Booms

TB 43-0142

(6) Worn, cracked, or distorted parts such as pins, bearings, shafts, gears, rollers, and

clamping devices.

(7) Electrical apparatus, for signs of pitting or any deterioration of controller contactors,

limit switches and pushbutton stations.

(8)

Excessive wear on brake and clutch system parts, linings, pawls, and ratchets.

(9) Load, boom angle, wind, and other indicators over their full range for any significant

inaccuracies. For all of the above indicators, the indicated value shall be no greater than 119

percent, and no less than 97 percent of the actual (true) value. For any conversions required by the

operation, such as converting boom angle degrees into radius feet, a conversion chart shall be

provided.

(10) Gasoline, diesel, electric, or other power plants for improper performance or

noncompliance with safety requirements.

(11) Steering, braking, locking, and travel devices for malfunction.

(12) Excessively worn or damaged tires or tracks, when applicable.

(13) Excessive wear of chain drive sprockets and excessive chain stretch.

b. Booms. Check for bends, distorted sections, broken welds, excessive corrosion, loose bolts

or rivets, and operable weights and boom angle indicator.

NOTE

Usage and testing of repaired (rebuilt) and or modified lattice

type booms is authorized only upon approval by the National

Maintenance Point (NMP).

c. Drums, Sheaves, Pulleys. Check for:

(1)

Smoothness and freedom from surface defects.

(2) Eccentric bores, cracked hubs, spokes, or flanges. (Any of these defects will cause the

crane to be removed from service.)

(3) Size and configuration of grooves. A sheave or pulley with a ten percent increase in

groove depth or internal flange width due to wear or distortion shall be replaced.

(4) Sheave pitch diameters:

(a) Boom hoisting sheaves shall have pitch diameters of not less than fifteen times the

nominal diameter of the wire rope used.

(b) Load hoisting sheaves shall have pitch diameters of not less than eighteen times the

nominal diameter of the rope used.

(c) Hook block sheaves shall have pitch diameters of not less than sixteen times the

diameter of the rope used.

(5)

Cracked or worn sheaves and drums.

(6) Proper sheave diameter. The minimum safe operating and the critical diameters given

by rope manufacturers are in Table A-1, where "d" is the nominal diameter.

A-3