Mining Silo HPUs EHA Installed Two New Hydraulic Power Units and Controls to Operate the Gates and Chutes onTwo Silos in the Iron Range in Northern Minnesota. IFP North quoted, sold, designed, and programmed this equipment while EHA built the components and installed them on site. The job consisted of removing two old power units, controls and, plumbing that had been installed in the 50’s. We then replaced it with new power units, accumulators, heat exchangers, proportional valves, joy sticks, HMI’s, and all new plumbing. The systems operate the gates and chutes on two silos that fill train cars at the iron mine. Each silo has two sets of gates and chutes for a total of four. As the train travels under the silos the chutes and gates are opened and closed by operators to fill cars with iron ore. Each silo is capable of filling 3 to 4 cars per minute.