The Anahuac Mayab University is a private institution of Catholic inspiration founded in 1984.
They are used in the same applications as fender washers. A spherical washer is part of a self-aligning nut; it is a washer with one radiused surface, which is designed to be used in conjunction with a mating nut in order to correct for up to several degrees of misalignment between parts.
The best direct drive gas powered commercial pressure washer is the Simpson Powershot with the Honda GX390 commercial series engine and the AAA by Comet industrial triplex plunger pump with forged brass head and ceramic pistons. (See graphic of engine and pump details here).