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wwbragg

Sickle bar shake down

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wwbragg

OK - - -time to call in the experts---

I just completed the repower on my Simplicity 725 and hooked up the sickle bar.  When activated, it shook so badly I thought my fillings were going to come loose. 

The bearings in both idler pulleys were toast so I replaced them.  Then I took the drive unit apart (numbers refer to items in the Drive Group picture) and found the head of the bolt (#16) on the crankshaft (#10) was hitting something and the pulley was rubbing a grove in the hinge (#60).  There was an extra washer (#3), two on each side of the lift bracket (#5).

I rearranged washers (#3) according to the layout, one on one side and two next to the pulley and everything clears but the pulley barely fits onto the shaft.  After reassembly and applying power, the woodruff key worked its way out and allowed the pulley to spin freely.  Apparently, because the pulley’s set screw doesn’t go to the middle of the woodruff, when I tighten the set screw, it dislodges the woodruff.

Do I have the correct pulley?  It is 6”.

What have I forgotten?

What else would cause the shaking?

sickle bar drive group.gif

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GregB

+1 on the above.  find a copy of the operators manual.  Engine speed to be a slow walk in first gear or second gear, if my memory serves....

 

But it is not what it used to be...............

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wwbragg

Yeah, they say memory is the second thing to go.  I don't recall what the first thing was.

Half speed - -  then I slowed it down even more.  Feels better but the Woodruff came out again.  How can that even happen?  The pulley's groove and set screw should hold it in place.

Anybody know the specs on the pulley groove?

Edited by wwbragg
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spi

I'm having the same problem. Out of frustration I tacked the pulley to the shaft #10 and it's worked although I hate mickey mousing things like this but had to get the field mowed. I have been considering drilling it and using a rolled pin in it. I'll start hunting for that key too.

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wwbragg

I thought of that but not for long. 

The guy who had the tractor before me, simply screwed the set screw in real deep and ran it that way. 

 I ordered a key on ebay (914-0126 Hi-pro Key 3/16 x 3/4 - Snowblowers, Mower Spindles, Etc. OEM New MTD).

 

The specs seem to be correct- - -I'll let you know if it fits.  The picture gives the measurements from the shaft & pulley:

59adfbff8aed5_hi-promachinekey.thumb.png.3ed437c384d16d9ab2df178a8bdbcd96.png

Edited by wwbragg
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spi
22 hours ago, wwbragg said:

I thought of that but not for long. 

The guy who had the tractor before me, simply screwed the set screw in real deep and ran it that way. 

 I ordered a key on ebay (914-0126 Hi-pro Key 3/16 x 3/4 - Snowblowers, Mower Spindles, Etc. OEM New MTD).

 

The specs seem to be correct- - -I'll let you know if it fits.  The picture gives the measurements from the shaft & pulley:

Cool, good luck with that.

It seems like every two hours something breaks or rattles loose. One time the bearings #4 in the diagram came apart and gouged the shaft # 10, had to have it welded up and turned down once I got new bearings for it. I thought the shakedown would be long and eventually would replace everything and be good to go. Now I'm beginning to wonder.

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wwbragg

OOPS!  Premature.  It fits, but the pulley still slides off and even though the key was tight in the shaft, it comes out.  I tightened the set screw down until I thought I would twist the allen wrench.  I think the pulley is defective.  Any ideas/suggestions?

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wwbragg
1 hour ago, B-16_IC said:

Is the set screw over the key? 

Just barely.  It hits right at the outer edge.  My son, an aerospace machine maintenance mechanic says the set screw is worn off.  He is going to drill & tap another set screw hole.

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wwbragg
3 hours ago, spi said:

Have you had any problems with those roller bearings?

No, but I haven't had a chance to actually cut grass with it; why with all that shaking and all.  But based on what you said about something breaking in two hours, I am going to pull the bearings from the old bracket and set them aside just in case.  The original bearings are 60's/70's vintage TIMKIN, made in USA.  They should be pretty tough if properly lubed. But I never trust a previous owner to have pulled proper maintenance.

Regarding your bearings, I try to start at the problem and work backwards, inspecting things and motions as I go.  Is the shaft (#10) perfectly smooth?  Is it perfectly round?  How about the pitman housing (#11) and the pitman bearing (#14).  If you are going to replace the #4 bearings, you might as well replace #14 while you have it apart.  The further upstream I go, the more problems I find.  And everything contributes to the final symptoms.

Good luck with yours.

Edited by wwbragg
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