converting a 3-pt concrete mixer from PTO to hydraulic drive

[jim_wilson]

You can calculate the RPM you are going to get, knowing your flow rate and the motor displacement. Or you can
just use the SurplusCnter motor app.

Pressure is not important for a hyd mixer, as it does not take much to turn the drum. However, it would be
great to have a drum spin at as little as 30RPM. 60RPM is plenty fast at the upper end. That rules out direct
drive, unless you get a gigantic motor. If your slowest speed is too fast, low-slump mud will just adhere to
the inside of the drum, without any mixing action. BTDT.

Because the power required to turn the drum is so low, you can run the tractor at barely over idle speed without
bogging then engine. This would give you about 1/3 of your rated flow, perhaps 2.2 GPM. Count the spocket teeth
and buy a drive sprocket that gives you the reduction ratio you want.

I was wondering about that. I looked up the specs on the Mixer 80 mixer though...... and it's claiming it's a 10-1 drive. Which, correct me if I'm wrong - but it means that even at max PTO speed of 540rpm- the most you're ever going to get out of that mixer is 54rpm - being direct driven by the PTO drive.

So.......... I would think that means that what I need to direct drive this thing with a hydraulic motor - is something whose max RPM is going to be in the ~ 540 range.

How about this one:

2.8 cu in CHAR-LYNN 101-1025 HYD MOTOR

1800 psi cont
2400 psi inter (puts it right in the range of my tractor)

Speed:
969 RPM cont.
1127 RPM int.
Flow:
12 GPM cont.
14 GPM int.

The B3200 is rated at 6.7 gpm according to tractordata.com

If the above motor does 969 rpm at 12 gpm - my calculations show that it should do ~ 524 rpm - at 6.5 gpm.

Seems like that puts me right in the sweet spot GPM / RPM wise.

The above motor only has a 650 in lbs continuous torque rating though - I'm wondering if that would be enough to spin the drum.

 

[SSdoxie]

I was wondering about that. I looked up the specs on the Mixer 80 mixer though...... and it's claiming it's a 10-1 drive. Which, correct me if I'm wrong - but it means that even at max PTO speed of 540rpm- the most you're ever going to get out of that mixer is 54rpm - being direct driven by the PTO drive.

So.......... I would think that means that what I need to direct drive this thing with a hydraulic motor - is something whose max RPM is going to be in the ~ 540 range.

How about this one:

2.8 cu in CHAR-LYNN 101-1025 HYD MOTOR

1800 psi cont
2400 psi inter (puts it right in the range of my tractor)

Speed:
969 RPM cont.
1127 RPM int.
Flow:
12 GPM cont.
14 GPM int.

The B3200 is rated at 6.7 gpm according to tractordata.com

If the above motor does 969 rpm at 12 gpm - my calculations show that it should do ~ 524 rpm - at 6.5 gpm.

Seems like that puts me right in the sweet spot GPM / RPM wise.

The above motor only has a 650 in lbs continuous torque rating though - I'm wondering if that would be enough to spin the drum.[/QUOTE]
If you have a 10:1 sprocket ratio and motor on the small sprocket, won't that multiple the torque at the drum the same ratio (X10 = 6500 in/lb. 542 ft/lb.)?

 

[dfkrug]

The above motor only has a 650 in lbs continuous torque rating
though - I'm wondering if that would be enough to spin the drum.

More than enough torque, as Dennis points out. Even at idle speed.

When you say direct-drive the mixer, you mean to direct-drive the drive sprocket, not the
drum.

Going back to page 2.... I landed a great deal on a 6.7 ci motor. You have some wiggle room
with respect to what motor you get because you can easily change the drive sprocket. It is
easier to replace the drive sprocket, vs. coupling your motor shaft to the existing drive sprocket
shaft. If you do the latter, you will also have to build a support framework for the motor.

 

[jim_wilson]

I was wondering about that. I looked up the specs on the Mixer 80 mixer though...... and it's claiming it's a 10-1 drive. Which, correct me if I'm wrong - but it means that even at max PTO speed of 540rpm- the most you're ever going to get out of that mixer is 54rpm - being direct driven by the PTO drive.

So.......... I would think that means that what I need to direct drive this thing with a hydraulic motor - is something whose max RPM is going to be in the ~ 540 range.

How about this one:

2.8 cu in CHAR-LYNN 101-1025 HYD MOTOR

1800 psi cont
2400 psi inter (puts it right in the range of my tractor)

Speed:
969 RPM cont.
1127 RPM int.
Flow:
12 GPM cont.
14 GPM int.

The B3200 is rated at 6.7 gpm according to tractordata.com

If the above motor does 969 rpm at 12 gpm - my calculations show that it should do ~ 524 rpm - at 6.5 gpm.

Seems like that puts me right in the sweet spot GPM / RPM wise.

The above motor only has a 650 in lbs continuous torque rating though - I'm wondering if that would be enough to spin the drum.[/QUOTE]
If you have a 10:1 sprocket ratio and motor on the small sprocket, won't that multiple the torque at the drum the same ratio (X10 = 6500 in/lb. 542 ft/lb.)?

Thanks - I must have had a brain fart when I typed that.

 

[jim_wilson]

Dfkrug - if you're still around....... Do you remember having to do anything special to lift off the back section from the hub - as you showed in this pic? :

I've started taking my mixer apart to convert over to a hydraulic drive - and found the chain is pretty crappy looking (I bought the mixer used at an auction)- I took off the round "cap" that covers the rear of the hub - but the thing doesn't seem to want to come apart.

I looked at some of the parts blowups - and they seemed to indicate that the grease fitting actually goes into the hub and might be keeping it from coming apart.

 

[dfkrug]

Dfkrug - if you're still around....... Do you remember having to do anything
special to lift off the back section from the hub - as you showed in this pic? :

What part of yours is hard to remove? Can you take and post a photo? I am on vaca in Charleston, SC
presently, but on the computer now and then.

 

[jim_wilson]

What part of yours is hard to remove? Can you take and post a photo? I am on vaca in Charleston, SC
presently, but on the computer now and then.

Hey! - Thanks for responding. But I figured it out. I was trying to separate the "tub" assembling from the mount and chain cover - so I could get to the chain (it's all rusted up and pretty lousy looking) - I removed the big round "washer" that's held in with the large hex head screw on the back - but the thing didn't want to separate. After thinking about it for a bit - I lifted the whole mixer up by hanging it from my FEL forks - and then I took a large impact socket - and started whacking on it with a 5 pound sledge (softened the impact with a piece of 2x4) - that started moving it.

It appeared that the bearings were a bit of a press-on fit. I finally got the thing separated.

Now I just have to get a new chain, and get some of the other parts to convert this over to hydraulic power -and I 'll be in business. I'll post some pics tomorrow to add to this thread.

 

[jim_wilson]

Oh yeah - and Charleston is nice. I've been down there a few times. One of my brother's in law lives in Summerville which is just outside of Charleston. Have a good vacation!

 

[dfkrug]

Oh yeah - and Charleston is nice. I've been down there a few times. One of my brother's
in law lives in Summerville which is just outside of Charleston. Have a good vacation!

First time in the state for us. It is my personal #48.

 

[dfkrug]

Well, it has been over 15y since I first started this thread, and I still use my mixer. This is the first implement I bought for my first tractor, back about 1997 or 1998. A Kubota L2550DT.

I just did an upgrade that I threatened to do years ago. It works well.

I was recently pouring concrete. Here is my con-mix loading area. I much prefer shoveling aggregates and Portland to using bags.