Transmission control system with logic for preventing improper shifting after changing intention

摘要

In a transmission system, a solenoid controlled electro-hydraulically actuated creeper mechanism coupler (15) permits selection of very low speeds and provision is made to prevent creeper gear engagement/disengagement, unless controlled by the operator and then only if specified conditions exist. Current flow through the solenoid (83) which actuates the creeper mechanism (70) is monitored at all times to provide a controlled engagement/disengagement of the creeper mechanism (70) in the event the monitored conditions are not within prescribed limits. The current is monitored as the creeper solenoid (83) is energized, while it is energized and when it is not energized so that short or open circuit conditions may be detected before they can cause an unexpected engagement or disengagement of the creeper mechanism (70).