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-   -   2188 sieves driveshaft pulley looseness (https://www.thecombineforum.com/forums/7-case-ih/332981-2188-sieves-driveshaft-pulley-looseness.html)

Chris2188 07-05-2019 05:35 PM

2188 sieves driveshaft pulley looseness
 
Hi everyone,

I have just noticed a slight looseness on the off centre pulley that fits onto the shaft running the 5 augers beneath the rotor. I recently rebuilt this and was surprised to find this looseness. After taking off the off centre pulley i noticed the key fits the shaft but doesnt fit the pulley. I compared this to the old drive shaft and pulley before i rebuilt it and the situation is the same. Is the key meant to be smaller than the slot on the pulley? I only seem to be having this problem on the left side.

Thanks for your tips.

Best

Chris

marshall 07-07-2019 10:07 AM

Funny but haven't had that problem but had the clutch plates get loose and had to use some devcon plastic metal to tighten things up as I could hear a noise when the sieves would change direction and the shaft would jump just a bit . I know that the hub doesn't sit that tight on the shaft but haven't seen it wear that much , could you make an oversize key ? But that won't last too long as it couldn't take all that load for very long - Maybe some epoxy metal ?

schraefel 07-07-2019 11:33 AM

Does it call for a step key? I can't remember. Have had a few off in the past. You'd think it should be tight. It takes quite a pounding.

RunninREDharD 07-07-2019 01:29 PM

Change the shaft and the bearings. I have had this situation and there was a "tick" coming from the bearings and shaft. I ignored it as bearings appeared to be okay on the eccentrics. Having a hex shaft and looseness slams the sieve system hard. My first experience with this was. a broken bolt and later broken sieve rail due to stress likely caused by broken bolt. It also pays to make sure any shaker bushings that are damaged to be changed out ASAP, don't leave until the end of season. Sieves themselves will also breakup. Microscopic wear on that hex shaft is very detrimental. You want to save a lot of money in the long - change that hex shaft!

This is more applicable to the long sieve system. Increasing the length of sieve system puts more stress on the old system than it was originally designed for. The additional wall support for the needle bearings were again a byproduct of additional sieve length.

When you change everything out, make sure that the bearings are mounted square to each other in the system. There was a jig to make sure you get proper placement of those bearings in the "cheeks" of the combine. Having the system stroking at a bias to each other leads to quick failure of sieve hangers, bolts and bushings. I made my own jig which I borrowed from my local CaseIH dealer to get it right.

Transaxial 07-07-2019 03:32 PM

Quote:

Originally Posted by RunninREDharD (Post 3344285)
Change the shaft and the bearings. I have had this situation and there was a "tick" coming from the bearings and shaft. I ignored it as bearings appeared to be okay on the eccentrics. Having a hex shaft and looseness slams the sieve system hard. My first experience with this was. a broken bolt and later broken sieve rail due to stress likely caused by broken bolt. It also pays to make sure any shaker bushings that are damaged to be changed out ASAP, don't leave until the end of season. Sieves themselves will also breakup. Microscopic wear on that hex shaft is very detrimental. You want to save a lot of money in the long - change that hex shaft!

This is more applicable to the long sieve system. Increasing the length of sieve system puts more stress on the old system than it was originally designed for. The additional wall support for the needle bearings were again a byproduct of additional sieve length.

When you change everything out, make sure that the bearings are mounted square to each other in the system. There was a jig to make sure you get proper placement of those bearings in the "cheeks" of the combine. Having the system stroking at a bias to each other leads to quick failure of sieve hangers, bolts and bushings. I made my own jig which I borrowed from my local CaseIH dealer to get it right.

I agree that any component in the sieve shaker system that gets even a tiny bit loose sets up a vibration or pounding and quickly starts a chain reaction of metal fatigue and destruction. I have had a couple of major self destruct events on 1986 era short sieve 1680s and once on a 1993 1688 with the newer long sieve and cross flow fan. I am not sure what the weakest link is in these sieve systems and it could be anything, but one place to start is to change ALL the rubber bushings in the whole sieve hanger and drive before they become loose and start to pound. My experience was to change the rubber bushings before 1500 hours. That seemed to be the magic number where failure started to happen. Try to catch it the winter before it happens. Be careful when installing the bushings and torquing the bolts to have the stroke in the middle of the range of movement of the rubber bushing or it will tear the rubber and fail prematurely. There is a special tool for pressing the bushings in to keep them going straight and not damage the steel sleeve or the rubber when pressing in. I made my own. Just a pin 3" long that fits the ID of the bushing that is turned down from a larger pin, also about 3" long, that is just under the OD of the bushing outer sleeve.


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