Measuring Chain Sprockets to Find matching Chain Size

I have one of the old cast iron differential style chain hoists made by "D. Round & Sons Makers - Cleveland O. U.S.A." that had belonged to my grandfather. It's old but doesn't appear to be very worn so I'd like to put it back to light duty work (sentiment and all). At some point someone cut the chain off of it and I don't have a sample of what it had.


The differential sprockets have cast grooves and ledges on them for the chain to lock into, but they are not mirror representations of the chain. The dimensions I measured ended up being a non-existent size of chain, so I went for something we had on the rack and it seemed to fit ok and worked with no load.... until it got under a slight load the chain would slip in the sprockets, so obviously it's not the right size chain.

Before I start buying random chains, is there any way to measure a link chain sprocket to determine what size it takes?

My research turns up lots of stuff for roller chain, but nothing on link chain. I did find that the company is still in business making industrial lifts and hoists, so I shot them an email, but I imagine this is small potatoes for them.
Custom Engineered Lifting and Material Handling Products

I did find a picture of another of the same hoist, so worst case I can take the calipers to the computer screen and do some math.....

McMaster Carr catalog (#111) has a page Welded Chain - for lifting that lists dimensions of links. Covers Grade 120, 100, 80 and 60

Not that there is likely to be a perfect match for something OLD

Search under anchor chain, windlass, gypsy. There's some pretty old stuff out there for boats, even before 1900. Herreshoff did all his own castings, the drawings are in a museum back east, lots of adoring acolytes.

These days, the size of the chain is determined by the diameter of the wire it's made from, and there's several standard varieties, but I don't know about really old stuff. Mine was 1937, pretty new

johnoder said:

McMaster Carr catalog (#111) has a page Welded Chain - for lifting that lists dimensions of links. Covers Grade 120, 100, 80 and 60

Not that here is likely to be a perfect match for something OLD

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McMaster will likely be where I order it from. The blank I need to fill is what chain fits the sprocket so that it doesn't slip and locks into the grooves.

I found out that current chain hoists use non standard chain, and each maker seems to have a proprietary spec. Here's an example - Hoist Load Chain | Replacement Chain for Hoists
Those hoists used to be plentiful, and they are cheap when I see them, maybe you could watch your local craigslist or facebook marketplace and find a complete unit to take the chain from cheaper than new chain?

Circling back to this project, I THINK I have it figured out.

I held my calipers up to the computer screen () of the image I found in the first post, did some math and guessing, and came up with a 7/32 trade size chain. We also had a couple lengths of 1/4" and 5/16" trade size chains that wouldn't go through the sprockets without jamming, so if 7/32" doesn't do it, It's most likely custom or obsolete. I Bought a 25' length of 7/32" from McMaster (lifting grade), and it looks too small for the sprockets, but it actually lines up with all the indentations very well. It's slightly larger than the first chain I tried that would slip under load. I threaded it through the sprockets being careful to avoid any twists, cut and welded a joining link, and am about to load test it....

A modern chain to fit that hoist will likely be sold as "Not For Lifting".

Geared chain hoists are cheap enough that it hardly worth fixing up a differential hoist.

Illinoyance said:

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Geared chain hoists are cheap enough that it hardly worth fixing up a differential hoist.

Click to expand...

Asian import ones are cheap, but better quality hoists can get pricey really quick. This one's been in the family for awhile too, so I'm willing to put some time towards it. Sentiment's a dangerous thing.

So... the hoist is still slipping. The links grab into the sprockets grooves until it gets under a load and they start to slip. If I keep running the chain, it will lift slack out of the load and then hover there.

So I'm thinking either 1: the actual chain is custom or obsolete. It's almost like I need 1/4" trade chain wire that's made to the 7/32" trade link dimensions. The 7/32" fits really well and it's the only size that will thread through the sprockets without jamming, but it's like the links aren't heavy enough to stay in their grooves. Or 2: the sprocket groves are worn. It's likely but they don't look like it to my untrained eye. I don't see any steps or other typical signs of material wearing away.

So, I'm going to put this back in the box for now. Some solution will turn up someday. Especially if I throw it out. That's when the correct chain will surface.

Change the chain, and the sprocket, if pressed then you can just cut the core out a reweld to the old hub, assuming it’s not the lifting chain and it’s the pull chain, plus count the links, odd number shows a twisted chain, even is straight
Mark

Yes, hoists tend to use proprietary non-standard chain
I have an old hoist with separate hand-chain and load-chain. I hung it from a tall gantry and the hand-chain was too short, so I needed to add some. Non-standard. I found a chain with correc wire size but lnks were just a little too short........so I stretched it until it fit. Probably a really bad idea for the load-chain, and of course the hand-chain and the load-chain are the same chain on a differential hoist.