Totoya (SAS) system. Swing lock cylinder
The first actuator controls the swing lock cylinder helping to prevent truck overturn sideways. A counterbalanced forklift truck is based on a three point system consisting of the two front wheels and the middle of the rear axle shown above.
In order for the truck to remain stable the centre of gravity must stay inside the triangle shown here. The swing lock cylinder locks the rear axle in position preventing it from articulating as shown here.