Why is it that almost all brands of pumps have the S-Tube and only 1 have the Rock Valve??? Did schwing use the S-Tube ever, or did they patent the rock valve and no one can use it?

i think the rock valve was made about the same time as the S-tube and they did a better job and pattened it.

the S-tube is cheaper to build and vairiations of copys by others have not been taken to court like schwing has done to putz that did not go anywhere.

cadillac or chevrolet same cost per mile.

i think its on schwings website , i remember seeing one of their trailer pumps uses a S tube valve

its a schwing trailer pump P-305

I was told by someone who should know that Schwing has the patent on both the rock valve and the S tube but Schwing felt the rock valve was better.

Not sure who has the patent on the rock valve. I do know that Putz used to be owned by more than one guy, and ended up a couple of them ventured out to start their own companies, and since all had rights to the S tube patent, they were each allowed to use it, so thats why you see so many manufacturers using the S tube system. As far as seeing both in action regularly, I prefer the S tube. Rock valves require a lot more maintenance due to the rubber kidney seal in the back end. S tubes are more of a pain to work on, but last a lot longer, and they also have a tighter seal, allowing higher pump pressures, and less problems when pumping a shitty mix.

I think you are right, rockvalves are a littlebit more difficult to maintain and stube is simple.

I am not too sure but I think someone once told me that Putzmeister bought out Thomson Pumps to get the S valve design as Thomson were one of the very first to use S valve idea.

The rock valve is under patent for a few more years, perhaps at its expiration they will not renew it and introduce something else because it is dated. 

The S-tube was originally designed by a group I believe was CIFA. Since the original S-tube design there have been many changes to make it adaptable to a wide spectrum of pumps.  Each manufacturer holds their own patents respectively to their design.

Many of us overlook the fact that regardless of the size of the tube or rock it all has to go down a 5 inch pipe, and now worse these 4.4 - 4.5 ect. Wonder why there are plugs and boom bounce ? don't need to be a MIT grad to figure this out.