Gearbox synchronizers. Features

Synchronizers for mechanical gearboxes are the subject of renewed interest, particularly with robotized gearboxes. The relative simplicity of mechanical gearboxes contrasts with the complexity of automatic gearboxes, and costs are naturally in proportion. What's more, mechanical gearbox technologies and production methods have long since stabilized, and innovations in steering and control have opened up new development prospects.

Mechanical gearboxes are fairly simple mechanical systems. The interactions between the basic elements (housings, bearings, gears) are generally well mastered, both statically and dynamically, while gear synchronizers remain specialized elements due to the diversity of functions to be performed and conditions imposed. Often, the complexity of such elements impresses the designer, who either extrapolates what is known in the hope of staying within reasonable limits, or relies on super specialists in the hope of getting the problem right.

Synchronizers are linking elements:

• made up of interlocking parts with complicated geometries (cones, splines, claws, etc.) and diverse materials (steels, alloys, coatings, oil, etc.);

• subjected to highly variable operating conditions over very short times (less than a second);

• must have reproducible, long-term operating characteristics (gearbox life).

Synchronizers are therefore sensitive elements that require :

• a detailed description of the components for the different scales of observation of the phenomena;

• clear definition of operating phases and associated mechanical models;

• results for the design and control of the behavior of the synchronizer and gearbox assembly.

The approach proposed in this series of articles aims, in the current state of knowledge :

• isolate the synchronizer element and define a working context ;

• analyze each elementary behavior and present an overall behavior model ;

• present results and study the influence of parameters .

The aim of all this is to provide the designer with useful reference points and calculation methods, either in the pre-sizing phase, or in the optimization and fine-tuning phase with synchronizer suppliers.