Outdoor environments are harsh. In order to keep your switches operating ad optimal conditions you will need to regularly clean and lubricate the point area and the gliders, as well as the hinges.
Ball bearing wheels should be regularly lubricated with Teflon spray to maintain optimal smoothness of operation. Non ball bearing wheels benefit from lubricating the axle journals.
This Teflon spray is highly preferred to grease or oil, because it doesn't attract dirt.