HRL, I have three trucks with crank open windshields, '37 & '42 chevrolets and my '47 Diamond T. The Diamond T has a split windshield with two separate cranks. I call that "zonal climate control".
Since my trucks are stock, there is no better feeling than driving down the highway (at 45 mph) with the windshield cranked open on a warm summer day. The design does not pull in engine heat, rather fresh air over the top of the hood.
Regarding rain, I live in Arizona, so that is not much of a problem. I am sure rain is the chief reason designers abandoned the concept by 1950. There is an interesting difference between the '37 and '42 and that is the presence of corner drains along the window bottom of the '42. These drains connect with rubber hoses that go out the bottom of the truck behind the kick panels. Kind of a hokey arrangement.
Design is often an evolution and the drivers of these trucks cut their teeth on trucks with open cabs that might even have a roof if you were lucky. Crank open windshields probably seemed like quite an advancement. Today, I enjoy the "charm" of designs.
Kent
