Re: Stewart's 1955 Packard 400
Posted by HH56 On 2024/3/15 11:54:13
The vacuum lines to the knob assy is for the feature that is only on 55-6 models and is for the lever that changes the sweep arc. Some Packard advertising called it a super fast sweep for use in heavy conditions but what it does is cut the overall sweep distance across the windshield by about a third so in effect the blades do not have as far to go before reversing so they sweep faster.
They used vacuum instead of a cable for that control so moving the lever on the switch assy connects ports in the switch so vacuum is supplied or cut off to the port on the plate in front of the motor. Behind that plate is a small piston like assy which changes a piece in the mechanism that moves the click valve which controls when the blades reverse. When piece changes valve uses different ports so the motor paddle does not travel as far.
Just FYI, there is a service article on checking the hose positions at the switch because if reversed, one of the switch ports being open to air will cause a vacuum leak and faint hissing noise when lever is in the normal operating position..
Attach file:
sweep.jpg (114.35 KB)
They used vacuum instead of a cable for that control so moving the lever on the switch assy connects ports in the switch so vacuum is supplied or cut off to the port on the plate in front of the motor. Behind that plate is a small piston like assy which changes a piece in the mechanism that moves the click valve which controls when the blades reverse. When piece changes valve uses different ports so the motor paddle does not travel as far.
Just FYI, there is a service article on checking the hose positions at the switch because if reversed, one of the switch ports being open to air will cause a vacuum leak and faint hissing noise when lever is in the normal operating position..
Attach file:
sweep.jpg (114.35 KB)This Post was from: https://packardinfo.com/xoops/html/modules/newbb/viewtopic.php?post_id=268818