Caterpillar Inc.

Stuart J Walker

David L Dickrell

Jeffrey F Birkel

David B Mason, Jr

Transmissions in which the mechanical gear shift arrangements are replaced by electro-hydraulic operated shift mechanisms that have to be able to be neutralised positively to ensure a proper operation. An arrangement and method are provided to determine the position of the shift rail so a shift can be made only if the conditions are right. To prevent engagement of two shift members at the same time and consequent damage in case of electronic failure, mechanical safety features such as detents are included.

Transmission and shift method

A shift control method for an automated manual transmission is provided. The method includes the step of modulating the force applied to a shift collar, via a shift rod and/or shift fork for example, during the engagement of the shift collar and a selected gear. The method modulates the initial engagement force applied to the shift collar when the rotational speed differential between the collar and gear is being adjusted, before increasing the force again following modulation. This modulation of the force decelerates the shift collar during the rotational speed adjustment and does not accelerate the shift collar to complete the engagement until after the modulation. In this way, a less abrupt engagement of the gear may be achieved. The control method may improve the driving characteristics of the vehicle employing the transmission and may also improve the power transmission efficiency.

Growing community of inventors

Shifnal, United Kingdom

Stuart J Walker