I can shed some light on this subject,I worked for federal express {AGFS} 8 yrs all 747,727,DC10 aircraft have roller floors running lenght of crgo deck steel containers loaded with freight some weighing up to 3,000 lbs are easily manuevered back to front until all positions are full.I also drove tractor trailers 53ft,pup trailers 27 ft,and straight trucks all have roller decks air activated with a push/pull of lever.rollers run full lenght of deck can give you any insight as to where or who installs these systems.anyway these vehichles were originally made to transport same types of containers they load on aircraft.these vehicles function to interface with aircraft onload/offload as well as each other back to back trailers,straight trucks very handy.I also was a class heavyweight courier,delivered/pickup skids,pallets,wood boxs,containers off all types boxed car parts all these can moved across rollers however there are certain problems these rollers were made for SPECIFIC PURPOSE, BROAD FLAT SMOOTH BOTTOM SURFACES MOVE EXCESSIVE WEIGHT 3,000 LBS AND MORE ON THESE ROLLERS WITH EASE uneven surfaces,narrow surfaces,broken surfaces,delicate surfaces, cause problems that once one learns the ins outs become quite manageable,there was no type of container,pallet,box,or piece that I could not move across the rollers quite easily after figureing out exactlty how it needed to be done.I did the heavyweight thing four years commercial and residential sometimes no docks, forklifts only liftgate, rollers were very beneficial to get freight back to liftgate down of truck after a couple years we all started useing pallet jacks however there were many times I chose to use rollers rather than pallet jack.you do need load locks for freight even though the rollers can be deactivated and retract to below surface of floor,leaving rollers up can be disastourous even though the rollers deactivated automatically when brakes were disengaged but still leaving enough pressure if freight was not secured to roll a considerable distance,there is another means of loading freight on these rollers, we called them pancake,cookie sheets large flat steel sheets originally used for oversized freight that would not fit in containers heavyweight division utilized them. Im sure these would be a costly investment definitley specialty equipment,as well as roller system.we loaded freight on sheets,sheets had large crgo nets with attachable clips all the way around perimeter of sheet put all freight on the sheet throw cargo net over nothings comeing of sheet unless it flips almost impossible unless very top heavy setting inside staight truck or trailer dont recall exact dimentions probaly 2 inches clearance on each side of truck box 6-7 ft long.only disadvantage being you have to know exactly how your stops have to come of and load sheets accordingly or it will be self defeating you can load sheets 6 ft high 3,000-4,000 lbs move with ease across good set of rollers.I will not go on anymore about this subject just wanted to share what I know about this topic I could answer more specifically to any questions.you all have a good CHRISTMAS,STILL LOOKING FOR A DRIVING JOB TAKE CARE