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TM 55-2410-237-14
Table 5-3. Bill of Materials for Blocking and Tiedown of the D7 Crawler Tractor (Reduced) on the M172A1 Semitrailer (Figs 5-3 and 5-4)
Approximate
Item
Description
Quantity
Lumber
Douglas-fir, or comparable, straight-grain, free from material
defects; Fed Spec MM–L-751:
4- by 4-inch
8 linear feet
Nails
Common, steel, flathead; bright or cement coated; Fed Spec
FF-N-105: 30d
20
Wire rope
6 x 19, IWRC; improved plow steel; preformed, regular-lay;
Fed Spec RR-W-410:
½-inch
250 linear feet
Clamps
Wire rope, U-bolt clips, saddled, single-grip, steel, Crosby heavy-
duty, or equal; Fed Spec FF-450; type 1, class 1:
½-inch
80
5/8-inch
30
Chain*
Type I, class 1; welded, steel alloy, ½-inch, 11,400-pound safe
working load; Fed Spec RR–C–271; with two grabhooks equal to or
better than the strength of the chain
20
Loadbinders*
Type 1, plain, 18-½-inch operating lever, with two grabhooks
designed for ¼-inch to ½-inch chain, 8-ton capacity; Fed Spec
GGG-B-325A, NSN 3990-00-274-6746
18
Thimbles
Standard, open-type; ½-inch, type II, Fed Spec FF-T-276
26
*Chains and loadbinders may be substituted for ½-inch wire rope and clamps.
Table 5–4. Application of Materials for Blocking and Tiedown of the D7 Crawler Tractor on the M172A1 Semitrailer (Figs 5-3 and 5-4)
Item
No.
Required
Application
A
4
Track blocking, 4- by 4- by 24-inch lumber. Place one piece in front of and
behind tracks on D7 tractor and toenail with 5 30d nails on each block.
B
26
Thimble, open-type, ½-inch. Place four on each rear tiedown provision, and
three on each front provision (see figs 2-3 and 2-4). Place one thimble on each
semitrailer outside tiedown ring to be used.
*C
20
Wire rope. Each consists of ½-inch wire rope, length as required.
Form complete loops (detail 2, fig 5-3) between tractor diagonal braces (see
fig 2-6) and M172A1 left and right tiedown rings on top of semitrailer goose-
neck (see fig 5-4). Place thimble between wire rope and M172A1 tiedown
rings.
From complete loops between right rear tie-down provision on tractor and four
nearest M172A1 tiedown rings on same side along semitrailer bed. Place thim-
bles between wire rope and tiedown provision on tractor. Place thimbles
between wire rope and M172A1 tiedown rings.
Attach wire ropes to remaining tiedown provisions and tie down in same man-
ner as above.
Form complete loops between tractor tow hook and M172A1 frame between
first and second axles of tandem on both sides. Wrap wire rope around
M172A1 frame for tiedown. Place cushioning material between wire rope
around M172A1 frame if desired.
Form complete loops between D7 tracks behind forward drive sprocket and
rear frame on each side of M172A1. Use cushioning material as necessary
between wire rope and tracks or M172A1 frame. Wrap wire rope around
M172A1 frame and D7 tracks for tie-down. Tension all tiedowns evenly.
CAUTION
Tension tiedowns evenly. Do not exceed 400 pounds of tension on any single
tiedown. Wire rope ends should overlap at least 24 inches. Secure with four ½
5/8-inch clamps (item D).
Clamps, ½-inch (detail 2, fig 5-3). Place four clamps on each wire rope loop at
the overlap area. Space the four clamps 2-½ inches apart, with at least 6 inches
from the free end of the wire rope. Tension wire rope and tighten clamps to
approximately 65-foot-pound torque.
*E
30
Clamps, 5/8-inch (detail 3, fig 5-3).
Secure each ½-inch thimble with one clamp.
*D
80
*Suitable capacity of chains and loadbinders may be substituted for ½-inch wire rope and clamps.
5 - 7
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