ASM Gear box problems

[Farmer Bob]

I have had an ASM saw mill for two years and in that time have had to replace the gear box 15 times. The mill manufacturer suggested it could be the belts being too tight but this has been dismissed by several Engineers who have attended the mill while its been operating. The mill is permanently situated undercover so the variables associated with constantly moving it around don't apply. Can anyone out there help me with some solution to solve this problem?

[islandlogger]

What make is the Mill??

[bandmiller2]

Bob, the cold hard fact is that gearbox is not heavy enough for the job and the manufacturer is in denial.How does it fail Bob,does it overheat, bearings or gear damage??Frank C.

[Gary_C]

Ya, bandmiller2 is probably right. The only thing I know to do, other than re engineer it with a better gearbox is to try a high priced synthetic gear oil like a 75w-140. You can also get some EP (extreme pressure) additives from some oil suppliers that may help.

I sure hope the manufacturer is standing behind the gearbox.

[backwoods sawyer]

You should not be having that kind of problems with a 06 Peterson mill. Gearboxes normally do not go out very often unless they are in a bind. When installing a new gearbox is everything going together like it should, or is it being a real bear to install?

[submarinesailor]

Ditto what Gary said:

Ya, bandmiller2 is probably right. The only thing I know to do, other than re engineer it with a better gearbox is to try a high priced synthetic gear oil like a 75w-140. You can also get some EP (extreme pressure) additives from some oil suppliers that may help.

I sure hope the manufacturer is standing behind the gearbox.

I recommend you try this product:  http://www.amsoil.com/storefront/svo.aspx

Used it for 20+ years.  Never had a gear box failure.  Note - I'm not running a Peterson mill.

Bruce

[scsmith42]

Bob, I have a WPF, which I think uses the same gear box.  No problems in 3 years.

If I were troubleshooting the problem, I would check the belt tension and how hot the gearbox is becoming.  Thinking out loud.... if the mill operates almost continually, the problem could be that the gearbox is overheating.  An add-on oil cooler and recirculating pump may solve that problem.

I run the highest quality gear oil that I can - in my case it is a product made by Lubrication Engineers.  The Amsoil gear lube that Bruce recommended is also a very good product.

[Part_Timer]

Bob

I run an 8"ATS and have had it for several years without a gearbox problem.  Are you running synthetic oil in it?  How is it failing?  A little more information would be helpful.

[Jeff]

Bob, the cold hard fact is that gearbox is not heavy enough for the job and the manufacturer is in denial.

Um...  That's a pretty sudden rush to judgment dont you think Frank when you don't know the whole story? Like maybe this mill was bought second hand and out of warranty to begin with for example and have no knowledge whether it had some sort of previous damage contributing to the ongoing gearbox problem? And that we have never had another case history of this appear on the Forestry Forum in 9 years?

[Gary_C]

I have had an ASM saw mill for two years and in that time have had to replace the gear box 15 times.

Wow, 15 times in two years? I didn't take much note of that statement before but what has taken so long to ask for help? One or two times, maybe three but not fifteen times. Are you sure you are putting oil in it?  :

[Captain]

The one person I know of that had failures on that scale had a center unit that was not pivoting on the axis of the gearbox, belts loose in the vertical, overtight in the horizontal.

*Synthetic gear oil is a must.*

Is it a 1018 OR 1020 B&P gearbox?  Scratch that, I think all ASMs had the 1020.

Captain

[Farmer Bob]

In reply to all those who have made suggestions many thanks. Firstly I have been asking for help for the whole two years and have followed every recommendation by the maufacturer this is why I am now desperate for others help. The owner of the company actually came to Australia and helped set the mill up at one point and the gear box still failed. This mill was bought from an Agent with 120 hours on it and already one gear box replaced at 60 hours by the agent. I use the highest quality oil as recommended by the manufacturer of the mill and also the Italian manufacturers of the gear box itself. The gear box can be touched while in use so overheating is not a problem. The failure appears to occur around the pully bearing but several Engineers have verified the belts are not too tight. They have between 10mil and 20mil deflection. The bottom bearing above the blade is the other failure point. It chews out the bearing which then damages the housing. The gear box slips back into place perfectly and goes into the exact original position as this was marked by the agent when he had it.  Please . .  any more suggestions ???????

[Fla._Deadheader]

  Possibly aluminum gear box, and it "stretches" from hard use, and allows the bearing to get loose and destroy the race seat ?  Aluminum grows from heat ???  Look for a cast Iron gearbox, maybe ??  Do you know of any others having the gearbox problem ??

  From using my WPF in HARD wood, I see the abuse the gearbox takes. Mine needs a kit put in, and I believe the key seat in the blade-end shaft has wallowed out. The clutch does not disengage anymore, so, I need to tear it down before sawing again.

[scsmith42]

In reply to all those who have made suggestions many thanks. Firstly I have been asking for help for the whole two years and have followed every recommendation by the maufacturer this is why I am now desperate for others help. The owner of the company actually came to Australia and helped set the mill up at one point and the gear box still failed. This mill was bought from an Agent with 120 hours on it and already one gear box replaced at 60 hours by the agent. I use the highest quality oil as recommended by the manufacturer of the mill and also the Italian manufacturers of the gear box itself. The gear box can be touched while in use so overheating is not a problem. The failure appears to occur around the pully bearing but several Engineers have verified the belts are not too tight. They have between 10mil and 20mil deflection. The bottom bearing above the blade is the other failure point. It chews out the bearing which then damages the housing. The gear box slips back into place perfectly and goes into the exact original position as this was marked by the agent when he had it.  Please . .  any more suggestions ???????

It sounds like a lot of troubleshooting has already been performed, including most of the "easy items".

At this point, I think that I would look closely at the items associated with the gearbox that have NOT been replaced.  As a next step, I would have a high performance automotive machine shop check the static and dynamic balance on both the belt pulley (that attaches to the gear box) as well as the mandrel and blades.  They should have some type of universal mandrel that they can use to spin the parts upon an engine balancer.  If for some reason you had an extremely out of balance pulley, that could damage the bearings.

[DanG]

Farmer Bob, I'm pulling for you man, and welcome to the Forestry Forum.  I sure hope we can get this frustrating problem solved for you.

I have just one question...did those engineers that checked the belts check them in both planes, as Captain suggested?  That seems to be the only historical anecdote known.  If they didn't, I would check that at first opportunity.

Also, the ASM can keep the blade in the wood more than any other sawmill I can think of.  Could it be that you're just pushing it too hard?  After all, it is designed to be a portable mill, and is lightly built because of that. ??? :P

[Firebass]

This isn't the first ASM gearbox problem thats been solved here.  I'd listen to Captains Diagnosis first.  Here is why:...Because if the pivot axis is off then its like a giant CAM that tightens the belts when you rotate the blade then and side load of the gear box is stressed beyond its capacity.   If thats the case I'm sure the factory will stand behind it. to check this you could mount a dial indicator so it is reading the pulley with the belts off.  Rotate the carraige, I would think it should be within .015 Inchs maybe a little more.  But if its off .125" or so I think thats your problem.

Firebass

[LOGDOG]

Farmer Bob,

   Hate to hear that you're having problems like this. I've been there myself when it comes to equipment. Mentally exhausting ... the problem solving process. If you look at my gallery and posts, you'll see that I had an ASM. I sold it a couple years ago. I never had a problem with the gear box but I will say this; Peterson sent me an extra gear box without me asking them to - on their own dime. I had discussed possibly increasing the horsepower and if memory serves me right, there was concern on their end as to whether the gearbox I had would withstand the increased load. I neither increased the horsepower nor installed the other gearbox. I will say this though - I babied that ASM on the feed rate. The horsepower was light and if I pushed it much at all in a cut over 6" deep she'd really bog down. So I made it my practice to literally watch the RPM's and keep them high. DanG introduced a good question, "Are you pushing it too hard?". (Not saying you are.) Just rule it out. That machine is built too light for what we as the individuals who bought them tended to want to do with them. Don't get me wrong, there were days we made some serious sawdust in small dimension lumber that produced little drag.

   What concerns me is that the gearbox had already been replaced at 120 hours by the Peterson Rep. We don't have the advantage of knowing how he sawed or what may have lead to the initial break down.

   Have you altered your mill in any way from original factory specs?

   You can search my posts and in their you'll see me mention a problem I had with the setworks on my ASM. I can't tell you how many hours and phone calls I spent with Peterson trying to solve the problem. Over and over I would perform the things that were supposed to help troubleshoot the problem and diagnose the "known causes" of the symptoms I was experiencing. In the end it took two extra sets of eyes helping me spot the problem. It ended up being a bent arbor on the little electric motor that rotates the sprocket that moves the head left to right. (You likely know what I'm talking about.) The thing about it was, that arbor was completely out of sight from most points of view, it was completely out of the travel path of anything - you could barely get to it even when you wanted to let alone accidentally to bend it. That was what lead me to believe that the arbor had been bent at the factory. Perhaps the motor had been dropped on the arbor end or something.

   My point in telling you this is that sometimes - especially when we seem to have tried everything else by the book and according to the manufacturer, you have to be looking at the other things that contribute to the motion leading up to the mechanism that is failing. In my case it was an "unknown / previously unexperienced circumstance" that was causing my sypmtoms. It was unique to my mill and the journey it and it's parts had been through. Personally I don't think too much emphasis should be placed on the lubricant at this point. The best lubricant in the most misaligned mechanism will not prevent failure.

   Have you paid for the 15 gearboxes out of pocket or are Petersons picking up the tab on that? If Peterson is picking it up, they'd likely be money ahead to swap out your center unit, take your motor and mount it to the new center unit with new gearbox etc. and hope for the best. If you're paying for it then consider what you've spent thus far on actual parts and labor, downtime and frustration and whether or not you want the trend to possibly continue. Sometimes there is justification for scrapping part of an assembly and moving forward with new.

   I would be very, VERY curious what would happen if you took your center unit off after the gearbox has failed, crated it up and sent it to NZ where the factory could replace the gearbox to spec, drop it on a high / low track frame there at the factory and put one of their men on it sawing fulltime. How soon would failure occur? Or would it? There's only one way to know. Are you in Australia? NZ isn't all that far to ship it from there. Just a thought. It does need to be fixed - regardless of who's on the hook for the cost. You'll either need to fix it so that you can put it to work or you'll get to the point where you're frustrated and tired of dealing with it and need to fix it so that it is suitable for sale and you can sell it with a good conscience and recover some of your investment.

   If indeed the gearbox failed within the first 120 hours while in the Peterson agents care, I'm inclined to think that it is a mechanical misalignment or mismanufacturing of your assembly that is unique to your mill and began from inception. To know what that is would require measuring the specs on your assembly vs. the blueprinted specs to make sure that everything is aligned properly.  Focus on the mechanisms that contribute to the motion/ function of the plagued mechanism from beginning to end.

You can figure this out.  ;) Now I'm curious as to what it is. I'll check back on your progress.

Keep your chin up.

LOGDOG

[LOGDOG]

Adding on to what Firebass said, when you rotate the head ...raise your carriage height, and watch it from below as it rotates(with saw not running). Have someone else activate the switch for you on your command. If you're doing the activating you're not getting to see the parts in motion.

LOGDOG

[ErikC]

  Have the gearboxes been outright replacements?Or rebuilt with your old shaft and arbor? If rebuilt there may be a problem with that shaft wallowing out the bearings. It's probably not bent if the saw is cutting fine, but a little out of round or something. Good luck anyway.

[Gary_C]

The gear box can be touched while in use so overheating is not a problem.

It chews out the bearing which then damages the housing.

I just can't understand how this can happen. When a bearing or gear fails, overheating is always a factor. And if I generally understand what you meant by "chews out the bearing,"  that also cannot happen without a lot of heat being generated. There is just no way I know of to eat steel or wear out bearings without a lot of heat being generated.

Personally I don't think too much emphasis should be placed on the lubricant at this point.

LOGDOG, that was a very excellent post. However I must take issue with your assesment of the importance of the lubricant. All bearing and gear failures are a result of lubricant failure or stated another way, the inability of the lubricant to maintain a film separating two rolling or sliding metal components. Yes, the cause of the lubricant breakdown can be the loads exerted by misalignment or overloads, but lubricant failure is the end result that will cause metal to metal contact and overheating of the components. The only other cause is material failures that again will result in metal to metal contact or the inability of the lubricant film to separate the two components.

So in any gearbox failure, the lubricant is the first place to look. I personally have seen where undersized gearboxes have been made to carry the higher loads by the addition of some EP (extreme pressure) additives to the gear oil.

So in this situation, you should take a very hard look at the gear oil you are using. I know those synthetic gear oils are expensive, but they are still cheaper than failures. If a different and better gear oil doesn't help, the next thing to look at would be quality of the bearings in the gearbox.

[LOGDOG]

Morning Gary,

   I tend to think a bit differently. The saying, "an ounce of prevention is worth a pound of cure" is usually true in life. In my mind, you begin with good design, good components - sized appropriately for the job, and proper alignment and you will have less heat automatically, and certainly less failure.(At least in the bearing environment.) To me, lubricant (while necessary as a component) is the "pound of cure" sometimes meant to solve the heat issue that actually stems from poor design, poor components, misalignment, or mis-use/abuse of the mechanism for a task that is larger than it was designed for.

   The notion that this gearbox issue began so early in the life of this mill - while it likely still had the factorys choice of lubricants still in it leads me to believe that something is misaligned. One step further, because most mills stay fairly well aligned for a good while after being manufactured and sold, would look at whether something is mismanufactured - out of spec perhaps.

   When you compare my experience with the ASM vs. Farmer Bob's I would guess that I maybe had a smaller gearbox since mine was an earlier mill and they later changed the gearbox. Yet I never had a problem with it. I never ran super expensive lubricants in it. Just did my best to keep it aligned and respect the machines limits.

   Just talking through scenario's in the hopes of narrowing this down for Farmer Bob. Always enjoy your posts Gary_C. 


LOGDOG

[Gary_C]

    In my mind, you begin with good design, good components - sized appropriately for the job, and proper alignment and you will have less heat automatically, and certainly less failure.(At least in the bearing environment.)

That is certainly true. But the reality of good design is there are always tradeoffs. Size and space limitations as well as weight limits force even good designs into compromises that will cause overheating and failures under some, but not all circumstances. When a piece of equipment has to fly, move, or be lifted by hand it does limit a designers options.

The other major uncertainty in any design like this is the actual loading on the gearbox. It makes a big difference as to what kind of wood you are cutting and the duty cycle. A machine that is worked for an hour and then is down for a time may not see any problems with gearboxes while a machine that works steady for four hours may have repeated gearbox failures.

So I am not saying to ignore the alignment issues as they are controllable to some extent. I am just saying that the easiest way to overcome some of those overloading and alignment issues is to use a better lubricant.

[Firebass]

There are ways to design equipment to be reliable around the limits of space and wieght.  If the bearings are giving out before they're life it means they are exceeding they're dynamic load range.  Synthetic Oil will make a bearing last longer but its my opinion that the real problem is overloading of the bearing in the first place.   And that a gearbox should last a many years if designed correctly.  Think about it synthetic oil is a fairly recent invention and it really just makes it so engineers can cut corners on iffy or close to the limit design criteria.   
I have a example that might bring light.   I have a cheap China piece of Crap metal bandsaw that I was having to replace the gearbox in it once every 3 or 4 months.   I am brutal to it,  6 hours a day normally,  using a 4 tooth per inch blade cutting 4140 steel.  But about 2 years ago I decided that since it was under engineered for the heavy use I was giving it I would double up the roller bearing that was giving out.  This was easy since all I had to do was bore out the housing to fit 2 bearings instead of 1.   Since that fix I never have had a breakdown.  I expect I never will. 
My point is that maybe I could of got away with using "Synth Oil" but now its designed right and its not needed.
Maybe Someone needs to design a kit that can be bolted on to the gearbox to add a heavier bearing or a double row bearing.   

Making my Swingmill I solved this problem by designing my saw arbor (Shaft) completely separate from the gear box to take the dynamic side load off the gearbox.  The bearing that hold the saw blade and shaft  are  huge 1 15/16".  Yes it over kill but I never have to worry if it can take Industrial use.  As for the gearbox:  It sees no side load other than the belts that drive it and the blade is totally.  Its a standard 90 degree gearbox and a new one is only a few hundred dollars should I ever need one.   Not sure if this really helps but its good reading... ;)

Firebass.

[Gary_C]

There are ways to design equipment to be reliable around the limits of space and wieght.  If the bearings are giving out before they're life it means they are exceeding they're dynamic load range. 

In an ideal world that's true. But many times it is difficult to know exactly all the loads and stresses that will be put on a piece of equipment after it is built. And then there are manufacturing tolerances, assembly errors, and operator errors to consider.

I can tell a story too. There was a young machine designer that just finished designing a new machine and his supervisor looked at the drawing and said "that's nice, but it doesn't look strong enough, beef it up a little." The designer protested that he had taken every possible load into account and it was plenty strong, but the supervisor insisted and he was right. What the designer did not take into account was the possiblity that the operator would drop something into the machine and then get a four foot pipe wrench to unjam the machine. By the time he got the something out, everything would be twisted out of alignment and the machine would never be the same again.

And then sometimes costs can get in the way. It's one thing when you are making just one and another when you are going into production with many machines.

And other times if you are designing portable machines or airplanes the old saying "it has to fly" causes problems.

Before there was synthetic gear oils there were EP additives and before that there was Pennsylvannia crude. Those were all tricks to extend the life of gearboxes.  ;D

   Not sure if this really helps but its good reading... ;)

Sure hope so.  :D :D

[bandmiller2]

I may have shot from the hip with my origional statement about the gearbox not being heavy enough,I didn't realize it was a Peterson product,and they would not use a box that wouldn't do the job.Somehow I feel  we don't know all the facts,possibly a bad run of boxes from the manuf. or more likley the mentioned alignment problem.Really after two years of problems and many replaced boxes Bob should have been given a new or rebuilt mill and an autopsy done on the old one at the factory.Frank C.