PTSILO

Each silo has two access gates, one on the second ring and one on the roof. Valve located on the second ring is for accessing the inside of the silo when the silo is empty and the the valve located on the roof is for when the silo is full. 

The valve on the second ring consists of two doors and when the silo is full, the load prevents the second door from opening,therefore safeguarding the grain inside from falling out.