Were the GE Mobile Maids this bad?
While "Mobile Maid" was GE's term for a portable dishwasher, the models most of us collect are the models with the stainless steel "bow tie" impeller. Normally, the newer machines that used a pump and wash arm were better at cleaning and offered more flexible loading than the older impeller machines, but GE is an exception. The bow tie impeller GE dishwashers offered much better cleaning and food disposal than GE's Bakelite impeller dishwashers. We have figured that the stainless steel impeller offered a sharper leading edge to cut into the water and the wider design of the blade threw water better than the more cone with fins Bakelite design. Also very important, the stainless steel did not become dulled or chipped along the leading edge as it aged like the Bakelite was wont to do. Another thing that improved cleaning with these machines was the reversing pump. The earlier GE's ran the timer off the dishwasher's motor so the motor could not stop during drain. The timer just adtivated the drain pump motor, but this did not give the soil time to settle out of the water before draining, nor did the drain pump eliminate food particles by grinding them up as they were pumped out. The stainless impeller machines came to a stop before reversing. They used the same continuously advancing timer motor technology as GE washing machines which means that there had to be greater distance between the contacts to prevent arcing between them as the timer slowly revolved which meant longer pauses between having the dishwasher motor turn in one direction to throw water and then reverse to drain it. So the heavier soil got to settle in the sump before the pump out. When these machines drained, they pumped out completely and, during the last few seconds of the drain, the fill valve opened to flush the pump before the next fill.
The GEs like in your picture did not pump out completely each time they drained so heavier soil was retained in the water that sat in the pump and they had no filter to prevent particles from being recirculated. GE used a relatively large pump housing with a much smaller diameter turbine-type impeller in it. It could develop good pressure when the pump chamber was full, but as soon as the drain valve opened and water volume dropped, the pump could not empty itself. Sometime in the 80s or 90s, some of GE's TOL models had an auxillary drain pump to suck out the water in the bottom of the wash pump chamber. It was activated during a couple of the drain periods, one of which was after the main wash. It was a help, but long overdue.
It is because of these factors that what should have been an advance in dishwashing technology with the move from impeller to wash arm was, for GE, a step back.
