Why or when should the blender in the hopper rotate backwards (looking from the left side of the pump)? I and every pumper i know allways has the blender to turn clockwise because we believe that it fill the tubes best, in that direction. I´ve tryed to have it to turn backwards many times, and i don´t notice any different in pumping. I´m not a novice in pumping concrete - i own and still pump concrete for my pumpingcompany sins many years - but i´ve never heard the real reason (and why) in wich direction the blender should be rotated. I know it sounds like a novicequestion..have mercy.

Is it frontwards (clockwise) or backwards....and why? 

Having the paddles in the opposite direction really helps with the pumpability of mixes of really harsh mountain rock, lean sand quantity, very high strength concrete and slumps below 2". The idea is to draw some air into the cylinder while its pumping to create air vacuum within the line which can help assist in moving the material.  The rotation of paddles would vary from hopper design according to how to draw air into the delivery cylinders. This works well with hopper full equal or below paddle shaft height.

Boy I learn something every day now. I like the answer. I must be spoiled with good mixes then. I have never done this.

I have pumped 2 inch rock through 9 inch barrells and 5 inch pipe also, and pumped 2 in slump concrete(shotcrete). The largest issue from my experiance that was at the heads, pushing to hard creating packed heads. But learnt something I guess. I reverse auger paddles when i prime, to keep dry matter back so wet matter has a chance to get a good start then auger direction change for cylinder feed. Interesting, my jobs 100% need people on the end of the delivery hose, so I try never to introduce air.

Have others had to reverse the auger for this reason curious. 

I think another answer to auger directions would be mixing wet product with dry, breaking up a stiff mix in hopper and so on. Some travel with concrete thus is settles or seperates thus the auger aggitator helps break this up. Have seen hydrolic kits just for augers to turn durring travel.

i was always told that paddel's in reverse was for helping draw concrete out of the tubes when pulling the ball back....

Good excuse also I guess, never bothered but again good one.

I never reversed them for any reason while pumping normaly. I always have them so that the concrete get pushed to the middle of the hopper..  I almost always have good concrete but maybe I've been in situations where it could have helped..

I wonder.. Does it help avoid buildup on the sides of the hopper when you revers? (specialy schwing hoppers) or does it actualy cause more buildup?? 

Sure it would, say your sitting waiting for mud, and can't cycle the mud with the boom. It pushes conc the oposite way moving some dead spots.

I will try to have the paddles to turn in "wrong direction" and see if it works. Thanks for a good answer!