50L rotovap replacement worm gear set

I have a Chinese 50L rotovap. Model RE-5003. The evaporating flask no longer spins.
After taking apart the gear set I found out the worm wheel is made out of plastic and it has worn away.

Has anyone got the specs and made a replacement out of bronze?
Does anyone know someone who could make a replacement set?

I can get a replacement from the manufacture, but with chinese new year it will be 2 weeks before anyone can send one. I’m trying to figure out something quicker.

Thank you


If it’s worn evenly, copying it may not be possible.
If it simply has missing teeth, you might be able to find a company to build you one in a hurry.

That will cost you a bit…so try for an off-the-shelf solution instead.

The gear you’re looking at is likely metric, and probably not made explicitly for the rotovap.

Get yourself some callipers, then start here metric worm gears - Google Search


Maybe @Terry_Manager can find a suitable part

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Just curious how long/how much use did you have on your re-5003 before this happened?

I just got one myself and wondering if I should have a backup worm gear incase this happens with mine too.

I am manufacturer and we have been manufacturing re-5003 and it is manual lift; I could provide any part with u and just tell me which part u want, then I will quote to u


@Theterps post a pic

@Terry_Manager could you guys make a metal or bronze replacement gear?

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chances are that would just break something else…

often times, having a plastic gear strip rather than trashing something else (the glass or the motor in this case) can be seen as a feature, not a flaw.

…and great call on paging in our resident rotovap manufacturer!


I’ve been around several 20l & 50l rotovaps that were run hard 24/7 and haven’t seen this failure yet. @Theterps is also the first one I’ve seem bring it up here, and I’d posit there are tens of thousands of rotovap hours in this collective.

So I’m going to guess it’s not super common.


It wouldn’t be as simple as a swap in either. I’m sure the drive gears are plastic as well. You wouldn’t just swap in a single spur gear thats bronze mated to say a plastic worm gear.

I’d just buy a few replacements for the future and call it good. Like cyclo said the failure point moves from the gears to something far more expensive to replace.

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This is sooo awesome! Glad your a part of this community @Terry_Manager This is where having a direct chinese supplier with the capabilities to get replacement parts easily is awesome.

Imagine calling up any of the manufacturers that make or re brand rotos. I dont think it would be as easy to get this worm gear set as @Terry_Manager made it available…i could be wrong but this seems pretty cool.


I like to have spare parts on hand reguardless. May just order the ring and end cap set just to keep on the shelf, for those “in case shit happens” times.

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If I could get a replacement sent right away that would be great @Terry_Manager
Everyone I have talked to can’t ship anything for 2 weeks, due to the Chinese new year.

I just bought it. I used it for about 3 days. I had it max rpm and maybe too much weight in the flask.


I’ve spent a lot of time searching on line for someone who has a metal one in stock, but I haven’t had any luck.
The Bore diameter for the wheel is 70mm, this has been the hardest part to find

those 1k word substitutes really help define the problem.

I can see the attraction of a bronze replacement…

I agree with your diagnosis of likely cause.

given the way I see our 50L’s being pushed, I’m gonna locate some spares too.

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So we replace the gear with a bronze one, then figure out what breaks next. Replace that one with an upgraded part, move on. Repeat until the glass itself is now the weak point, replace all the glass with stainless components, and suddenly it would have been 5x cheaper to buy a german or swiss one in the first place.

This is why my plan for cheap chinese rotos for our facility is to have at least N+1, likely N+2 redundancy. Something like this shouldn’t cause more than an hour or two of downtime.


Hello Guys,

I have a couple Rotos and I just had one machine have the same problem that [Theterps] had. The company sent me a new gearbox but I cannot get the gear to make a full revolution.

I think i am lining up the worm and gear wrong… anyone have any input that my help me? Thanks!!!

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I don’t have the knowledge to help you but I’m sure if you include a picture or two it’d make it easier for someone who does to assist you

sry for delay.

now do you still want the replacement for rotovap?