed acting on the shift valve overcomes an opposing bias force controlled by throttle pressure to upshift the shift valve to the higher drive ratio position at increasing upshift speeds for increased throttle positions and provides an upshift hysteresis force decreasing with increasing throttle positions to prevent shift cycling as the highest ratio is established in a short time period and after a longer time delay period reduces the normal speed related governor pressure in an amount equal to the upshift hysteresis force at full throttle so that the downshift speed is the same as the upshift speed at the full throttle position.