[mawshj]

the theory is that the vanes act as a positive displacement pump at low speeds and flex more and more as speed increases there by regulating water pressure so to protect gaskets and hoses. also allows sand to flow thru . at w.o.t. the vanes do not touch the outer pump housing but act as a turbine pump. I do not know if it really works that way but that's what I was told by O M C man.