DR trimmer/mower: what could be binding?


  #1  
Old 07-30-22, 04:51 PM
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DR trimmer/mower: what could be binding?

DR trimmer mower.
6HP electric start Briggs engine on the Pro Model from June 2002.

Serial number 47061.
engine number 122H07-0126-B1 02052256.

I just fixed the drive pulley on the engine shaft falling off.
now it stalls about 1 minute after engaging the mower .

It stops abruptly like something is binding.
engine runs fine at full throttle. Runs fine when the mower is engaged. Then it stalls.
I disconnected the brake, i guess it is. Stops the mower from spinning after you dissengage it. I wanted to see if maybe it needed to be adujsted. But it stalled with the brake removed. I took the mower ball off and the mower pulley. Both are spinning freely.
any idea about what will bind after 1 minuite?
it has two sets of bearings in the mower ,on the mower pulley. They both spin freely. Can bearings bind when they heat up?
 
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Old 07-30-22, 05:29 PM
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Can bearings bind when they heat up?
YES! But that doesn't necessarily answer your question. And in my very limited knowledge I don't think that is your problem.
 
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Old 07-30-22, 05:40 PM
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Generally if they are so bad that they can bind enough to stop the engine, then they won't be free turning by hand afterwards. If you hear and feel a gritty rumble when you turn that pulley, then the bearings could possibly be the problem but hard to say. All there is, is an engine pulley, the mower pulley, and a small tensioner pulley, right?
 
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Old 07-30-22, 05:43 PM
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Could it be that you may have a bent shaft? Did you recently hit a rock or heavy tree root?
 
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Old 07-31-22, 03:44 AM
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How long will the engine run without engaging the mower?
 
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Old 07-31-22, 06:25 AM
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If the problem just started with the work you did on it, most likely that's where you need to look for the fix. Maybe you left out a shim washer or over tightened a nut. If it runs for a minute then binds, something should be hot.
 
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Old 07-31-22, 07:04 PM
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I agree, very hot if it's binding enough to stall.
 
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Old 07-31-22, 07:48 PM
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Two tensioner pulley and a rubber block to stop the mower from spinning, but yes that is all there is
 
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Old 07-31-22, 07:52 PM
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Haven't hit anything.
I would think a bent engine would stall at high RPM without the mower engaged. The mower shaft spins freely by hand with the drive belt disengaged. I would if it was bent I would see it.
i did just replace the engine pulley. I suppose I could try putting the old pulley back on and see it if still binds. Just to eliminate a bent new engine pulley.
 
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Old 07-31-22, 07:54 PM
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I assume the engine will run untilll it runs out of gas without the mower engaged. I have run it for a minute or two with the mower disengaged without a problem
 
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Old 07-31-22, 07:56 PM
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I will run untill it stalls and check for heat.
 
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Old 07-31-22, 08:02 PM
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Drive pulley part
 
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Old 07-31-22, 08:03 PM
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Mower puller
 
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Old 08-01-22, 02:10 PM
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If the engine runs fine without the mower engaged and the mower driveshaft spins freely without the belt attached, the only things left are the belt and brake. Is the diameter of the new and old pulley the same? How is the belt pulley located vertically on the motor shaft? What controls the rubber block mentioned in post 8? What establishes the distance of the motor shaft to the mower shaft?
 
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Old 08-01-22, 11:43 PM
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Belt is new, from the manufacturer.
Brake has been disconnected to eliminate it as a possibility.
Old and new pulleys are the same size but I'm going to try putting the old pulley back on and see if it still does it. Maybe the new pulley is defective and has too much weight on one side, or something.
The rubber block brake is attached to the linkage that engages the mower. The brake engages the mower pulley when the mower control bar is release and disengages when the bar is pushed down.
Distanced between motor shaft is mower shaft is set by the mower deck. Two tensioners put pressure on the belt to activate the mower.
Not sure what you mean by " How is the belt pulley located vertically on the motor shaft".
 
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Old 08-02-22, 07:43 AM
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Maybe the new pulley is defective and has too much weight on one side
It wouldn't be that. Something is either too tight or doesn't have the clearance it needs. Do both the old and new pulleys have the same length of bore through them?
 
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Old 08-05-22, 04:21 PM
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Found the problem, but cant figure out how to fix it.
I will attach photos.
the mower is a pulley sandwiched between two metal plates. 1 plate blots to the trimmer deck, belt goes on the pulley, then you bolt the lower plate to the top plate. Each plate has a bearing in it and each end of the pulley shaft goes into the bearings. The head that holds the string for trimming is bolted to the center of the pulley shaft. They use the action of bolting both plates together to press the pulley shaft into the bearings. Unless the shaft is supposed to fit easliy and my bearings shrunk.
When I checked on it today, the mower pulley was jammed. Took it apart, took the pulley out. Checked the bearings. Everything is free and spinning.
one thing I do not understand is what caused the pulley to jam, stall the engine, then free itself when I checked to see what was jammed. Obviously, the last time it stalled and I put it away for the night, it stayed jammed.
after checking everything and putting it back together, I felt the bolts on the second plate were harder than they should have been to tighten. Checked the pulley and it was jammed .
A logical assumption would be I have a plate upside down or put something back together wrong. But I dont see it.
the only problem I noticed was the top plate is warped. I dont think that would jam the pulley.
I might have to buy the whole assembly ,both plates and the pulley, to replace the one warped plate, which would solve the problem.
but if anyone can look at my photos and the schematics and figure this out and save me some money, I would appreciate it.
 
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Old 08-05-22, 04:49 PM
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Two plates separated

Plates together, but not bolted tight


Plate that goes on the bottom. The side you are looking at faces the ground

this is the top plate. The side you are looking at goes against the mower deck

 
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Old 08-05-22, 04:52 PM
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I just noticed while taking the photos, the bearing on the bottom plate is making noises while spinning. If the bearing is shot, would it bind when pressed onto the pulley shaft, but spin freely when not on the pulley shaft?
 
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Old 08-05-22, 06:47 PM
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When you bolt the two plates together tight can you move the pulley side to side? It should have some play
 
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Old 08-05-22, 07:06 PM
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The flanges on the bearings should go against the pulley. But when you assemble it push the bearings into their respective cases. Make sure the flange is tight against it's case. Don't use the pulley to seat the bearing.
 
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Old 08-05-22, 07:55 PM
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Another thing those bearings are sealed bearings. They are pregreased. The bearing you show viewing from the bottom is open and no grease. It can't run like that.
 
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Old 08-06-22, 04:45 AM
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In reading all this again I see where you have a warped plate. Likely the assemblage of the bearings/pulley is too long for the cases,. When tightened that warped the case and pinched the pulley causing the problem. You have it assembled wrong or there's a faulty part.
 
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Old 08-06-22, 06:06 AM
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Help me get oriented. Does the mower pulley assembly top piece (#36) get bolted to the mower deck (#28) using the 4 hex bolts (#44)? The mower pulley assembly bottom piece (#37) get bolted to the mower pulley assembly top piece (#36) using the 4 flat head bolts (#30). My guess is piece 37 is more rigid than piece 36 or piece 28, it will dictate alignment. When assembling, you should tighten bolts 30 before 44.
 
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Old 08-06-22, 08:28 AM
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Marbobj-
There is no play.
pulley will not move when everything is bolted together.
i can seat the bearings by hand, the pulley shaft will not go into the bottom pulley by hand.
i believe both bearings are open on one side. But I will check.
beelzebob-
yes, you have it right. That is how it goes together.
i haven't tried putting it together like that yet. It would be harder to do that way, but I will try it. Your way the is to assemble the whole unti first, then bolt it to the deck as one unit.
I have been bolting the top plate to the deck first, with the pulley, then the belt, then the bottom plate.
 
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Old 08-06-22, 09:10 AM
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If the. Bottom is warped the bearing is cocked and would receive the shaft poorly if the pulley is tight when assembled there is no point running it. You have to have clearance. If those bearings are open on one side check to make sure they are the correct bearing. They should be fully shielded both sides.
 
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Old 08-06-22, 09:18 AM
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I may have figured this out.
I just checked. The pulley shaft is stuck in the top bearing. The bottom bearing is stuck on the pulley shaft. the bottom bearing is a tight fit into the bottom plate. I turned the bottom plate around backwards and the bottom bearing sllid in easily.
I wonder if I have tapered bearings and I put them in backwards?
do you think if tightening bolts forced the pulley shaft into the bearings and forced the bearings into the plates, that would squish the bearings just enough to squeeze the the pulley shaft and jam the pulley?
I can't test this theory today, I have to go to work, but first chance I get I will take it all apart and check both bearings and see if they go into the plates, and if the pulley shaft goes into the bearings, easier one way than the other.
Am I correct in assuming If I am right, I should buy new bearings?
 
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Old 08-06-22, 09:47 AM
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Those are ball bearings and no taper. They should be shielded on both sides to avoid dirt intrusion.
If the bearings have to be forced onto the shaft, tough up the shaft with a little emery cloth

If the lower casing fits better inverted, is there a chance you had installed it up side down?

I would get two new bearings fully shielded. Then assemble it by hand and touch up the shaft as needed, but don't over do the polishing. With it assembled and bolts tightened the puley should move freely. If it doesn't you may have to use shims or get a new assembly to get you going. You would just have to evaluate the cost benefit of all of it yourself.
 
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Old 08-06-22, 12:51 PM
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You can't invert the casing. Only fits one way. When it is off the mower you can invert it. But you can't bolt it together inverted.
Maybe they tapered the race?
They may have done something so the bearing only fits one way.
As I said, I'm going to take it all apart and see if it fits together one way, but not the other wayI will also try the emery cloth.
I'm also going to ask product support if there is only one way to install the bearings.
It will be a few days before I can work on it again. I will post what happens .
 
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Old 08-06-22, 01:12 PM
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The bearings aren't tapered. It looks like your bearing isn't seating all the way down on the shaft and it's bunding when you put the pieces together. In the first pic the bearing doesn't look like it's all the way down. Seems like those should be sealed bearings.
 
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Old 08-06-22, 03:19 PM
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The bearings in the mower pulley assembly are a press fit, OD and ID, to insure the bearings outer race doesn't rotate and the inner race rotates with the mower shaft. The mower shaft threaded end should be below the mower pulley assembly bottom bearing so that tightening the string spool on the mower shaft threaded end doesn't apply any pressure to the mower pulley assembly . The pulley of the mower pulley assembly should be centered between 36 and 37. Does the pulley attach with a set screw or is it pressed on to the mower shaft?
 
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Old 08-06-22, 05:36 PM
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That's pretty much what he's doing, pressing the bearings on the shaft with the pulley in between. His problem is what he winds up with - the pulley locked up. It's an indication he has too much stuff in too small a space. The three parts in that space are the two inner races and the pulley. He needs to pick up tolerance in the ball bearing/races and it's jammed up. What he could do is shim the two cases apart slightly.
 
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Old 08-06-22, 05:41 PM
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That application wouldn't need a press fit since it has belt tension. A slip fit would do,
 
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Old 08-07-22, 04:15 AM
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The assembly drawing for item 118 shows the bearing flanges on the outside of pieces #35 (identified as #37 in my earlier response) and #36. Is this what you have? This results in maximum vertical space for the pulley in the mower pulley assembly.
 
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Old 08-07-22, 05:57 AM
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Yeah the drawing shows the flanges on the outside of the cases, doing that would take care of the clearance issue. But it takes him back to the original problem. Is this the pulley that fell off. Is so did the shaft fall out the bottom of the casing. Seems an odd setup but that would have a pressed everything to hold it together. Wondering if the lower bearing pushed out in the original break down. He may need a new assembly.
 
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Old 08-08-22, 10:16 AM
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What happened to xfrank12? Hope everything is OK.
 
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Old 08-12-22, 12:14 PM
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Beelzebob-"the pulley of the mower pulley assembly should be centered between 36 and 37. Does the pulley attach with a set screw or is it pressed on to the mower shaft?"
if you are asking about pulley #38, the only thing holding it in place is it is sandwiched between the two flanges. When the flanges are bolted together, the pulley cant move up or down. It can only spin.
 
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Old 08-12-22, 12:18 PM
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Beelzebob- "The assembly drawing for item 118 shows the bearing flanges on the outside of pieces #35".
the bearings fit easily that way or can be pressed fit on the other side. I have tried reassembling both ways.

 
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Old 08-12-22, 12:23 PM
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Marbobj- no, this is not the pulley that fell off. The problem started with a trimmer head bolt replacement. While working on that the drive pulley fell off the engine and I couldn't figure out what held it on because the washer that held it on was worn down to half its size.
the problem with the trimmer head started when I put it all back together
 
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Old 08-12-22, 12:25 PM
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And yes, im ok. But the trimmer still doesn't work.
 
 

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