CMP windshield throwout arm assemblies

[Grant Bowker]

Originally Posted by Lynn Eades

There are lots of variations in vacuum wipers, up into the later 50s (particularly British cars, often with a vacuum tank (with the hope that you might get at least one wipe as you climbed a hill) These were mostly mounted under the dash so had a separate control.
There were larger units (cylindrical bodies) in the M series trucks that were new (to the N.Z. Army) after the Vietnam war (70s) (e.g.M816- M818)
These were fitted in Wagner logstackers up to 2000. These big units, as I recall were pressure rather than vacuum. (still available?)

When younger, I owned a M135CDN 2-1/2 ton truck. Being gasoline powered, the truck would have been capable of generating vacuum to run wipers but the truck definitely used compressed air to run the wipers, taken from the system that provided air pressure for brake boost, trailer braking and also had an outlet under the dash for a hose to inflate tires. I presume other trucks of the same vintage may have used similar components. One advantage of using air pressure is that if there is a small leak, there's no chance of drawing water into the engine (recall that they made a big thing of the early M series being sealed to run under water).