Repeated Deck Bearing Failures

[adsm08 1,437]

So it just wouldn't be Spring if I didn't have to stop during mowing once or twice and rebuild the mower deck.

 

Last year at the Show I picked up an RM-366 that has, mostly, been working out well. Last week during mowing I lost the bearings in the triple-pulley. No big deal, they looked old, were of unknown age (probably older than me) and I had a whole other pulley assembly, with fairly new bearings that I installed myself, bought from Lowell, on my damaged RM-327.

 

I threw that pulley on, finished mowing, but the double belts on the deck weren't tight enough and ended up getting thrown and damaged. This weekend I pulled both decks apart, sharpened the blades (they were blunt) and put the also fairly new belts from the damaged deck on, re-tensioned the belts, and went to mow. The pulley bearings lasted less than five minutes.

 

I have two new sets of bearings on order, but I need to know if there is anything I should be looking at on this deck to find what's blowing them apart. Neither deck had a washer behind the pulley and the parts explosions don't show one. They also say both sets of bearings and the pulley are the same between the two decks.

[ri702bill 7,341]

Look again at the RM-366 Manual - in particular, part # 54 in the diagram. It IS the inner race spacer, WH # 6595 and MUST be used (and sized correctly).

That triple pulley has the "Classic" 2 ball bearing design - the spacer keeps the inner races stationary when the bolt is tightened. The outer race of the inboard bearing is compressed by the shoulder in the pulley so it revolves with the pulley. Now for the correct sizing - the spacer must be slightly long to keep the outboard bearing outer race away from the shoulder in the pulley. The outer race must be able to "float" in the bore.....

Running it with NO spacer puts the bearings under too much side load, gets worse when it warms up - premature failure.

One other thing to consider - the new ball bearings will have either seals or metal shields. Seals are easier to remove and reinstall - the idea is to flush the existing grease out and replace it with a GOOD high temp grease, like the green Lucas Xtra Heavy Duty grease. Helps them run smoother, longer, cooler....This is really important if they have seals - sealed bearings by their nature run hotter than shielded bearings.  The 366 and the 327 DO share a lot of common parts.

Best of luck with this - @peter lena is the grease guy; @Handy Don has a 366 he recently went thru.

Bill

 

Edited April 24, 2023 by ri702bill

[Handy Don 10,613]

17 hours ago, ri702bill said:

Best of luck with this

 

17 hours ago, adsm08 said:

So it just wouldn't be Spring

As fond as I am of the 854 and round hoods in general, the decks can be a challenge. I am mostly comfortable with mine now, but the face-to-bevel gearing between the floating cross shaft and the spindles gave me some extra work. It had too much gear lash due to wear (and unworn ones are VERY hard to come by) and it was quite noisy. Ultimately, I put it all together, measured the lash and then took it apart again to add an appropriate shim behind one of the face gears on the cross shaft to take most of the lash out (@ri702bill reminded me to leave some lash for grease and thermal expansion in use). It is quieter now, but will never sound like a deck without gears!

I was fortunate to get one very good triple pulley setup with clean and solid bearings (flushed and re-greased) so I haven’t yet had to pull one apart!

In case you haven’t noticed, there are two lengths of spindle--about ⅛” difference between them. The longer ones are intended to accommodate the thrust bearing that the later decks had under the bevel gear.

Edited April 25, 2023 by Handy Don

[adsm08 1,437]

I haven't looked, but I believe the spacer was there on the original pulley.

 

I KNOW it's there on the second one, because I know I put it back in when I did the bearings two years ago.

 

I have garage cleaning to do tonight. Maybe if I make enough headway with that I'll have time to pull the pulley again and check things out.

[ri702bill 7,341]

Good, but is it the correct length to let the outer bearing float?? You need to use a dial caliper to check the shoulder depth vs the stackup....sometimes, replacement bearings have a larger edge radius or the overall width is smaller - both can affect the stackup height.

Bill

[adsm08 1,437]

Well, I haven't had a bearing failure since April, but the belt from the engine to the deck has failed a few times this summer. It seems like when I get into thicker grass it almost binds up, and starts to slip that belt.

 

I think I've mowed for the last time for the year, so I'm just going to pull the whole thing apart and go through it over the winter.

[Handy Don 10,613]

13 minutes ago, adsm08 said:

Well, I haven't had a bearing failure since April, but the belt from the engine to the deck has failed a few times this summer. It seems like when I get into thicker grass it almost binds up, and starts to slip that belt.

 

I think I've mowed for the last time for the year, so I'm just going to pull the whole thing apart and go through it over the winter.

For sure, that single belt is the first thing to slip. Not a lot of options other than making sure everything is turning smoothly, that the pulleys are smooth, and the spring hasn’t gotten too weak.

I’m sure you also read in the manual that it wants the engine turning at full throttle--it needs the speed to get adequate torque out of those small pulleys! (I aim for about 3,300 RPM).

[adsm08 1,437]

4 minutes ago, Handy Don said:

For sure, that single belt is the first thing to slip. Not a lot of options other than making sure everything is turning smoothly, that the pulleys are smooth, and the spring hasn’t gotten too weak.

I’m sure you also read in the manual that it wants the engine turning at full throttle--it needs the speed to get adequate torque out of those small pulleys! (I aim for about 3,300 RPM).

 

Yeah, I know the engine needs to be spinning full speed. I think the last time I set up my throttle cable my tach was showing in the 3200 range.

 

There is definitely something else going on causing excessive drag because when I hit the thickest patch of my yard (which still isn't super thick) it can kill the engine.

 

I may very well just drop back to the 27 inch deck too. I bought the bigger one hoping to save a little time mowing, but I calculated it, it saves me about 2 laps.

Edited September 16, 2023 by adsm08

[peter lena 8,072]

@adsm08  sounds like you might have a combination of  issues , done a number of deck most important  thing , is every rotational point , must have the correct lubricant , and every part  of the related linkage / drive , has to move with total ease , my decks rotate easily  by hand at the mule belt  down slope to , the drive.. are you cutting at the highest setting ?  you have to think about deck discharge , sounds like you have a problem with that . as far as blowing things apart , never had that happen , does the pto lever , engagement squeal / make rough  engagement ?  maybe  there is a member close to you ?, that could verify  what you have going on .  has to be a glairing  /  functional engagement area , thats hiding in plane site. I can mention the entire set up of that unit ,  but if there is any part of it , that is holding it back in any way , it will you what is going on .  wish I could help , pete

[Handy Don 10,613]

3 hours ago, adsm08 said:

but I calculated it, it saves me about 2 laps.

👍

[adsm08 1,437]

2 hours ago, peter lena said:

@adsm08  sounds like you might have a combination of  issues , done a number of deck most important  thing , is every rotational point , must have the correct lubricant , and every part  of the related linkage / drive , has to move with total ease , my decks rotate easily  by hand at the mule belt  down slope to , the drive.. are you cutting at the highest setting ?  you have to think about deck discharge , sounds like you have a problem with that . as far as blowing things apart , never had that happen , does the pto lever , engagement squeal / make rough  engagement ?  maybe  there is a member close to you ?, that could verify  what you have going on .  has to be a glairing  /  functional engagement area , thats hiding in plane site. I can mention the entire set up of that unit ,  but if there is any part of it , that is holding it back in any way , it will you what is going on .  wish I could help , pete

 

So this deck is in use on my 855. The PTO is a foot pedal operation with a spring. Mechanically it has more in common with the belt tensioner on your car than with the lever-engaged PTOs on the later long-framed models. Everything is aligned properly. The spring seems strong, but is jerry-rigged at the frame attachment due to a hook breaking off. I have one on order, but they are back-ordered.

 

Height setting is on one of the lower settings, but I like to keep my grass on the short side to making cleaning up after the dogs easier, and the adjuster is stuck anyway. Raising it with the lift helps, but it didn't do this last year at the same settings.

 

Deck is rear-discharge and the whole rear of the deck is open and free. The rotating assembly seems to operate freely by hand, but like I said, gonna tear it down this year during the off-season and go through the whole thing. Probably replace all the bearings.

[Handy Don 10,613]

15 minutes ago, adsm08 said:

 

So this deck is in use on my 855. The PTO is a foot pedal operation with a spring. Mechanically it has more in common with the belt tensioner on your car than with the lever-engaged PTOs on the later long-framed models. Everything is aligned properly. The spring seems strong, but is jerry-rigged at the frame attachment due to a hook breaking off. I have one on order, but they are back-ordered.

 

Height setting is on one of the lower settings, but I like to keep my grass on the short side to making cleaning up after the dogs easier, and the adjuster is stuck anyway. Raising it with the lift helps, but it didn't do this last year at the same settings.

 

Deck is rear-discharge and the whole rear of the deck is open and free. The rotating assembly seems to operate freely by hand, but like I said, gonna tear it down this year during the off-season and go through the whole thing. Probably replace all the bearings.

I made one good deck out of three parts decks. When doing disassembly, of the “best” deck, I was shocked to find that one blade spindle had only one bearing. The lower bearing and its grease seal were just not there--there was a “bushing” of hard, dry grease in its place. 🫣 Can’t see that the bearing could have come out with the blade and blade holder in place, so can only assume someone was in there before me and forgot it on re-assembly!

Since spindle support plate was in the best condition, I did go ahead and use it with all new bearings and seals.

Edited September 17, 2023 by Handy Don

[peter lena 8,072]

@adsm08  BINGO !  sounds like your set up , combination of things , and lack of functional detailing is what is kicking your butt. first thing , is not just new bearings , but the easy seal removal , clean out ,and re greasing with  a hi temp grease , Lucas green or Lucas marine grease , both rated over 500 deg , polyurea rated , anti sling , your foot pedal PTO  set up is also in a dysfunctional set up , having gone step by step , on all my decks , until , every movement hand off  , works with total ease , you will continue to blow up . obviousely  this is not  a 1 and done , you need help on this , to correct and eliminate , issues . have any pictures of that  set up ?  hope another member close by , could contact , stop by , and verify  what you have , pete

[Handy Don 10,613]

18 hours ago, adsm08 said:

Deck is rear-discharge and the whole rear of the deck is open and free. The rotating assembly seems to operate freely by hand, but like I said, gonna tear it down this year during the off-season and go through the whole thing. Probably replace all the bearings.

I hesitate to offer this suggestion as you clearly know what you are doing, but...

Are you sure the blades are on in the right direction? Looking down from the seat the left blade turns CCW and the right blade turns CW. (This motion flings mushed grass against the center front of the shell which is why, when it is not cleaned regularly, that that part of the shell rots first.)

Edited September 17, 2023 by Handy Don

[adsm08 1,437]

1 hour ago, Handy Don said:

I hesitate to offer this suggestion as you clearly know what you are doing, but...

Are you sure the blades are on in the right direction? Looking down from the seat the left blade turns CCW and the right blade turns CW. (This motion flings mushed grass against the center front of the shell which is why, when it is not cleaned regularly, that that part of the shell rots first.

 

 

That is one thing I need to check. I THINK they are on correctly, however I suffer from a touch of dyslexia and get things reversed easily when I'm flipping and flopping them all over the place.

[Handy Don 10,613]

1 hour ago, adsm08 said:

 

 

That is one thing I need to check. I THINK they are on correctly, however I suffer from a touch of dyslexia and get things reversed easily when I'm flipping and flopping them all over the place.

You could ask me how I know to check this and I would look at the ceiling and smile ruefully.

[adsm08 1,437]

27 minutes ago, Handy Don said:

You could ask me how I know to check this and I would look at the ceiling and smile ruefully.

 

 

The reason I think they are on correctly is because the belt was slipping and the deck almost stopping on the first mow of the year, so I took them off and got them sharpened, put them back on, and that issue stopped, until the first bearing failure.

 

I have found new replacement blades for this deck as well, albiet a bit pricey. I may just put back a few dollars each month through Winter and get brand new ones for Spring since they don't seem to hold an edge great.

 

I had my neighbor who does tractor/lawn equipment repair sharpen them the first time, and I've had to dress them twice. All that in a season where I haven't used 5 gallons of fuel for mowing.

[Handy Don 10,613]

3 hours ago, adsm08 said:

they don't seem to hold an edge great

Makes me wonder what you are mowing? My mower never slows even when taking off 2 or 3 inches of thick springtime grass in 2nd gear. And the blades are still sharp after a full season of mowing my, admittedly modest, quarter acre of grass--maybe 10 outings so far.

 

If you are cutting very low, 1.5-2” for example, you are definitely getting grit and soil blown up onto the grass that is going to hurt your edges. Also, some grass varieties are very tough (St. Augustine for example). I cut at the second highest stop, 3”.

 

If the blades were sharpened with a grinder, they almost certainly have lost some or all of their temper which softens the edges--the shops near me (and I) sparingly use a bench-mounted belt sander.

[adsm08 1,437]

8 minutes ago, Handy Don said:

Makes me wonder what you are mowing? My mower never slows even when taking off 2 or 3 inches of thick springtime grass in 2nd gear. And the blades are still sharp after a full season of mowing my, admittedly modest, quarter acre of grass--maybe 10 outings so far.

 

If you are cutting very low, 1.5-2” for example, you are definitely getting grit and soil blown up onto the grass that is going to hurt your edges. Also, some grass varieties are very tough (St. Augustine for example). I cut at the second highest stop, 3”.

 

If the blades were sharpened with a grinder, they almost certainly have lost some or all of their temper which softens the edges--the shops near me (and I) sparingly use a bench-mounted belt sander.

 

 

And I don't know their history. Someone may well have used a grinder at some point. I bought the deck very used at last year's show, and they are well worn. Like I said, I'm going to look into replacing them before next spring.

[adsm08 1,437]

I had an above average pay check this last pay period, so I got new blades and just finished mowing with them for the first time about an hour ago.

 

The blades were the problem. I cut the thickest stuff in the yard without an issue.