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12 G BROKEN CHAINS

Bestblade

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61M07000 I’ve had this 12 G since 1986 . I work around 1000 hours a year. The last ten years I’ve probably Broke 4 chains always the rear driver.A couple of times you could see the master link was damaged.I’ve had to make a lot of repairs to the tandems .Has any one got fix for a high hours machines chains.If it was a dirt bike I’d put new sprockets on it.The chains have all been replaced.They seem to get damage when I’m on a slope.
 

Nige

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G..G..G..Granville.........!! Fetch your cloth.
Have you ever checked the chains for wear so they could possibly be replaced before failure.? See attachment.
There are updated parts for many grader chain master links but I don't see anything for a 12G.
What Part Numbers are you using to make repairs after a failure.?
Are the sprockets still original.? Damage to them might be a contributing factor to accelerated chain wear.
 

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Bestblade

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I put all new after market chains on last year 6G1633 this year I broke the right rear diver again and replace it with a Factory chain and it broke again.The mater link was sheared off . Thanks for looking into this Nige.
 

Nige

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I put all new after market chains on last year 6G1633 this year I broke the right rear driver again and replace it with a Factory chain and it broke again.The mater link was sheared off .
I think I'd be looking very closely at the condition of the sprockets.

What about checking the chains for wear.? If the machine only does about 1000 hours a year it could probably be an annual check.
If the chains are stretching an inspection should hopefully detect that in advance of a chain breakage, although it would do nothing to detect a master link failure. How many of the failures have been a broken master link.?

A bit oif a curve ball from left field but have you inspected for wear in the fibre bushes located in the pivot between the tandem and the final drive.?
If you have a ripper it's easy enough to jack up the machine using that and the moldboard. If not then you have to put a jack under the chassis. Watch for the tandems "falling down" as you raise up the machine. Wear in that bushing can affect the way the chains run big-style.
 

Bestblade

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The fibers have all been replaced the last time I was in it that side i had the housing 6G3283bored and a sleeve put in but all the sprockets are original and suspect.The chains have always hit the bottom of the case even after new chains were installed. I guess I wondered if any one had ever tried a half link.
When my chain broke I was knocking done a 200 + trucks a day . I caught it pulled the chain in about 15 minutes and was back to work but noticed that the right side was always pulling.so if I wasn’t locked up I only had one wheel drive.I’m guessing the right side does the most of the work.
 

Bestblade

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My mechanic said he’d look at it on Tuesday replace the chain and inspect the sprockets thank you
 

Nige

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The chains have always hit the bottom of the case even after new chains were installed.
That suggests worn sprockets to me. I don't know what anyone else thinks.
My mechanic said he’d look at it on Tuesday replace the chain and inspect the sprockets thank you
See if you can get some good photos of the sprocket teeth while he's in there replacing the chain.
 

pedrocar

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Seems funny ,chains dont strech to much ,but if your on slopes still shouldnt make any difference be checking the alignment of the sprockets , check for abnormal wear on tooth pattern,mine have done 20k no issues
 

56wrench

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Just a thought. Are you going from forward to reverse while on a slope? Going forward, the slack will be on the top of the front chain span and on the bottom of the rear chain span. The sag in the front span will keep the chain on the drive sprocket cluster when you change direction but because the rear chain is dragging on the bottom of the case, it may allow the chain to climb on the centre sprocket cluster if its loose enough when you change direction to reverse. It could also happen on the rear hub sprocket while going forward on a slope
 

Bestblade

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So I ordered 2 boxes of Diamond 160 H chains on EBay they come in ten foot chains and you cut to size. Last time I used cat part numbers and one seller backed out . So I only ended up replacing one chain.We accidentally switched masters the old master on the new chain broke at the pin were it showed wear .
The sprockets don’t show much wear even in the cup it’s minimal.Thanks for your interest
 

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56wrench

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Is that sprocket on one of the wheel drive hubs? What does the sprocket in the centre of the chaincase look like?
 

Nige

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If as the OP says a brand-new chain touches the bottom of the tandem housing when installed there HAS to be some major wear on the sprockets IMO.
Unfortunately although the photo of the sprocket tooth shows some wear it is not clear. A photo taken from the side would show the true extent of the wear.
 

digger doug

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Those pix show a fracture, and the pin is not worn down much.
Note also the broken side plate wear ?

I'm thinking pinched/de-railed climbing up the sprocket.
 

56wrench

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I think we need a picture of the centre drive sprocket in the middle of the chaincase. The teeth may show some interesting marks/wear.
 

Tyler d4c

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Could it be that one of the sprockets on that corner is made wrong as in wrong diameter thus putting excessive force on the chain. I suppose a well worn one one would lead to a similar problem
 

Vetech63

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Usually if the chain has ridden over the sprocket teeth there will be scarring on the chain or sprocket itself. Have you inspected the chain completely for this? I'm not sure you can get good enough pics of the sprocket unless they are removed. Pin fractures like that are usually caused by a shock load to the chain..............or weak material from the manufacturers build. I'm not seeing what I would expect from a chain walking over the sprocket teeth, but maybe its there somewhere.
 
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