Method to measure drive chain wear.... What do you think?

[tjacobson01]

Folks, I have a 742B with 1400 hours. Since I had the front chain case cover off while changing chain case oil (under the brake pedal), I wanted to evaluate the condition of the drive chains. In searching this forum, a number of Bobcat manuals, and asking the dealer, I could find no empirical method to check wear. People talked about amount of sag, about chains touching the top or bottom of the case, rotational slop, etc. Nothing I felt that was reproducible or empirical. I surfed a bit, and found that chain manufacturers, such as Diamond (used in my 742B), have a simple tool to check chain wear. It is basically as special ruler you put along the pins of a chain under tension, to show if the chain is under the 3% wear limit they recommend. The end of the Diamond catalog shows how to do this, and what it s/b for various chain gauges. See the catalog: http://www.diamondchain.com/catalogs/diamond-chain-product-guide/#/22/ Or just Google the topic of "chain wear gauge". I simply made this tool out of a strip of sheet metal (soft aluminum flashing) putting a small ear on the end of it to catch the far edge of the starting pin 10 - 12 inches into the depths of the chain case, and being very carful to get it very precise using my digital caliper and a sharp knife to mark the aluminum. For No. 80 chain as used in my 742B it is easy, since the pitch is 1.00 inches, pin-to-pin. I marked the ruler at 7,8,9,10,11,12 and 13 inches pin-to-pin centers, and also put marks at the allowable wear limit of 1.03 over each, plus adding 1/2 a pin diameter for the starting ear. To put tension on the chain I found a simple method is put the end of the handle of a plastic covered 6" adjustable wrench under the first link engaging the large wheel sprocket and simply rotating the wrench, which raises the chain up into a straight line, and seems to put quite a bit of tension on the chain (needed to get an accurate wear measurement). I will post some pictures, when I figure out how to post pictures to this forum. I think sprocket wear is probably a negligible component of overall chain case wear, and condition of the sprocket teeth s/b simply inspected visually. Let me know if folks believe this is a meaningful way to measure chain wear, and if the 3% limit recommended by Diamond is good, or should we use a lower wear limit? I would be interested if some one has a badly worn chain that they had to replace, and could validate that this method shows this wear, and the need to replace it. Thomas Jacobson

 

[antfarmer2]

I just replaced mine on a 743 with over 4000 on it still good but I replaced them any ways because I put all new bearings and seals in.......just pick up the cat and grab the tire turn it back and forth should have a inch to inch and a half of play

 

[antfarmer2]

I just replaced mine on a 743 with over 4000 on it still good but I replaced them any ways because I put all new bearings and seals in.......just pick up the cat and grab the tire turn it back and forth should have a inch to inch and a half of play

They take 80 HD chains and count the links do not mesure one box will do the front and back on one side with a few links left over........there is a new guide out I put in much better will stop the wear you see on top of the reduction box

 

[tjacobson01]

Here are some pictures of the method, see album: http://www.skidsteerforum.com/DesktopDefault.aspx?tabid=52&gallerypage=1&currentitem=0&path=DriveChainMeasure Still wondering how I include them in the text of the post.... no help that I can find. Oh well. T.

 

[antfarmer2]

Here are some pictures of the method, see album: http://www.skidsteerforum.com/DesktopDefault.aspx?tabid=52&gallerypage=1&currentitem=0&path=DriveChainMeasure Still wondering how I include them in the text of the post.... no help that I can find. Oh well. T.

Put them in photobucket then link the image..........

 

[Tazza]

Put them in photobucket then link the image..........

Personally i wouldn't worry unless the chain was slapping around.
Some 743 machines have a plastic guide, others a metal one. The metal one is noiser (obviously).
With such low hours, i would think they would be in good shape too. If they are rusty, yes, time to change them out.

 

[tjacobson01]

Folks, I wrote this more trying to figure out the right way to measure wear, not so much my own machine (which is in great shape I think). I am not very happy with the "jack up the machine and rotate the wheels" sort of thing, as that is hard to quantify. Wanted to see if there was a more reproducible and empirical method..... Still have not figured out how to include pictures, so just go to the media/photos section of this site and look at the pictures I uploaded called DriveChainMeasure... gives an idea of the method, if anyone is interested. T.

 

[antfarmer2]

Folks, I wrote this more trying to figure out the right way to measure wear, not so much my own machine (which is in great shape I think). I am not very happy with the "jack up the machine and rotate the wheels" sort of thing, as that is hard to quantify. Wanted to see if there was a more reproducible and empirical method..... Still have not figured out how to include pictures, so just go to the media/photos section of this site and look at the pictures I uploaded called DriveChainMeasure... gives an idea of the method, if anyone is interested. T.

I guess you could get your mic out and compare all the links with the factory specs

 

[Bobcatdan]

I guess you could get your mic out and compare all the links with the factory specs

I always went by if there was enough sag to touch the top of chaincase they're too loose. Scientific enough for me, it isn't rocket surgery.

 

[Tazza]

I always went by if there was enough sag to touch the top of chaincase they're too loose. Scientific enough for me, it isn't rocket surgery.

I understand what you mean.
I think the specs for skid steers show that a set amount of wheel play is acceptable for that application. I don't know what the figure would be when measured.
There are gauges to measure the link distance so you can tell if there is wear or stretch of the links.

 

[7LBSSMALLIE]

there plastic chain measure guide put out by toyotata forklift is an actual tool to measure chains. basicly a go or no go device. it will measure stretch between pitch. a helpful tool whe showing customers as to why chains need rplaced.. GREAT.. old school grab the can if you can slap covers with deflection it time to replace also of note if you need proof you did need to replace chain . lay it flat on ground if it s bad you can make an s curve with it . its done. new chains will make about a quarter of a C