ARMY TM 5-5420-212-10-1
MARINE CORPS TM 08676A-10/1-1
(3)
A’ Peg-Edge of firm ground on the near bank.
(4)
AR Gap-The distance measured between the A and A’ pegs. This is the actual gap to be spanned by the
bridge.
(5)
F’ Peg-Designates the location of the near bank end of bridge (outer edge of bankseat beam). The
distance (determined later), from the A’ to F’ peg is the amount of bridge that will bear on the near bank, known as near
bank bearing. The minimum acceptable near bank bearing is 1.4 m.
(6)
CRB Peg-Designates the position of the capsill roller beam (CRB). The distance from the A’ peg to the
center of the CRB can not be less than 0.9 m, and from the CRB to the F’ peg can not be less than 0.5 m. The placement
of the CRB is determined by using the length of bridge (L), AR Gap, far bank bearing, and bridge overhang (0.5 m) to
obtain an X distance (from A’ to CRB). Placement of the CRB in this manner will ensure minimum effort during the jack
down operation.
(7)
FRB Peg-Designates the position of the front roller beam (FRB). The distance from the CRB to the
center of the FRB (measured center to center) must be 9.1 m.
(8)
RRB Peg-Designates the location of the rear roller beam (RRB). It is placed 4.6 m from the FRB
(measured center to center).
(9)
O Peg-Marks the clear distance behind the capsill roller beam required to construct the bridge. It is
positioned by measuring the R distance, Table 3-24, column (e), behind the CRB peg.
g.
Calculate bearing
The minimum and maximum bearings for all DS bridges are shown in the Table 3-25 and Figure 3-13.To calculate
the actual locations of the F and F’ pegs, the following procedure is used: Near bank bearing = bridge length (L) - (AR
Gap + 0.6 m) Where: Bridge length is obtained from column (d) of Table 3-24. The AR Gap was measured in the first
step of the design procedure. An assumption of 0.6 m is made at this point in the calculation sequence because this is in
the minimum acceptable bearing allowed on the far bank.
TABLE 3-25. Bearings DS 13-22 Bay w/o LRS
Bearings
Near Bank
Far Bank
Minimum
1.4 m
0.6 m
Maximum
2.3 m
2.3 m
h.
Check bearing
(1)
If the near bank bearing is within the minimum and maximum bearing limits, it will not be necessary to
shift the position of the F and F’ pegs. The position will be initially determined, F peg 0.6 m from A peg and the F’ peg will
be placed the distance determined as near bank bearing measured from the A’ peg.
(2)
If the near bank bearing is more than the maximum bearing allowed (2.3 m), it will be necessary to shift
the bearing.
i.
Shift bearing
(1)
Determine the amount of excess near bank bearing by subtracting the maximum bearing allowed from
the amount calculated. At this point decide how to use the excess bearing as follows:
either
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