- TR10 / TR1000 SERIES STRUCTURAL BEAM TROLLEYS-MAX. LOAD PER TROLLEY: 150 LB @ 265 FPM-TWO 5.5” STEEL TROLLEY, STEEL WHEELS-ONE 3” DIA. NYLON SADDLE-FOR FLAT CABLE-TROLLEY FOR S3 & S4 SIZE BEAMS-USE CONTROL BOX FC-BX1 OR FC-BX2