D4 7U fan--pusher vs. puller

Pusher fans on6U & 7U,s not common ,I have 4,D-6u&7u ,s ,all have puller fans
Actually pusher fans are more efficent to draw heat away from the engine.
I am wondewring if you have a high ser# abouve 29000 where Cat added the option ?

Huh?

Efficient heat transfer relies on cooler air moving past a heated object (radiator). How does heated air from a hot engine going through a radiator promote better cooling? I'm not being critical, just want to know.

Which is best, drawing cool air over the engine to go through the radiator, or pushing already warm air back over the engine to waft back over the operator? I'm told that pusher fans were introduced to stop drawing dust and dirt from the blade back into the radiator, but I reckon it was mainly to stop blowing dust back over the operator.

My '50 HT4 has a stock pusher fan. I put a pusher on my 7 U, she is a downhill puker. That way all that puke doesnt get in the fins and turn the dust into mud.

i have it written down in the truck but working off memory (bad idea) her badge says she's #7U22230 I believe. The D315 wears a different number 22207 and also has a tag from "Kersaw - Wheeler" in Salt Lake City Utah with an overhaul date of 1956!! Tag states bore, mains and rods are all standard as is the pony. I'll have to pull the exact S/N off the 315 to verify it's original application.

I find it really interesting trying to sort out the life history of things. Maybe she ran low on oil and spun a main/rod, maybe over heated trying to keep up with D6, maybe rod cap let go.......

I restored a mahogany Chris Craft 10 years ago and the boards and frames still had the pencil marks, signatures and "shop math" written on them. I'm very nastaligic and think this kind stuff is really cool.

I figered your D 4 was a high ser # ,To have a pusher fan on it .
As for fan types , I f you were driving down the road ,and air was actually being forced in the raditor ,and past the engine ,a puller fan is more efficent .
Crawer fan use is different ,the air is static ,and only moved by the fan on both sides of the raditor . A puller fan is drawing warm air through the raditor,heating this air ,and blowing it on the engine .A pusher fan is drawing cooler air past the engine and though raditor and dirverting it away from the tractor .
Cat has always maintained that pusher fans were more efficent . All the later track loaders,and crawer tractors either have pusher or reversable fans on them to push hot air and dirt away from the engine and raditor .
Reversable fans are the best fan ,so that in warm weather the fan can be a pusher ,and in cold weather the fan can be turned to warm the tractor and operator.
Try sitting on a D6,7, 8 9 in the summer with a puller fan blowing hot air,and dirt back at you and see how long it takes to get out the fan reversing tool to reverse that fan to a pusher !