Ramp Bay Controls.

Table 5. Improved Ribbon Bridge Operation Hybrid IRB/IFB MLC Ratings

TM-5-5420-278-10 M85 Tank Chassis Transporting: for Bridge Armored-Vehicle-Launched Scissoring Type Class 80 Manual
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TM 5-5420-278-10 0036 00 0036 00-6 BRIDGE OPERATION (Contd) d. Ramp Bay Controls. Prior to allowing vehicle traffic on bridge, bridge OIC checks the ramp cylinder controls. The ramp bay should be let down additionally and pressed to the shore prior to vehicle crossing. Position both ramp cylinder pump levers in the DOWN position, and pump each pump 12 times (25 times if using only one pump. Then place the ramp cylinder pump levers in the TRANSPORT/ CROSSING position. This condition will allow the ramp bay to automatically adjust to any rise in water level. To compensate for falling water level, the pump lever must be placed in the UP position and raised to the desired height until the ramp bay obtains the lower water level. When the ramp bay obtains the proper water level, place the lever in the TRANSPORT/CROSSING position before allowing traffic on bridge. The maximum angle the ramp bay can rise is 20 degrees. Some vehicles, such as Armored Vehicle Launched Bridge (AVLB), must be guided onto the bridge because of the interference of vehicle equipment with bridge deck. CAUTION Before a bridge crossing is performed, the operator must ensure all sharp-edged stones are removed from tire treads, tracks, and roadway surface. Failure to comply may cause dents or puncture holes in roadway. Stopping, accelerating, turning, and shifting of gears on the bridge is not permitted during Caution or Risk crossing, and should be kept at a minimum during Normal crossings. Failure to comply may result in damage to equipment. Bridge commander must observe leading edge of bridge and decrease crossing rating (Normal to Caution to Risk) or halt operations, as necessary, if continuous water is coming over bow dam. e. Traffic. Prior to allowing vehicle traffic on bridge, open longitudinal upper couplings on interior bays only. Note GVW of each vehicle. The capacities of the IRB at various stream velocities are found in table 7. Vehicles may travel anywhere within the yellow lines on the roadway in normal crossings at reasonable speeds. Adjust position of ramp plates as necessary. In Caution crossings, all vehicles are restricted to the center of the bridge and to speeds up to 8 mph (12.87 kph). A 150-ft (45.72-m) tail-to-head spacing is required for Caution crossings, while a 100-ft (30.48-m) spacing is required for Normal crossings. Risk crossings require the following: the vehicle must be on the roadway centerline, it must travel at less than 3 mph (4.83 kph), and only one vehicle is permitted on the bridge at a time. (1) DISTANCE BETWEEN VEHICLES: For standard load, 98 ft (30 m); for exceptional load, 164 ft (50 m). (2) MAXIMUM CROSSING SPEEDS: Under standard load up to MLC 40 12.4 mph (20 km/h) Under standard load up to MLC 40 6.2 mph (10 km/h) Under exceptional load MLC 70 3.1 mph (5 km/h)

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