Table 5-1. Bill of Materials for Blocking and Tiedown of the Tractor-Scraper, M621B on the MB70 Semitrailer.

TM 55-3805-248-14

c. Loading.

The rear axle of the scraper should be over the

rear edge of the last trailer tire.

(1) The vehicle may be driven onto the

NOTE

semitrailer if a ramp is available or backed onto

The tire pressure of the tractor must be

the semitrailer with the semitrailer gooseneck

a t least 45 psi because of the close

extended. However, should physical facilities

clearance of the tractor cab over the

and/or equipment preclude these loading methods,

trailer gooseneck.

the vehicle may be lifted onto the semitrailer by a

(3) The M870 semitrailer gooseneck should be

crane of sufficient capacity. For lifting procedures

r a i s e d to the travel position by use of the

and precautions, see paragraph 6-46.

truck-tractor winch cable, and the semitrailer

CAUTION

should be connected to the M920 truck tractor.

Since the wheel tread (tire width-outside

(4) Data for the application of material re-

to outside of tires) is 119 inches com-

quired to restrain the vehicle are provided in

pared with a trailer width of 96 inches,

table 5-2.

about one-third of each tire will project

CAUTION

beyond the sides of the trailer. Care must

Before the semitrailer is moved, effect

be taken to ensure an equal amount of

lockout of the tractor-scraper's steer-

tire overhang occurs on both sides.

ing/articulation unit by installing two

(2) The tractor-scraper should be parked and

locks on the steering cylinders.

the brakes should be on as shown in figure 5-1.

Table 5-1. Bill of Materials for Blocking and Tiedown of the Tractor-Scraper, M621B on the MB70 Semitrailer.

Approximate

Quantity

Description

Item

Parking Platform

Stacked l-inch plywood, 96 inches wide, 13 sheets high. Construct to

have a 45 slant on both wide edges by starting with a loose sheet 80

inches long. Cut each succeeding sheet 2 inches shorter. (i.e. second sheet

78 inches long, third sheet 76 inches long, etc.) This provides the 45

slants and a 1 inch nailing surface on both wide edges.

Sleeper Shoring/Lateral Blocking 6- x 6- x 50.inch lumber.

Each consists of two. 120-inch-long -inch-diameter chains with hooks on

Chain Assembly*

each end (breaking strength, 45,000 pounds). (This type of chain in shown

in the General Catalog of the Crosby Group Inc., PO Box 3128, Tulsa,

OK 74101; or, in the catalog of McMaster-Carr Supply Company, PO

Box 4355, Chicago, IL 60683.

Load Binders*

-inch in diameter (breaking strength, 45,000 pounds).

Common, steel; flathead. bright or cement coated; para 3.6.11.2 Fed Spec

Nails

FF-N-105B:

500

10d

20d

*Wire rope, 5/8-inch. 16 x 19, IWRC; improved plow steel; performed, regular-lay) clips and thimbles may be substituted for the

chains and loadbinders.

Table 5-2. Application of Materials for Tiedown of Tractor-Scraper OR the M870 Semitrailer (fig 5-1).

Application

Item

No. Required

Parking platform. Place with a slanted edge forward against semitrailer gooseneck hinge

point. Nail sheets to floor and each other with 10d nails.

Sleeper shoring/lateral blocking, 6- x 6- x 50.inch lumber. Place three abreast and stack

three high between tractor wheels along the length of the semitrailer. Shore height to fit

(approximately 18 inches to bottom of engine). Toenail to floor and to each other with 20d

nails.

C, D, E, F

Connect all chains in complete loops to create double the breaking strength of the

assemblies. Pass the chains through the vehicle tiedown devices and through the semitrailer

outside tiedown ring on the same side. from C to D, and on the opposite side, from E to F.

at an approximate 45 angle. Tighten the chains with the loadbinders.

5-3