GATOR - a compliant seal free hydraulic PTO

Overview

The project aimed to develop and test a novel, innovative hydraulic PTO concept consisting of a flexible compliant polymer spring tube.

This polymer spring (or Gator) can be designed with a wide range of non-linear response curves allowing tailoring of the stress strain response. The seawater compatible Gator acts as a pump compressing internal fluid (such as sea-water) and driving a hydraulic PTO system. As it does not require any seals, is designed for tens of millions of compression cycles, can be fabricated at reasonable cost at all scales, is seawater compatible, and can be implemented in a system with very low maintenance requirements, it offers a potentially appealing LCOE for renewable energy PTO requirements.

The Gator PTO spring pump itself is manufactured from engineered polymer materials and needs no seals so therefore offers a truly contamination-tolerant pumping device. Using a thermoplastic rather than a rubber polymer allows for much stiffer responses to be achieved and higher water pressures to be pumped. The non linear response of the spring allows for the spring stiffness to be much lower than the pumping pressure under normal operating conditions but to dominate the forces in survival conditions, delivering inbuilt survivability to the PTO.