We have a 47M Schwing and have a heck of a time with bad mixes. It seems like it always wants to jam at the top of the 3rd where it reduces to a 4.4" pipe. Has anyone replaced the jib with 5" or is their another solution. It is very frustrating.

long time ago i had the same problem with a coime i used to operate, my boss at the time replaced the 4.4" with 5" tubes and after two years the boom started to have cracks so i wouldn't recommand it.

Is it a straight reduction? How long is the reducer? Would a longer reducer make a difference? How about if the reduction were made in a reducing elbow? The different rates of velocity around the radius makes the reduction more efficient. Why didn't they go with 4.4 right from the deck? I know the pipe is more expensive and the wear rate is higher, but plugs are so damn inefficent and frustrating and potentially dangerous.

Some good information posted.We were having troubles as well,con forms was a great help.Had much the same issues when we converted the 52m's to 55m.

Pumpjocky was right on

It sounds more like an alignment issue. Try pulling the elbows off the third section and see if you have any pipes not lining up. I had a problem with a 61m were i couldn't get a prime past the 3rd and 4th sections. I opened it up and all the pipes had shifted leaving 1/8" lips all over the place. I had not had any isues before this all started. When we first got our 47m we had plugging at tip elbows due to alignment.

You could also check the inside messurements of the reducer and the pipe goin in to the reducer. There could be a ''lip'' there to.. If its a realy bad mix.. why not use 5 liters water and a quarter bag of slick pack...

I guess you are already very precise with the possition of the boom while priming? Last 2 sections as much as possible straight down... Or 1,2,3 up in an angle and 4 straight down.

That last one worked best for me on the 52m schwing since 1 and 2 are so short that it was hard to get 3 and 4 straight down.. (if you catch my drifting)

cut of 2 meter of the jib make it a m45 and you can go all 5"

Try just replacing the two 90's in the pass thru from 4" to 5" elbows it has worked pretty well for me on a couple trucks I think the reduction then the turn thru the pass thru screws it up and make sure ur reducer isn't on backwards.

Reducer backwards?? Is this a joke again?

Just a thought..I could also imagine you could get some left over concrete in the reducer when you suck a ball. The bal has to expand when it goes from 4'5'' to 5'' This take a tiny bit of time but if the ball goes quick... And accelerates because it gets less friction in the 5'' pipes it could just be it leaves some concrete behind there..

I don't know how long this reducer is but in a boom i'd vote for a 3m long reducer.. 

Actually the 4.4 is a weight issue to not overload the boom.  I know you can actually put the reducer on backwards and for some reason plug (yes the reducer can go on backwards)   also are you laying the boom flat out when sucking the ball back?  Thats what a lot of guys I know do and they don't seem to have many problems

Sucking back a ball folded up is an easy great way to clean out. Suck back as slow and easy as you wish. I do it all the time my pipes look like I water wash.

i know someone put the reducer on start of stage 4 to alleviate the problem but wouldn't recomend it and niether will schwing.when i cleaned my old one i blew out,then sucked back then put water in thru the kung fu and blew out again.only had 2 blockages in a year there putting it thru with water on 7 or 8.pipe allignment could be an issue hope ya get it sorted still pumping hard on the goldcoast aust.