Author Topic: Idler gear failures  (Read 31916 times)

diesel guy

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Idler gear failures
« on: November 07, 2006, 04:48:08 AM »

I have 4 Power Solutions (JKSON) engines (3-6/1’s and 1-14/1) and would like to know if there is anyone that had an idler gear failure in these models and make?

Can the people that had failures write in on the make, model and hours operated before the failure occurred?

I’m also interested in the GM-90 engines.

Thank you for you input,
Diesel Guy


xyzer

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Re: Idler gear failures
« Reply #1 on: November 07, 2006, 02:40:13 PM »
DG,
I have witnessed a failure on a P/S 10/1. the engine had 1500'ish hours running at 600'ish rpm 24/7. This failure was a wear issue not a catastrophic type failure. One side of the (brass/bronze) gear was beautiful (the pressure side driven by the crank gear), and the other side (pressure side that drives the cam) had wear issues. I don't know what the cam/idler backlash was of this engine is. After seeing this I checked out my dissembled 6/1 P/S and checked the backlash between the idler and the cam gear.  :o It had .023" of backlash! I machined an offset test pin and found it takes 1.3 x backlash=offset (ballpark). A .025" offset brought the backlash down to .007"...much better! I will wait for the return of my crank so I can check the backlash between the crank and the idler. Then I will be able to adjust both at the same time. It is much more difficult to check the backlash between the cam and the idler on an assembled engine. The crank/idler backlash is easy. I have come to the conclusion that there is a position error that can only be corrected by adjusting the idler shaft location. An offset bolt will be my fix.


The idler bearing area will be oversize to allow for the offset required. A larger head will allow me to have somthing to hold onto to turn the needed offset. The oil grove will be cut after I know where the top of the bolt is. 

DG What kind of issues are you seeing?   
« Last Edit: November 20, 2006, 06:25:49 AM by xyzer »
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Eco Diesel

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Re: Idler gear failures
« Reply #2 on: November 08, 2006, 01:35:05 AM »
If bronze was the choice material to use for the idler gear I think the original Lister CS engines would have used it. As Guy basicly says he couldn't see any way to engineer it to be more reliable. The old saying -There is no replacement for diplacement    (should have had added)   and proper metalurgy. Those bronze gears will need to be replaced many times with engines puting in long hours and will no doubt one day be at best described as sacraficial. If there was a failure of the idler gear teeth the bronze gear, it wouldl be like chewing on fresh raisin bran cerial verses steel idler gear fragments being like that of chewing on 10 year old raisin bran cerial. somethings gotta give. (usualy a tooth) I however, see no reason why this idler gear should ever fail if made from a good carbon steel that is heatreated properly. I mentioned it here once before that I have seen bronze worm drives in small bandsaws well submerged in gear oil that wear right out with no where near the hours or loads that these idler gears are expected to see. A high quality carbon steel casting with proper heat treatment is the only proper answer. Sorry I have no data to offer. Just thought it needed to be said. And as I never want to be accused of being a party pooper I need to provide a solution. What we maybe need to do is have a company like standard gear in Saskatoon make some serious idlers as replacements. I will bet they would last. If we had a hundred or so made they would be reasonably priced. What do you think?

diesel guy

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Re: Idler gear failures
« Reply #3 on: November 08, 2006, 02:03:43 AM »
Xyzer,

Your findings are very interesting. My units are still new and I’m putting on the finishing touches on them before completion. I have been exceptionally busy with one of my patents lately (Tractor Hybrid Propulsion System) and these gensets had to be put aside for longer than anticipated. I have an Isuzu LB1 with an oversize 10 KW generator head with dual 5548 inverters operational for now.   

I spoke to George last year and he mentioned using a power steering pump for an oil pump. With this information, I was thinking on mounting the steering pump and having two oil lines pumping oil directly onto the pressure sides of both the cam gear and the crank gear.

This would provide the maximum protection to the gear faces and I will be using 40 weight oil for a cushion affect as well. I purchased 6 bronze gears from George and will be installing them once the engines are broken in. 

I am going to tap a hole at the oil “full” level. This will be the return feed line to a auxiliary oil tank (10 gallon minimum), then through a dual filter system then the steering pump to the two oil lines. It will be installed below the engine and the inlet and outlet will be at the bottom of the tank.

This layout would enable the engine to maintain a full crankcase of oil without the need to shutdown and check level. Once stopped, oil can be added to the auxiliary oil tank, 2 or three gallons if needed without loss of lubrication issues. My gensets are designed for 24/7 operation only with no assistance from the inverters.

If you could, I would like an update on your offset bolt design.

Thanks for your input,
Diesel Guy

diesel guy

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Re: Idler gear failures
« Reply #4 on: November 08, 2006, 02:10:06 AM »
Eco Diesel

Thanks for reply as well, and if you can get those heat treated steel gears I’ll take 6 of them. Please keep me informed.

Diesel Guy

Doug

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Re: Idler gear failures
« Reply #5 on: November 08, 2006, 03:22:37 AM »
Back to the idler gear are we?

I had a thought....

Never seen or heard tell of them but the KOEL KS6 has a 1 year factory warrenty, so a KOEL gear should last at least a year. I wonder where a fellow could order KOEL EOM spares and see just how good they are and if they will solve some of these problems

Doug

xyzer

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Re: Idler gear failures
« Reply #6 on: November 08, 2006, 03:49:52 AM »
I'll bet Mr. Listers cam idlers were cast iron, not heat treated steel. I could be wrong for sure! I have no more faith in a cast iron/ heat treated or whatever gear if it is set up improperly. The best gear in the world will not fix the excessive backlash. Get it hard enough and it will last forever! Only problem is the cam or crank gear will be lost in the process. I'll replace idlers any day! I just thought I would pass on what I found. It was an obvious error that the Indians had part in. Yours may be different for sure.
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JohnF13

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Re: Idler gear failures
« Reply #7 on: November 10, 2006, 02:17:50 PM »
I know from experience that the idler gears in "some" Indian makes are just plain crap.  The whole gear train in the engines has proved to be a weak point and until we can get the Indians up to par on the backlash issue, it might be advisable to have the easiest to replace gear made of a softer material.  After you have changed a cam gear or two anyone will understand that.  All of my engines have bronze idlers as standard and I suppose they could well be classified as "wear parts" to be replaced on a regular maintenance basis.  Having said that, after 2500 hours on a 6/1 and 2400 hours on a 20/2 I have not seen signficant wear on my idlers, so for the "occasional" user it is not going to be a significant issue.  Yes, there is some "gold dust" in the sump of one of my 20's indicating that the gear is wearing slightly, but as I am aware of it it is not  a problem.  Busted iron idlers most definitely are, and hardened ones will only serve to destroy other components such as the cam gear and the crank gear.  Personally, I'd rather not go there.

I think the main problem is that the hole for the idler gear is slightly off in some engines, causing backlash problems.  No aftermarket idler is going to solve that and a hardened one is merely going to ensure that other parts that are much more difficult to fix, break.
John F
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Quinnf

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Re: Idler gear failures
« Reply #8 on: November 10, 2006, 03:08:04 PM »
How 'bout replacing the camshaft drive gear train with roller chain and two sprockets?  There should be room for the required 2:1 reduction.  Getting the cam gear mounted governor assembly modded would be the only hard part.

Quinn
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xyzer

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Re: Idler gear failures
« Reply #9 on: November 10, 2006, 03:29:39 PM »
How 'bout replacing the camshaft drive gear train with roller chain and two sprockets?  There should be room for the required 2:1 reduction.  Getting the cam gear mounted governor assembly modded would be the only hard part.

Quinn
Quinn....I would love to try that someday. With all the other mods that seem to improve longetivity I put that one up there in the next winter catagory. I can see no reason why it couldn't be done. A chain tenioner could be mounted in the idler bolt hole. You would have to have someway to adjust the cam timing wouldn't you? Someway to loosen the sprocket on the cam so you could adjust the timing correctly. I am going to correct my idler/cam gear backlash and see how it does. I am convinced the bronze gears are fine if they have the correct backlash. Time will tell.....
Dave
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biobill

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Re: Idler gear failures
« Reply #10 on: November 11, 2006, 01:06:42 AM »
  I've got a "gear knock" in my 6/1 maybe someone could shed some light on. The idler gear normally runs away from the case (against the bolt shoulder) until the exhaust lobe overcenters at which point it slaps up against the case. Makes quite a bit of noise, like a rod knock. With a helical cut I could understand the load/unload side movement but with straight cuts???  Had it out today. Should have taken some measurements but didn't. Gear is sloppy on the shaft - normal? End play must be close to a mm.  Thought about shimming to reduce the endplay or, alternatively, cutting back the shoulder that butts against the case. Then decided I'd ask first. Anybody been there, done that? 
  xyzer, not sure if this is what you meant, but it's common practice to slot the holes in the cam sprocket where it bolts to the flange on the cam. This allows you to get a timing that's between teeth

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xyzer

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Re: Idler gear failures
« Reply #11 on: November 11, 2006, 02:17:26 AM »
  I've got a "gear knock" in my 6/1 maybe someone could shed some light on. The idler gear normally runs away from the case (against the bolt shoulder) until the exhaust lobe overcenters at which point it slaps up against the case. Makes quite a bit of noise, like a rod knock. With a helical cut I could understand the load/unload side movement but with straight cuts???  Had it out today. Should have taken some measurements but didn't. Gear is sloppy on the shaft - normal? End play must be close to a mm.  Thought about shimming to reduce the endplay or, alternatively, cutting back the shoulder that butts against the case. Then decided I'd ask first. Anybody been there, done that? 
  xyzer, not sure if this is what you meant, but it's common practice to slot the holes in the cam sprocket where it bolts to the flange on the cam. This allows you to get a timing that's between teeth

                                          Bill

Bill,
Yes I knew that on a gear....I was refering to QuinnF's suggestion of a chain drive but then you could do the same with it also.
 I have heard the knock you are refering to. Have you checked the backlash between the cam/idler?
Dave
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Geno

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Re: Idler gear failures
« Reply #12 on: November 11, 2006, 01:29:33 PM »
  I've got a "gear knock" in my 6/1 maybe someone could shed some light on. The idler gear normally runs away from the case (against the bolt shoulder) until the exhaust lobe overcenters at which point it slaps up against the case. Makes quite a bit of noise, like a rod knock. With a helical cut I could understand the load/unload side movement but with straight cuts???  Had it out today. Should have taken some measurements but didn't. Gear is sloppy on the shaft - normal? End play must be close to a mm.  Thought about shimming to reduce the endplay or, alternatively, cutting back the shoulder that butts against the case. Then decided I'd ask first. Anybody been there, done that? 
  xyzer, not sure if this is what you meant, but it's common practice to slot the holes in the cam sprocket where it bolts to the flange on the cam. This allows you to get a timing that's between teeth

                                          Bill


My gear fits the shaft well but does have some end play. Exact lash unknown but *seems* OK. If shimmed or sholder cut it would be more centered on the other gears as well. I think I ruled it out for some reason but can't remember why. Maybe I should rethink it. I also have something slapping a bit in there every other revolution under load. Maybe mine does the same thing, maybe its normal. I have only seen one other Roid.
Thanks, Geno

dave s

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Re: Idler gear failures
« Reply #13 on: November 11, 2006, 09:00:03 PM »
WHAT ARE THE ODDS. TODAY TORE DOWN PS 6-1 LOOKING FOR THAT KNOCK. THE ONLY THING I FOUND WAS THE IDLER GEAR HAD ABOUT 80 THOU FOR AFT CLEARANCE. WHEN I MOVED THE GEAR FORE AFT IT BANGED JUST LIKE WHEN THE ENGINE IS RUNNING. I GUESS CUT THE SHOULDER ON THE BOLT, OR A 60 THOU SHIM. ANYONE??

biobill

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Re: Idler gear failures
« Reply #14 on: November 11, 2006, 11:45:32 PM »
  A closer examination showed that the side to side movement is not limited to when the exhaust cam lobe overcenters but is also triggered by the intake and injector lobes though to a lesser degree. And, the gear tilts as it moves , probably due to excessive clearance on the shaft.
  Idler/crank backlash is a little more than I'm used to seeing but may very well be OK. More like a tranny gear than a cam drive gear.
  Idler/cam backlash is huge and like xyzer said, really tough to measure on an assembled engine.

  I'm liking the eccentric shaft fix more and more (being a bit eccentric myself). Suppose you could bore and offset bush the case..but not in my basement. Seems like with the shaft you could just tweak it til you find the sweet spot as long as you left sufficient idler/crank clearance. If the idler is center then the crank is 6:00 and the cam is something like 9:15. Favor the crank a bit and you could snug that up too. Any thoughts about how to lock bolt in position so it doesn't shift if you need to tighten the bearing holder/cover?
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