The mixer is a Port-A-Mix 2 cuyd paddle mixer designed for mixing concrete. I liked it because of the heavy construction, conveyor and trailer.
I am using it to mix clay / sand / lime / cement to make compressed earth bricks. The mixture is relatively dry about 10-12% moisture; or a hand full of soil will ball and leave a small cone shape when dropped. The mixer is 8 long tank X 30 dia. The paddles run along the centerline with the motor on one end. The shaft is supported at each end with roller bearings.
There are a couple of problems I am having since I致e redirected the purpose of the machine. (Not in Order) 1) the mixer paddles are about 25-30 deg off the centerline. This presents too broad a surface to the mix and the mixer must push the soil instead of cutting thru it. I致e stalled the unit and ripped the paddles off the arms several times due to the force. With the clay the soil tends to pack and not flow around the paddle. 2) the RPM is too low. An increased RPM will tend to fluff the soil, kick up and break any existing clods. 3) when the lime / cement is added, the mix gets too dry so water must be added. This causes clumping, hence problem #2. 4) I need to redesign the paddles with a 75 deg angle off the centerline to permit the blades to slice thru the mix rather than displace it. A ribbon, double helix style blade seems to be the preferred style for other soil mixer on the market.
I think an increase in HP would help the redesigned paddles cut thru the soil and the increase in RPM would help agitate and mix the soil. I think a larger displacement motor with a lower speed and higher torque might help with the stalling.
Q >>What is desired mixer bowl rpm's? 6-15 per minute??
The current RPM is 12-15. I plan to increase to 80-90 RPM with more pitch to the blades to reduce resistance.
Q >>Is there a gear unit on the mixer?
Q >>What is the current gear ratio between input power rpm (hydraulic motor) and mixer bowl rpm?
Yes, the current motor is geared down. The ration is unknown, but the reducer appears to be a planetary type gear.
Q >> What is the "good" rpm range (decent torque) for this new B&S Vanguard engine? 1800-3000rpm?
B&S is real tight with the torque curves for this engine and do not post them on the Vanguard site. By shear tenacity I致e found that 2500 RPM seems to be the top of the curve.
Q >> It is better to use them where you use the excessive flow for other hydraulic functions.
The hydraulics also run a 10 conveyor and lift cylinders for the mixer.
I believe I致e addressed your questions. With the pics you might get a better idea of what I知 working with.
In the first you can see the motor, side of the tank, lift cylinders and in the back the conveyor.
In the second you see the current Engine pump
In the third you see the layout of the hydraulics.
