Chapter 2. TRANSPORTABILITY DATA - TM-55-3805-248-140007

TM 55-3805-248-14

CHAPTER 2

TRANSPORTABILITY DATA

Section I. GENERAL

vided for use when the vehicle is transported. The

2-1. Scope.

hitch between the two sections is noncushioned.

This chapter provides a general description and

The only contact with the ground is the four

identification photographs of the M621B tractor-

tires, except for the scraper bowl, when it is used

scraper, as well as tabulated transportability

to scrape, and the cutting edge, when the tractor-

characteristics that are necessary for movement

scraper is parked. The transmission is an eight

of the item.

forward speed, semiautomatic power shift with a

foot-pedal-engaged differential lock. The brakes

2-2. Description.

are air-actuated, expanding shoe-type. The park

The M621B tractor-scraper is a wheeled, commer-

brake is on when air is removed.

cial construction, open-bowl-type vehicle with two

axles. The tractor section has two pneumatic

2-3. Transportability Drawings.

rubber-tired driving wheels powered by a single

Detailed side- and end-elevation transportability

diesel engine rated at 330 horsepower. The

drawings of the M621B tractor-scraper, with

scraper section is towed by the tractor section

dimensions and tiedown and lift-provision load-

and has two pneumatic rubber tires on free-

rating capacities, a r e shown in figures 2-2

turning wheels. The articulated steering is hy-

through 2-4.

draulically operated, and a steering lock is pro-

Section II. CHARACTERISTICS AND RELATED DATA

Performance:

2-4. General Transportability Charac-

Maximum speed (eight range) . . 31 mph (50

teristics.

km/h)

These data are applicable to the model number or

Range (empty at 15 mph) . . . 176 miles (186

national stock number (NSN) shown. Changes in

km)

the model number or NSN may affect the load-

Fuel tank capacity. . .135 US gal (510 liters)

ability of the item as related to guidance shown

Turning radius . . . . . . . . . . .36.5 ft. (11.12 m)

in this manual.

Angle of approach . . . . . . . . . . . . . . . . . . . . .17

a Tractor Scraper, Wheeled, M621B.

Angle of departure. . . . . . . . . . . . . . . . . . . . .14

National stock number. . . . 3805-01-153-1854

Ground clearance . . . . . 18.5 in. (0.47 m) with

Line item number. . . . . . . . . . . . . . . . . . . . S56246

bowl raised

Ground pressure (each tire at 35 and 45 psi

Dimensions and shipping data:

inflation pressure):

Length, operational . . . . . . . 499 in. (12.67 m)

Unloaded (curb weight)

Width, tractor, operational. 116 in. (2.95 m)

Front . .42.8 to 50.3 psi (295.1 to 346.8 kPa)

Width, scraper, operational. 136 in. (3.45 m)

R e a r . . .36.4 to 39.8 psi (250.9 to 275.1 kPa)

Tread width, tractor . . . . . . . . 87 in. (2.21 m)

Ground contact area (each tire at 35 and 45

Tread width, scraper. . . . . . . . 86 in. (2.19 m)

psi inflation pressure):

Height, operational.. . . . . . . 142 in. (3.61 m)

Front . . . . 515 to 441 in (0.332 to 0.285 m )

Area, operational . . . . . 471.28 ft2 (43.71 m2)

Rear . . . . . 275 to 248 in (0.177 to 0.160 m )

Cube, operational. . .5,616.06 ft (159.03 m )

Tire type..... 29.5 x 29, 28 ply, E-2, traction

Center of gravity:

type

Above ground.. . . . . . . . . . . .51.9 in. (1.32 m)

Pressure:

From centerline of scraper wheel . .207.9 in.

Front and rear .35 to 45 psi (241.3 to 310.3

(5.23 m)

kPa)

Weights:

Axle Load:

Shipping (with fuel and liquids full). 63,910 lb

Front axle.. . . . . . . . . . . 44,098 lb (20 002 kg)

(28 989 kg)

Rear axle.. . . . . . . . . . . . . 19,812 lb (8987 kg)

2-1