The distribution pipe will do that. Say you have 10 machines all needing 2 coal, you put the distribution pipes all along where the normal pipes are except the last one, you set all the output except the one going into the machine and the one going to the next pipe to 0 then on the machine one you set it to 2 and the exit to the next pipe to 18, then the next pipe you do the same except you set it to 2 and 16, then 2 an 14, then 2 and 12 and so on.