Glycerin. Glycerin is an ingredient that can be found in many beauty products because of its moisture locking properties. It is a form of sugar alcohol that is available naturally in vegetable oils and can also be the byproduct of soap making.
Definition of wheel and axle : a mechanical device consisting of a grooved wheel turned by a cord or chain with a rigidly attached axle (as for winding up a weight) together with the supporting standards
A straight axle is a single rigid shaft connecting a wheel on the left side of the vehicle to a wheel on the right side. The axis of rotation fixed by the axle is common to both wheels. Such a design can keep the wheel positions steady under heavy stress, and can therefore support heavy loads.