CIH 1660...

Dave H (MI)

Well-known Member
Early serial number. Can someone explain to me the mechanics of the fan control pulleys? You operate the speed control switch in the cab and the upper pulley has a threaded rod which mechanically moves it in or out. I don't see what this accomplishes. The belt gets floppy when the speed is moved to slow and the fan does slow down. But I cannot get the speed over 800 and I do not see how to do this. The nuts on the threaded rod are all the way to the end. What is supposed to happen with the belt and the pulleys that accomplishes the speed change?
 
If your belt gets floppy, EITHER:

1) The belt needs replaced.

2) The bottom pulley is not closing as it should. (May need taken apart and cleaned.)

3) Something is out of adjustment at the top pully, allowing pulley to open too far.

The belt should never run floppy.

If you can only get 800 r.p.m., you need to see if the belt is running flush with the outside diameter of the top pulley. If the belt is down inside the top pulley, try to adjust the locknuts on the threaded rod so you can achieve a "flush" condition. If you don't have enough adjustment to get the belt flush, you need a new belt.
 
Mine is a late serial #, but I am assuming they are very similar. When I got mine I found three bushings in the lower sheave badly worn, such that the moving half didn't want to move!
 
Dave,
One pulley will be operated by the threaded rod attached to a motor, and one sheave of the other will be under spring pressure. As the motor turns the threaded rod one sheave of that pulley moves in or out. This changes the diameter of that pulley. Because the belt is fixed length and the other pulley is spring loaded, the sheave on the driven pulley moves and changes diameter of the pulley. When the belts wear you can't get to full speed, the belt will be thinner than a new one and won't be wide enough to fill the pulleys.
Josh
 
Do you mind me asking? What exactly is a "sheave" in this application? I apologize but I do not remember seeing anything just like this in the past. These two pulleys are not solid castings like I am used to but would appear to be split into two halves. The top one the halves appear to come apart with the movement of the threaded rod and the belt is well down between them. The bottom pulley does not appear to move apart like the top...or at least it is not that way at the moment. I'm not sure how this changes the diameter, unless of course the two sides coming together squeezes the belt out to the outer diameter as mentioned below? I think I am getting this...but not quite there yet.
 
I will get it up to full speed tomorrow and look at that belt as relates to the top pulley outer diameter. I am confused on what the bottom pulley does. The upper one clearly spreads apart and closes as the threaded rod is adjusted. The bottom one does not have an adjustment that I can see. Does the movement of the belt to the outside diameter of the top pulley open up the bottom one? Trying to get my mind around it. Can't fix something if you don't know how it works in the first place! Thanks to all!
 
The words sheave and pulley might be interchangeable in your mind. The sheave halves move either closer together or farther apart which changes the diameter because the belt rides either deeper or shallower in the sheave halves.
 
Yep, as the top pulley or sheave or whatever you want to call it squeeezes together, the bottom one should open under spring pressure.

Then when you open the top one, the lower should close-again because of the springs on the bottom pulley forcing it closed.

Once you get this figured out, the rotor belt is gonna be a breeze.
 
NOW I am getting it! So in terms of the belt, it is one of these belts with the big square teeth on the bottom and these look like new. But would it be safe to say that the WIDTH of this particular belt is going to determine wear rather than the condition of these square teeth?
 
Now I am getting it! Thanks!

I had been working on the lights on this combine. A couple of circuits are not working and I thought it would be easy to diagnose once I had the schematic. Had to let that go...taking too much time. On my top ten list of idiot things I would question why it is that, going back to their earliest history, IH decided to paint over EVERYTHING on their equipment. Including the color coded wires that you need to trace to fix electrical issues. Every wire on the outside of the combine is one color...red.
 
Yes! You got it! If the width of that belt is off it messes with the ratios. The adjustable pulley (sheave) has an infinite number of settings. One should let the belt set clear down in the pulley until it almost bottoms out on the center shaft, and the other extreme would put the belt flush with the outer diameter of the pulley. The belt should constantly stay tight because the spring in the other pulley takes up the slack. Take the belt off and use a long pry bar to see if you can spread those pulley halves (on the spring one). If you can't then it needs to be taken apart and inspected. I always replace belts long before they probably need it and keep the old as a backup. There's nothing worse than breaking a belt on a Sunday at 4:00.
 
The sheave is half of the pulley. If the lower pulley is not moving, something is wrong in the lower pulley. One half is fixed, the other half should be free to slide and be held tight against the belt by a spring.
Josh
 
Got it! Made sure it was all working the way it is supposed to. Did not want to start doing adjustments without understanding how it worked. Once I got it then I went ahead and made the adjustments. It now runs up to 1000 RPM and works as she should.

I figure she is about as ready as she is gonna be for the "test plot" of corn so I am putting it all back together and switching over to the scrap iron...er...corn head that I bought last week. Lots of worn parts to replace and I am going to poly the trough. After that I will be at my leisure to slave away at something else!

Thanks to all once again!
 
I will also guarantee that your fan throw out bearing needs to be replaced. They need to be replaced every year. A bad bearing will also cause you to not get full RPMs on your fan. You should get close to 1100 RPM. If you look on your threaded fan adjustment rod there is a block that moves back and forth as the adjusting motor turns the rod. On the top and bottom of this block there are two bolts. Take these out and swing the arm away from the top pulley. The bearing will be located on the outside of the top pulley. Be careful when you take the two bolts out as there are small bushings on them that are easily lost on the ground
 
"I will also guarantee that your fan throw out bearing needs to be replaced. They need to be replaced every year."



You should not have to replace that bearing every year,I typically get at least 10 years out of them.

What many people do not realize is that you need to over grease the top outer moving sheave so grease boils out between the sheave outer end and the shaft. Get a thumbnail size glob of grease out there, and when you start the threshing parts, it will sling that glob of grease out into the thrust (throw out) bearing where it works between the inner and outer bearing races to lubricate it. Do that and the thrust bearing will go for years. Been doing that with my 1480's for near 30 years.
 
Like this, it will lubricate the thrust (throw out) bearing which should last near 10 years of 500 or so hours per year.
a170061.jpg
 
Not sure it needs it yet. I have 1000 RPM and plenty of thread left for adjustments. Glad to have the info on how to get to it though! Likely it was NOT greased as mentioned below so probably going to need a new one afore long!
 

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