Need a little input on a cement mixer rebuild

lostcause · Mar 13, 2012

This isn't a true built-it-yourself, but since every piece of it needs to be reworked to some extent, it's pretty much like building it from scratch. Last fall I dragged this battered cement mixer home - it was scheduled for a date with the scrapyard if I hadn't intervened:

For additional reference, the drum measures about 24 inches at the widest point, 18 inches at the opening, and 30 inches long.

The best I can tell it was always PTO powered, but I think it has been used as both towed and 3 point hitch. The axle it a retrofit, and the 7/8 bolts welded on for 3 point lift are obviously not original, so I have no clue how this started out life. I am going going to put it back to life as a 3 point hitch implement, but since it has been hacked apart and cobbled together, it's hard to tell exactly how it should be set up. I need help with the following things:

1. What is the height of the average mixer at the bottom of the drum, when set for mixing? In the following picture I have it tentatively set at what I think might be a good height. Assuming that the angle I have it set at is reasonable for mixing, would 33+ inches from the floor to the bottom of the drum be a good height to shovel into? For those of you with mixers, what is the height you have to shovel to? I need it to be as high as is reasonable so that when it dumps you can get a wheelbarrow under it.

2. What is an acceptable rotational speed for the drum on a mixer? I don't trust any of the pulley sizes to be correct, so I want to start with the drum speed and work backwards. What I know to start with is that I have an 81:8 ratio on the ring gear and a 1:1 ratio on the gearbox, so I have to size the pulleys to get the final speed from the PTO reduced. I'm thinking drum speed should be around 50 RPM? This question leads me to my final question - for now...

3. Is a tractor's PTO speed linear? What I mean is that my tractor is rated for 540 PTO RPM at 2600 engine RPM. Does this mean that at idle (800 RPM) the PTO speed would be about 166 RPM? I'm hoping I can run the tractor at about idle, since it shouldn't take too much effort to spin a mixer drum. I'm going to be using this with a John Deere 770 which is a 1.4 liter diesel with around 24 engine HP and 20 HP at the PTO. Do you think i can do this at idle, and will my PTO speed be what I think it will be?

Here's where it sits right now:

The sheet metal seam on the drum has been cut out and welded since it had been partially separated. The drum has been straightened and a new and heavier ring has been welded on to reinforce the opening.

The entire frame has been adjusted (bad welds and poor alignment corrected as well as possible). The vertical supports have been reinforced to limit flexing.

The yoke has been cut and welded up so that it matches the contour of the drum as opposed to being straight. The original yoke had long ears on it that had flexed and bent at some point. the contoured yoke has less free length to bend. The original also appeared to have been built in place. there was no way to take the unit apart without cutting it. There are now bolts holding the ears to the yoke to allow removal.

The next step is to figure the height I need for everything and then build skids and legs for the unit to rest on.

cmhyland · Mar 15, 2012

Looks like a great project. Do you have rear remotes on your tractor?

If you do I would look at converting to a hydraulic motor to run the drum. Also a dump circuit would be cool...

My thoughts are that when your using the mixer you could add mix and water without actually having to get on the tractor to engage the PTO... Also you can just bump it to move the drum when your adding materials or cleaning ...

FredH · Mar 15, 2012

Mine is not a 3 point / PTO model but electric but here are some measurements I took .

Using one of these :

Angle Finder w/ Dial Gauge

I had 40 degree's with the gauge on top the drum or 55 degree's inside the drum by the lip . Difference is due to the taper of drum .

From ground to bottom of lip in mix mode is 40" BUT mine could actually be a few inches higher , ( we actually put it on 4"x6" blocks when mixing ) , so when you dump it clears a standard contractor wheelbarrow . Even at 44" , it is still pretty easy to shovel into it . I mixed 2 yards by myself 2 years ago for a slab for a new lawn / storage building , sore yes , but not impossible for a 50 year old .

With a 3 point , I would think that you would be able to lower to mix then raise to dump so height could be whatever ??? Never seen a 3 point mixer up close or used one so I may be all wet there ? I would also think your tractor would be more than adequate for that at idle since mine runs on a 1 or 1.5 h.p. electric motor on 110 /120 volts . I think that 50 r.p.m. estimated drum speed is still to fast , Maybe 1/3 that ?? I will run a electrical cord out to mine in the morning and verify actual r.p.m.'s though .

Fred H.

Hooked_on_HP · Mar 15, 2012

I am not positive but I think what you have is a morter mixer. The fins inside the drum would be spiraled if it was for concrete. The fins in yours are straight. Depending what you are planning on doing with it it may work fine.
Bill

lostcause · Mar 16, 2012

FredH said:
I had 40 degree's with the gauge on top the drum or 55 degree's inside the drum by the lip . Difference is due to the taper of drum .

From ground to bottom of lip in mix mode is 40" BUT mine could actually be a few inches higher , ( we actually put it on 4"x6" blocks when mixing ) , so when you dump it clears a standard contractor wheelbarrow . Even at 44" , it is still pretty easy to shovel into it . I mixed 2 yards by myself 2 years ago for a slab for a new lawn / storage building , sore yes , but not impossible for a 50 year old .

With a 3 point , I would think that you would be able to lower to mix then raise to dump so height could be whatever ??? Never seen a 3 point mixer up close or used one so I may be all wet there ? I would also think your tractor would be more than adequate for that at idle since mine runs on a 1 or 1.5 h.p. electric motor on 110 /120 volts . I think that 50 r.p.m. estimated drum speed is still to fast , Maybe 1/3 that ?? I will run a electrical cord out to mine in the morning and verify actual r.p.m.'s though .

Fred H.

Thanks. I really appreciate you taking the time to get those measurements and numbers. I just don't have anything nearby to look at and take numbers from. This is proven by the fact that i just started messing with this about a week ago, and two friends have already mentioned they have summer projects planned that they would like to borrow it for. I don't use these very frequently, and It's hard to figure exactly how fast, how tall, and what angle it should be at. something as small as a difference between 25 and 50 RPM is the difference between a 3" and a 6" pulley.

Hooked_on_HP said:
I am not positive but I think what you have is a morter mixer. The fins inside the drum would be spiraled if it was for concrete. The fins in yours are straight. Depending what you are planning on doing with it it may work fine.
Bill

Yeah, for any small projects that I may need it for, any mixer is better than a plastic tub and a garden hoe. I've never troubled myself to learn the difference between a mixer for mortar and concrete, but I always assumed that any of these small mixers are generally mortar mixers.

rambler · Mar 16, 2012

I got a 3pt mixer, works well, I'm gonna be gone most of Friday starting early, but if I can remember I can look at the belt pullies. You run the tractor at idle, dad had 2 mixers that were pto driven, not 3pt, but you always run the mixer at idle, they spin slow. If you just use the same preportion of the pullies I have, should work out.

I never sat my mixer down on the ground to mix, kinda keep it 6 inches to a foot off the ground, so it dumps in a wheelbarrow nicely.

--->Paul

lostcause · Mar 16, 2012

cmhyland said:
Looks like a great project. Do you have rear remotes on your tractor?

If you do I would look at converting to a hydraulic motor to run the drum. Also a dump circuit would be cool...

My thoughts are that when your using the mixer you could add mix and water without actually having to get on the tractor to engage the PTO... Also you can just bump it to move the drum when your adding materials or cleaning ...

i do have rear remotes, but I'm going to be keeping this PTO powered. I already have everything needed to go with PTO, but with hydraulic powered I would need a hydraulic motor, hoses, and fittings.

My intent is that once on location I will use the tractor as a power source and nothing more. When using an electric or engine powered mixer you only fill it and dump it. If I were to have to keep going back to the tractor to use controls I think it would be somewhat counterproductive. Some have said height isn't important since I can raise and lower it with the 3 point hitch, but i think that once running you shouldn't touch the tractor's controls until you take a break.