Automated Side Shaft Insertion Cell: Automated Joining of Drive Shafts on Drive Units

Anyone who has ever tried to fit a splined shaft into a spline hub by hand knows the problem: if the tooth positions don't line up, the tooth flanks hit each other instead of meshing. What can be solved manually with a small twist of the wrist becomes a demanding task in automated series production. The relative angular position between the external and internal spline is random when the components are brought together — if tooth meets tooth instead of tooth meets gap, engagement is blocked. Until now, this has either been reworked manually or bridged with pneumatic systems that operate with fixed end positions and undefined forces — with the well-known consequences: wear, damaged components, irregular downtime.

AuE Kassel, a company of the STRAMAGROUP and long-standing specialist in axle assembly lines, has developed an automated cell with a patented process strategy for exactly this process step, fully automating and standardizing the engagement of side shafts on rear axle gearboxes and e-drives — with a low-sensor process concept.

The process strategy continuously evaluates force and travel data, reliably detecting whether the splines have already engaged successfully or whether only a tooth-on-tooth situation is present. If a tooth-on-tooth situation is detected, the system first withdraws the side shaft in a controlled manner. A defined servo-electric angular correction then follows, before the next joining attempt starts automatically. This patented, pulsing search process repeats itself independently until the splines are securely engaged. In practice, engagement is usually achieved reliably within just a few cycles.

A floating-mounted guide unit compensates for positional deviations between the side shaft and the drive, supporting the self-alignment of the components during engagement. This reduces lateral forces and increases process reliability. What was once a random engagement attempt becomes a reproducible, fully automated assembly process.

The actual joining force is regulated through a servo-electric force-travel process rather than applied pneumatically. A pull-out test can optionally be integrated directly afterwards to verify the finished connection immediately.

The automated cell is suitable for joining side shafts on rear axle gearboxes, e-drives, hybrid drives, differential assemblies, and other drive systems with internal splines. With a footprint of around 3 x 3 meters, it can be integrated into existing assembly lines for axles and drive units without major effort — including for the simultaneous joining of side shafts on both sides.

Instead of forcing the joining process with higher forces, AuE Kassel relies on intelligent process control: The system automatically detects the condition of the gear teeth and makes adjustments until the mesh is secure. This transforms what appears to be a simple but error-prone assembly task into a robust, repeatable process for modern drive systems.