The ALSTOM SO system is a range of hydraulic actuators, which provide positive point blade movement proportional to their position in the turnout.

The system includes both back drives and swing nose frog drives (originally developed for the Italian market), to meet the requirement for various lengths of turnout, including high speed.

Each individual drive contains its own integral lock and electrical lock detection to provide confirmation that the correct turnout geometry has been safely established. These locks and electrical detectors are sealed within the body of the drive to avoid contamination. Once an actuator is locked the hydraulic drive pressure is reduced to ambient.

The system was specifically designed to provide zero maintenance for 15 years (or 500,000 operations).

To allow for machine tamping, the drives are mounted on bearer and all connections are clear of the tamping zone.

The actuators are protected from damage during inadvertent trailing by a mechanical fuse.

Speed of operation is governed by applied hydraulic pressure and flow.

The system is supplied as a complete kit for a specific turnout and comprises:-

• Actuators (complete with rail attachments)
• Hydraulic connections
• Electrical connections (to line side)
• Actuator protection covers
• Stretcher bar protection cover
• Hose protection covers
• Mounting hardware