TM 5-5420-209-12
Section III. TECHNICAL PRINCIPLES OF OPERATION
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1-13
General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10 —
1-14
Detailed Principles of Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10
1-13. General. The Improved Float Bridge (Ribbon Bridge) is a modular bridge with an integral superstructure and float-
ing supports. A complete ribbon bridge consists of a ramp bay at each bank and the required number of interior bays to
complete the bridge between the two ramp bays. The bridge has a roadway width of 13 ft 5 in. (408.9 cm). The bridge
is capable of crossing a class 70 load in currents up to 8 ft/sec (243 cm/sec). Individual bays may be joined to form a raft
for ferrying operations.
1-14. Detailed Principles of Operation.
a. Transporter. The transporter is either a modified U.S. Army M812 or M945 truck chassis which provides a self-
contained unit for transporting, launching, and retrieving the bays, boats, and cradles. A hydraulically operated boom
mounted at the rear of the transporter works in conjunction with an 11,000 lb (4,994 kg) capacity winch to provide loading
and unloading capabilities. An operator’s control stand located at the left rear of cab contains all hydraulic controls the
operator needs to unload and retrieve bays.
b. Interior Bay. Each interior bay is a four ponton folding section consisting of two roadway pontons and two bow
pontons. All four pontons are joined together by hinges and pins along adjacent edges. Latches secure the bays in either
the open or folded positions. Each roadway ponton is divided into two separate water tight compartments. The roadway
pontons are the main Ioad carrying members of the bridge. The bow pontons provide additional floatation and a personnel
walkway. When the interior bay is unloaded from the transporter into water and all the Iatches securing the bay in the folded
position have been unlatched, the bay will automatically unfold. When recovering an interior bay Iifting from a single point,
either the front or rear hinge pin lifting eye, will close the bay to the folded position and the latches will secure the bay in
the folded position. The interior bay can be loaded onto the transporter either end first.
c. Ramp Bay. Each ramp bay is a four ponton folding section consisting of two roadway pontons and two bow pon-
tons. All four pontons are joined together by hinges and pins along adjacent edges. Latches secure the bay in either the
open or folded positions. Each roadway ponton is divided into two separate water tight compartments. The roadway pon-
tons are the main load carrying members of the bridge. The bow pontons provide additional flotation and a personnel
walkway. The shore end of the ramp bay is tapered and two approach ramps are hinged to the roadway pontons. Two
hydraulic pumps and cylinders are mounted in the roadway pontons and permit the entire ramp bay to be raised from 0-20
degrees (0-0.349 radians) to accommodate various bank conditions. When the ramp bay is unloaded from the transporter
into water and all the latches securing the bay in the folded position are unlatched, the bay will automatically unfold. When
recovering a ramp bay, lifting from a single point, the hinge pin lifting eye will close the bay to the folded position and the
latches will secure the bay in the folded position. The ramp bay must be loaded onto the transporter water end first or
else the bay cannot be loaded onto or properly secured to the transporter.
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