The flipper of a spreader is the part of a spreader that bears the brunt of impact loading on a shipping container during transport. The flipper must be flexible enough to withstand impacts with the quay or within cell guides of a ship without damage while also maintaining rigidity for normal load application.

The present invention provides a spreader flipper with an ability to back drive if a preset torque about the flipper hinge is exceeded corresponding to an unusually high impact force. This is accomplished by the use of a motor and gear box with a spacing assembly between these two components which transmits torque to a hinge mounting of the flipper.

In one embodiment the motor and gear box may be replaced by a servo-motor which has an ability to provide feedback to the driver to assist in the maintenance of resistance against torque applied by the spacing assembly. This may be advantageous in that a back drive torque applied by the motor may be maintained even when the motor is stationary to reduce or prevent the risk of damage to the flipper.

Another alternative to the motor and gear box is a gear box that can be arranged in a cross helical or bevel arrangement in lieu of a direct worm drive. This permits a much higher back drive torque to be transmitted to the motor via the gear box than would otherwise be possible with a worm drive gear box engaged directly with a flipper.