It is the system of agitation that best characterizes a washing machine.  Within this 
photo gallery I have shown the agitators of a few of my machines.  

The file name of these photos includes an abbreviated description of the type of 
agitation and the machine ID number of the washer.  I am still revising the names of 
these agitation systems and inventing new ones.  Sometimes the intention of the 
inventor is not evident.  For example, look at the "dollydragcone21".  What is the 
primary agitation scheme?  The agitator is comprised of a cone with "ears" to which 
the clothes could be attached to drag them through the water. 
It is one of the main sources of enjoyment in collecting washing machines to find a 
machine with a different agitation system from the ones you already have. There seem 
to be an endless number of agitation concepts that must have resulted from an equal 
number of sleepless nights.  Invention is a curious and marvelous attribute of human