Under running cranes offer the advantage of the maximum area coverage without reducing floor space by using extra columns for support.  Usually supported from the ceiling structure, under running cranes are generally limited in capacity to about ten tons.  In special circumstances 12 or even 20 tons are possible.

     The single girder under running cranes seen here are the most economical means of providing maximum crane coverage with a capacity of two tons.

     Multiple cranes sharing a runway give an economical means of increasing production while minimizing capital expense.

     For higher capacities and longer spans a double girder under running crane is necessary.