Re: Trico Vacuum Wiper Motor question

Posted by HH56 On 2021/3/4 21:04:38

It does look like the motors are reversed side to side but if the hose connection is fixed and that motor is constructed like later motors I can't think of anything you could have done internally to change the way the motor works.

Typically the way the later wipers work is when the wiper is turned on a slide valve moves so vacuum is connected to a passage which goes to the middle port in the shuttle valve mechanism in the center of the motor. On variable speed motors the working passage under the supply valve is in the form of a tapered slit so the more the valve moves, a wider area of the slit is uncovered to allow more vacuum being admitted so the faster the motor goes. As the paddle moves side to side, an overcenter spring mechanism flips the shuttle valve back and forth to connect the center source passage to passages going to each side of the paddle. The spring mechanism flips the shuttle valve a few degrees before the end of the sweep so it can reverse the center connection and connect to the other side passage to pull the paddle in the opposite direction.

When turning the motor off the slide valve is moved to a position where vacuum is cut off to the shuttle valve or working port but is then connected to another passage in the lid which goes to the designated park side of the motor. Vacuum will pull the paddle all the way to that side usually past the point where the shuttle valve flips. There is probably a small seal on the side of the paddle that will touch the park passage outlet in the lid so vacuum will hold the paddle solidly against the park passage to lock it in place and prevent vacuum leaking into the regular running passage that is going to the shuttle valve.