CMAA Class Class A Class B Class C Class D Class E Class F FEM CLASS FEM1 CM ISOM2 FEM1BM ISOM3 ... This class of crane is used in repair shops, light assembly operations, service buildings, light warehousing, etc. Service ... used in machine shops or paper mill machine rooms. In this type of service, the crane will handle loads that ... Contrx double girder bridge cranes are used when capacity and span requirements are too great for a single girder crane to be used. Double girder cranes also provide higher hook heights because the hoist is placed between the cross girders as opposed to under the cross girder. Double girder cranes are also excellent solutions for handling large loads with long spans.