Winter Fan for D4D

[Metalman 55]

This past spring I sold my Ser #78A5667 D4D dozer to a man quite a distance away. I kept the winter fan & shipped the machine with the summer fan on it. My parts book went with the machine so I cannot help him with identifying the proper fan. The attached photo is the winter fan that I kept, however I cannot find any part numbers on it. Wondering if someone can look up the part # for a winter fan & I will pass it along to him? Apparently he ordered what he thought was a winter fan but it appears to be wrong from what he said. Thanks

 

[kshansen]

This one does not come up on my SIS, says 78A is not a good number.

Cat is usually pretty putting numbers on parts I'd give it another look, maybe a light sanding with fine emery or Scotch-brite pad?

 

[Metalman 55]

That's strange.......... I don't have the machine anymore but I am pretty sure that is right & Ritchiewiki says the 78A series was discontinued in 1967.

http://www.ritchiewiki.com/wiki/index.php/Caterpillar_D4D_Crawler_Tractor

 

[DPete]

I just bought a 78A 5716, haven't even got it home yet, produced from 63' to 67'

 

[mitch504]

You don't just turn the fan around?

 

[old-iron-habit]

You don't just turn the fan around?

No, the curve would be backwards. Some are spring loaded to pull each blade and rotate 1/2 turn.

 

[old-iron-habit]

This past spring I sold my Ser #78A5667 D4D dozer to a man quite a distance away. I kept the winter fan & shipped the machine with the summer fan on it. My parts book went with the machine so I cannot help him with identifying the proper fan. The attached photo is the winter fan that I kept, however I cannot find any part numbers on it. Wondering if someone can look up the part # for a winter fan & I will pass it along to him? Apparently he ordered what he thought was a winter fan but it appears to be wrong from what he said. Thanks

Are you interested in selling your winter (suction) fan?

 

[Old Magnet]

78A fans
Fan (suction) 9H9766
Fan (blower) 9H9828

 

[kshansen]

You don't just turn the fan around?

Mitch are you joking? I did have a working group leader at the shop that tried to tell me that would work.

If not joking I guess I need to explain it like I have to others in the past.

You need to understand that a fan or propeller is for all practical purposes a very short screw that moves air by "threading" itself into the air.

Now think of the air as a nut and the fan blade as a very short piece of all-thread. If while holding the nut still and you un-thread the the all thread from the nut and turn it 180º and now try screwing it in the nut and you turn it the same direction as before the nut will move in the same direction. It does not matter which end of the threaded rod faces the nut turning clockwise will move the nut in the same direction.

Now as I'm sure OIH would tell you turning fan around will make some difference as the curve of the fan, if run facing the wrong way, will cause a loss of air flow but it will still be moving in the same direction.

And if anyone has one of those spring loaded reversible fans be very careful to get all blades set for the same direction of air flow. One blade set the wrong way will cause over heating on a warm day. Seen that one first hand!

 

[CavinJim]

No, the curve would be backwards. Some are spring loaded to pull each blade and rotate 1/2 turn.

It's more like 1/4 turn if I remember. 1/2 turn would be 180 degrees--which would be like turning kshansen's all-thread around, the angle is still in the same direction. 1/4 turn, or 90 degrees, reverses the angle.

 

[Metalman 55]

You don't just turn the fan around?

Ken is right.........I tried that once many years ago & it didn't work. If I remember correctly it seems to me that by reversing it, it hardly moved any air.

 

[Metalman 55]

Are you interested in selling your winter (suction) fan?

I had better hang onto it for a while yet, as I have hopes of finding a donor engine for this D4D that currently is not running. The engine in this one spun a rod bearing & ruined the crank before I bought the machine.

 

[Birken Vogt]

Ken is right.........I tried that once many years ago & it didn't work. If I remember correctly it seems to me that by reversing it, it hardly moved any air.

I recently looked at a machine that some dummy had "reengineered" and put an electric car fan out of the junk yard on it. Pretty stout fan and it moved a respectable amount of air. Trouble is the fan cup was backwards. No problem, they just reversed polarity and it runs backwards. I disagree somewhat with the statement above. This one moves plenty of air in the reverse direction. No easy way to change it so I just said, probably good enough, I did not design this hunk of junk, call me back if it overheats, and they never have, so I guess it works.

 

[CavinJim]

I disagree somewhat with the statement above. This one moves plenty of air in the reverse direction.

Apples and oranges here. There is a considerable variation in fan design--some will work just fine running backwards, others will not. Typically, fans that are designed to maximize airflow in one direction do not work well when reversed. Fans that have less investment in design (that is--"just enough will do") won't be nearly as efficient in the intended direction but will work well enough in either direction. The electric car fan mentioned is probably more than enough in it's designed direction and just OK in reverse. An ideal design would be a fan that would be OK in either direction but never more than enough.... If I remember correctly, the diesel cycle is more efficient the hotter it runs--make the engines out of ceramics and throw away the radiator. In reality, you want just enough cooling to keep the oil from deteriorating too fast. But that's another story from when I was an undergraduate working on a research project for Koppers. Just add some oleic acid to your oil....

 

[Metalman 55]

78A fans
Fan (suction) 9H9766
Fan (blower) 9H9828

Thanks for the information.....much appreciated.

 

[kshansen]

But that's another story from when I was an undergraduate working on a research project for Koppers. Just add some oleic acid to your oil....

Koppers! That's a flash back if it's the same Koppers I am thinking of as they were one of the previous owners of the company where I worked for 40+ years.

 

[kshansen]

Ken is right.........I tried that once many years ago & it didn't work. If I remember correctly it seems to me that by reversing it, it hardly moved any air.

Depending on how involved a design a fan blade it will make a major difference or only a minor difference. Some blades can be so simple, basically almost just a flat piece of steel at an angle. While others are designed almost like a wing on an air plane using an air foil design.