The Power Sweeper is the most useful Rokenbok vehicle, even though it is expensive, slow moving and odd looking. When you set up a Rokenbok world it sin't long and you have little balls scattered about that need picked up. The Loader and the Skip Track can pick up balls stray balls but it takes a lot of action to pick them up. Meanwhile the Sweeper, while slow moving just drives over each stray ball and sucks it up into its cavernous cargo area. It can easily receive balls into its back cargo area as well the front end will lift up so you can reverse the roller to dump balls into cargo bins, etc. Yes, it costs more than some Rokenbok vehicles but it is very versatile to the task of moving balls within the world you will create. The only downside is that it is slow to drive and to dump the cargo.