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Cast Iron Pulley Arm - Temporary Fix
2

Cast Iron Pulley Arm - Temporary Fix

Cast Iron Pulley Arm - Temporary Fix

(OP)
Hi All

We have a pulley arm crack as attached. The pulley is made of cast iron and rotation speed is around 257 RPM

considering this is cast iron and needs special welding procedure, we are thinking of applying Loctite or belzona epoxy glue as temporary fix till we get new one.

Interested to listen from you if this is an acceptable practice or not

RE: Cast Iron Pulley Arm - Temporary Fix

Does anyone get hurt when it fails? Does it damage other parts?
If not then try some things.
From the looks of that it is a poor design, very little radius.
Adhesive may work but you will likely need to make some braces out of steel and glue those in place also.
This is the sort of thing that I would mock up in cardboard to size and fit correct and then make the steel ones.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: Cast Iron Pulley Arm - Temporary Fix

Neither of those materials is strong enough to matter; you also won't be able to clean the crack enough if they were strong enough in order to get a decent bond. Welding will be problematic as the thermal stresses from uneven heating and cooling will likely break the pulley elsewhere.

Get a new one.

RE: Cast Iron Pulley Arm - Temporary Fix

I agree it is poorly designed product. I would suggest bracing the cracked arm to the main rim using bolts and nuts.

Welding or using a Loctite is not helpful.

RE: Cast Iron Pulley Arm - Temporary Fix

2
This is a good candidate for a brazed repair using silicon bronze filler. Grind the spoke completely through and build back up with bronze.

RE: Cast Iron Pulley Arm - Temporary Fix

what "broke" it ?
Impact or one major overload?
Second shift "maintenance" attempt ?
Old age ?

I'd want to see the rest of the part before contemplating a repair.
Might be simple, might not.

RE: Cast Iron Pulley Arm - Temporary Fix

It appears to be a straight spoke of a one piece cast iron pulley. These have been notorious for cracking for the last 200 years. There are a number of casting process factors that have to be done just right in order to prevent cracking. Curving the spokes is very helpful. But that is a design issue.

RE: Cast Iron Pulley Arm - Temporary Fix

(OP)
Thank you all for your helpful comments. Will get new one. For the time being, it seems we will try the suggested brazing repair with silicon braze filler

EdStainless (Materials)8 Dec 21 20:00
Does anyone get hurt when it fails? NO
Does it damage other parts? Don't think so. Also speed is very low around 257 RPM


Tmoose (Mechanical)8 Dec 21 22:29
what "broke" it ?
Impact or one major overload?
Second shift "maintenance" attempt ?
Old age ?
Not sure. could be old age + poor design as others highlighted above. The pulley is in service for 12 years now


RE: Cast Iron Pulley Arm - Temporary Fix

Tbe silicon bronze repair will be a permanent fix. There should be no need to replace with new if the repair is successful.

Brazing is a craftsman's skill so you'll need to find someone that knows how to do it.

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