FM 5-277 PDF

Table A-1 in Appendix A shows the number of parts needed to build a specific Bailey bridge. Failure to do so may result in serious. It is a welded, high-tensile steel truss section 10 feet 3. It weighs pounds kilograms and can be carried by six soldiers using carrying bars.

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Table A-1 in Appendix A shows the number of parts needed to build a specific Bailey bridge. Failure to do so may result in serious. It is a welded, high-tensile steel truss section 10 feet 3. It weighs pounds kilograms and can be carried by six soldiers using carrying bars. The horizontal members of the panel are called chords. Both chords have male lugs at one end and female lugs at the other.

Panels are joined end to end by engaging these lugs and placing panel pins through the holes in the lugs. On the top of the bottom chord are four seatings or dowels. Table lists the holes in the panel. It has a tapered end with a small hole FM for a retainer clip. A groove is cut across the head of the panel pin parallel to the bridge pin retainer hole. Panel pins should be inserted with the groove horizontal; otherwise, the flanges of the panel chord channels make it difficult to insert the retainer clip.

It is used to pin the end posts of the outer and middle trusses in a triple-truss bridge. It is 10 inches The underside of the transom has six holes into which the panel dowels fit. The transom rests on the lower chord of the panel and is held in place with a transom clamp.

The upper side of the transom has six lugs with an additional lug near each end. The stringers and rakers explained later in this chapter attach to these lugs.

Transoms are normally spaced 5 feet 1. Four transoms per bay—two in the middle and one at each end of the panel—are required to support vehicles over class It weighs 7 pounds 3. It clamps the transom to the vertical and bottom chord of the panel. It is tightened by a vise-handled screw. It weighs 68 pounds At each end is an eye, and a chain with a pin attached. This pin is inserted through the eye to the sway brace to the panel. The sway brace is given the proper tension by inserting the tail of an erection wrench in the turnbuckle and screwing it tight.

The locknut is then screwed up against the turnbuckle. Two sway braces are required in the lower chord of each bay of the bridge, except the first bay of the launching nose, and in each bay of overhead bracing. A raker connects the ends of the FM transom to the top of one end of each panel of the inner truss. This prevents the panels from overturning. An additional raker is used at each end of the bridge.

Both ends of the raker have hollow dowels for the bracing bolts. The dowels fit through a hole in the panel and a hole in the transom.

It weighs 44 pounds The bracing frame is used to brace the inner two trusses on each side of the double- and triple-truss bridge. Bracing bolts attach the bracing frames horizontally to the top chords of the bridge, and vertically on one end of each panel in the second and third stories.

It has a hollow conical dowel at each end. The tie plate is used only in tripletruss bridges. It secures the second truss to the third truss using the unoccupied raker holes in the panels at each joint and at the ends of the bridge. A special lug on its head prevents rotation when the bolt is tightened. The bracing bolt is used to attach rakers, bracing frames, and tie plates to panels. It is inserted into the hollow dowels of the braces to draw parts into proper alignment.

It is tapered through half its length to assist in drawing the panels into alignment. Chord bolts join the panels, one above the other, to form double and triple-story bridges. Two bolts per panel pass upward through holes in the panel chords and are tightened with nuts on the lower chord of the upper story.

They are also used to fasten overhead bracing supports to the top panel chord. Each stringer consists of three 4inch There are two types of stringers: plain stringers weighing pounds kilograms and button stringers weighing pounds kilograms.

They are identical except that the latter has 12 buttons which 10 hold the ends of the chess roadway in place. Each bay of the bridge has six stringers: four plain stringers in the middle, and a button stringer on each side.

The stringers are positioned by the lugs on the top of the transoms. A piece of chess is 2 inches 5. It is made of wood and weighs 65 pounds It is notched at the ends to fit between the buttons of the bottom stringer. Each bay of the bridge contains 13 chess, which lie across the stringers and are held in place by the buttons. Chess are held down by ribbands. It weighs pounds It is fastened to the button stringers by four J-type ribband bolts.

The ribband bolt fastens the ribband to the button stringers and ramps. The hook end of the bolt grips the lower flange of the outer beam of the button stringer or ramp. They are placed only on the story carrying the decking.

They are 5foot 8-inch 1. There are two types; male and female, having male and female lugs, respectively. These lugs are secured to the end panels of the bridge by panel pins placed through holes in the lugs. The male and female end posts weigh and pounds End posts have a step to support a transom outside 11 FM the panel at one end of the bridge. In jacking the bridge, the jack is placed under the step. The lower end of the end post has a bearing block with a semicircular groove which fits over the bearing.

A bearing is a welded steel assembly containing a round bar which, when the bridge is completed, supports the bearing blocks of the end posts. During assembly of the bridge, it supports the bearing block of the rocking roller explained later in this chapter. The bar is divided into three parts by two intermediate sections that act as stiffeners.

One bearing is used at each corner of a singletruss bridge and two bearings per corner for a double- or triple-truss bridge. It is used under the bearings to spread the load from the bearings over the ground or grillage. The base plate weighs pounds kilograms and is large enough for the bearings at one corner of a single-, double-, or triple-truss bridge. Bearings can slide 9 inches The numbers 1,2, and 3 are embossed on the edges of the base plate to indicate the position of the plate under the inner truss of single-, double-, and triple-truss bridges respectively.

They are 10 feet 3. The lower surface of the ramp tapers upward near the ends. There are two types of ramps: plain ramps weighing pounds kilograms , and button ramps weighing pounds kilograms. They are identical except that. The ends of the ramps fit into lugs on the transoms at the ends of the bridge. They prevent the transoms supporting multiple-length ramps from over- 12 FM turning and spread the transom load over the ground.

They are held in place by spikes or pickets driven through holes in their base plates. The wood footwalks are 2 feet 6 inches 0. Supported on footwalk bearers, footwalks are laid along the outer sides of the bridge for use by foot troops. Bearers are attached to all transoms and hold the footwalk post. Hand ropes are threaded through two eyes on each post and secured either to holdfasts on the banks or end footwalk posts. The support is a welded metal assembly that weighs pounds It is fastened to the tops of thirdstory panels by chord bolts.

A transom is seated over the pintles on top of the support and secured by cleats over the lower flange held by four nuts and bolts. One support per girder is placed on each bay of bridge. Two side rollers on the flange on each side of the rocking roller frame act as guides for the trusses.

The side rollers can be removed from the flanges by removing split pins from spindles underneath the flange; they then remain loosely attached to the frame by a chain. The rollers distribute the bridge load along the bottom chord during launching.

The maximum allowable load on one rocking roller is 30 tons It consists of a welded housing containing a single roller split in two. The maximum allowable load on one roller is 10 tons 9. Trusses of single-truss bridges can be carried on either half of the roller.


fm 5-277 bailey bridge

Kazilmaran Decking Before the timber decking is laid, weld 3-inch 7. Slide panel in toward center of bridge. Unless an unusually large cleared area exists at the site, no more than three or four unloading parties will be able to work efficiently at one time. Truck-mounted cranes, 5-ton wreckers, or gin poles can also be used. Length, truss type, and type of grillage of The site should be large enough for bridge that would be assembled at site. Determine initial bridge length FM plates.


FM 5-277 PDF






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