The objective of the invention is to provide a hydraulic servo-mechanism for an automatic transmission, which acts immediately upon command from the transmission control unit (if computerized) to the valve body to make shifting decisions.
Another duty of the present servo’s such as in the T-700R4 and 4L60-E Chevrolet and General motors vehicles is to reduce drag on the drum, for improving lifespan of a transmission by setting the operational position of the hydraulic servo to the factory or upgrade kit specifications.
Still another object of the servo system is to reduce shift shocks of the band brake while achieving the specified individual duties. The accumulator softens the shift. It is like a shock absorber to provide a smooth seamless shift.
The jobs of the servo assembly/s become apparent from a review of Part 1 and Part 2 (below) in this series on servo assembly’s. Servo assemblies require a thorough freshen up on all transmissions.
The band is restrained at one end by an anchor pin and expanded by its own springiness when the rod is in the retracted position. The case of the automatic transmission has a machined support surface inside for supporting the outer circumference of the band over a short range thereby to restrict the expansion of the band. The support surface supports the band in the expanded state permanently.
The hydraulic servo has an apply oil chamber to be supplied with the transmission oil pressure created by the front transmission pump,
That’s it. An automatic transmission servo assembly described in full. Another part of the puzzle on how an automatic transmission works. Enjoy more educational automotive transmission articles on our GotTransmissions.com Blog.
