Date: 19 May 2003 03:59:10 GMT From: davehinznopsamcop.net Subject: Re: Washer Check Valves - give me some theory
Someone who looks an awful lot like Joe User <Joenopsam.nut> wrote: > My theory is it's over-engineered. Jees, just shoot the liquid with I > ask! (mine's clogged too, by the way) Well, they're there to also keep the liquid from draining all the way out of the hoses back to the tank, so without them there would be a long delay with nothing. The presence of a checkvalve in the nozzles goes back, by the way, at least to the 1960 Saab model 96; it was necessary in that car because the wiper fluid "pump" was the driver, pulling out on the knob, which filled a spring-loaded chamber with the fluid; the spring then pulled the plunger back in, spraying the windshield. An interesting mechanism couples that plunger's square shaft, over to an electrical switch for the wiper motor, so turning it controls the motor, pulling it out gives the washers fluid to spray. But, it wouldn't have filled up if it could pull air from the nozzles rather than fluid from the tank, so the check valves were put into the nozzles at that time. I'm sure the benefits of having them there (fast spray startup) were one of the reasons to keep the, long after the fancy new-fangled electric washer fluid pumps came in, around '65 I think. Dave "I've got several of 'em, new on the shelf, actually" Hinz
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