TM-9-2320-272-23-4

TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)

TECHNICAL MANUAL; FIELD MAINTENANCE MANUAL; VOLUME 4 OF 5

SEPTEMBER 2012

TM-9-2320-272-23-4 - Page 825 of 1393

INSTALLATION

WARNING

Before hoisting outer boom away from wrecker, ensure inner boom is properly secured to

outer boom as outlined in Step (2). Failure to comply may result in injury or death to personnel.

NOTE

If installing boom assembly, use hardware from old boom.

1.

Install utility chain (Figure 2, Item 2) to secure inner boom (Figure 2, Item 18) to outer boom

(Figure

2,

Item

3).

2.

Attach two utility chains (Figure 2, Item 2) on outer boom (Figure 2, Item 3).

3.

Hoist outer boom (Figure 2, Item 3) over wrecker and position on turntable (Figure 2, Item 9).

4.

Assemble two sleeve bearings (Figure 2, Item 10) and sheave (Figure 2, Item 11), align sheave with holes in

turntable (Figure 2, Item 9) and outer boom (Figure 2, Item 3), and install boom on turntable with pivot pin

(Figure 2, Item 8) and locknut (Figure

2,

Item

12). Tighten locknut 800 to 1,000 lb-ft (1,185 to 1,356 N·m).

5.

Install grease fittings (Figure 2, Items 7 and 13) on pivot pin (Figure 2, Item 8).

6.

Connect two elevating cylinders (Figure 2, Item 14) to boom (Figure 2, Item 3) with two retaining pins

(Figure

2, Item 17), lockwashers (Figure 2, Item 16), and screws (Figure 2, Item 15). Tighten screws

44

to

61

lb-ft (60 to 83 N·m).

7.

Using lifting device and utility chains, lift outer boom (Figure 2, Item 3) and disconnect shipper braces from

boom.

8.

Connect cylinder extension hose (Figure 2, Item 6) and retracting hose (Figure 2, Item 5) to two boom adapter

elbows (Figure 2, Item 4).

9.

Remove utility chains from outer boom (Figure 2, Item 3).

TM 9-2320-272-23-4

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