gas powered concrete mixer

[38racing]

Anybody with experience with these. I have just the mixer and large pulley is gone. No engine but a have that gx200 clone waiting on new carb. I think I can make it work .It seems they normally use an engine with 6:1 gear reduction. Would it still be direct direct drive? ie to start engine drum has to turn. If I use a centrifugal clutch it makes it too expensive. I need about 200 rpm on the drum shaft to get 28 on the drum. I figure on regular drive gas engine. I figured on using chain drive. A 72 tooth gear (about 9" ) on the drum shaft (normally a 20" belt pulley) That will be driven from a jack shaft 12 tooth. input side of jackshaft is 36 tooth driven by a 12 tooth on the engine. My theory is it takes certain torque to turn drum. So 9" pulley instead of 20 means a larger force to get that torque. That's why I figure chain rather than belt. And in fact chain stuff will be cheaper than belt stuff as gears are cheaper than pulleys when welding to hubs.
edit- just looking at manual for a gas operated unit. Says to turn switch to on. When mixing poured turn switch to off. LOL I think they copied from electric unit manual.

[KE4AVB]

Looks like your getting a 18/1 gear reduction so the 3600 rpm will drop to 200 rpm at the drum shaft. Plenty room to slow down when needed that if you are planning throttle controlled engine that can idle.

[38racing]

i based it on 3450 is I end up using an old air compressor motor on it. just found out a second friend has a mixer if i need one but just can't resist the challenge of fixing this one.

[38racing]

well, you win some, lose some. I got all the chain and sprockets to make it work at right speed but in the end the drive shaft area of the mixer was too worn. I had hoped there was a replaceable bearing but that was not the case. Shaft play would make chain much tighter when in dump position. Leaving enough slack for that meant chain was too loose in mixing mode and that along with shaft movement would throw the chain. It's back where I got it at our church metal recycle bin.