How containers securing on the vessel ( Part 1 -Base lock)

Tutorial about base lock mostly used on container ships.
Bottom base locks are used on the bottom corners of containers sitting on hatch covers, pedestals and deck extensions. At sea, these twistlocks incur longitudinal forces caused by torsional deformations of the ship’s hull. These longitudinal forces have to be addressed by either incorporating sliding foundations or by using ISO standard twistlock foundations, which have an elongated ISO hole. When torsional deformation occurs the containers will slide on the pedestals, causing wear to the base of the twistlocks. When the forces and the torsional deformation are large the wear can be excessive. In worst case scenarios, the forces and wear can cause cracking and finally failure of the bottom base locks during a voyage.

[boensad]

I mean it seem no need big power to push or pull?