Field Expedient Firearms

109 70-71

by different kinds of engineer units.

a. The footbridge M1938 is constructed of separate rafts called "bays," each 12 feet long, consisting of a duckboard supported by two floats. (See flg. 118.)

■ 70. Ftxed Bridges.—The most common military flxed bridges are the simple stringer bridge, the trestle-bent bridge, the light portable steel bridge, often called H-10, and the Bailey bridge.

c. The simple stringer bridge is usually short. It consists of three elementary parts: two abutments, a single span of stringers, and a floor. Two types of abutments are used, one for use with soft approach roadways, the other for use with firm roadways. (See flg. 114.) Every engineer soldier should know how to construct a simple stringer bridge. Trestle bridges are merely a succession or simple spans in which the trestles take the place of abutments. Timber stringers are seldom used in spans of over 15 feet or steel stringers in spans of. over 25 feet.

b. The trestle-bent bridge consists of two ur more st linger spans. The supports between the abutments are trestle bents. (See flg. 115.)

108 70

c. The light portable steel bridge (H-10) (flgs. 116 and 117) consists of two trusses (assembled by manpower, In lengths up to 72 feet) supporting a one-track timber deck. The 12-foot girder sections are carried in trucks and bolted together to build the bridge. The deck planks are held In place by siderail clamps, which hold the siderails to the trusses.

d. The Bailey bridge is an English panel bridge buJlt to carry heavy loads. It can carry 70 tons on spans up to 120 feet, but requires time for erection for these loads.

■ 71. Floating Bridges.—There are a number of different kinds of military floating bridges in use. They are carried

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