National Commission for the
Certification of Crane Operators
Committed to Quality, Integrity, and Fairness in Testing since 1995

CERTIFICATIONS

Mobile Crane Operator

Written Exam - Answers to Sample Questions

American - Lattice Boom Crawler Crane (LBC)

Following are the answers to the American LBC sample questions.

Sample Item #1

Configuration Side Frames Extended Extension N/A
Counterweight 58,100-lb. Ext. Off-set / Angle N/A
Main Boom 110-ft. Block N/A
Main Boom Angle N/A Ball 700-lb., 1-part of line
Radius 45-ft. Rigging 500-lb.
Other N/A Main Rope 2-lb./ft.
Other N/A Aux. Rope N/A

Note: For line in use, when wire rope deductions are required, the wire rope length shall be measured from the boom tip to the ground.

What is the net capacity when lifting off the main boom?

A. 21,540 lb.
Correct.

Gross Capacity
22,740
Ball
700
Rigging
500
Total Deducts
1,200
Net Capacity
21,540

  
B. 23,450 lb.
Incorrect. Wrong gross capacity due to line pull.

C. 22.740 lb.
Incorrect. Line pull capacity.

D. 22,040 lb.
Incorrect. Forgot rigging.

Sample Item #2

Configuration Side Frames Extended Extension 50-ft. Jib
Counterweight 58,100-lb. Ext. Off-set / Angle 15-degree offset
Main Boom 170-ft. Block N/A
Main Boom Angle 72-degrees Ball 450-lb.
Radius N/A Rigging 320-lb.
Other N/A Main Rope N/A
Other N/A Aux. Rope 2-lb./ft.

Note: For line in use, when wire rope deductions are required, the wire rope length shall be measured from the boom tip to the ground.

What is the net capacity when lifting off the jib?

A. 7,600 lb.
Incorrect. Gross capacity.

B. 7,380 lb.
Incorrect. Used higher boom angle at 73.1 degrees.

C. 5,100 lb.
Incorrect. Used 25 degree offset.

D. 6,830 lb.
Correct.

Gross Capacity
7,600
Ball
450
Rigging
320
Total Deducts
770
Net Capacity
6,830

Sample Item #3

Configuration Side Frames Extended Extension N/A
Counterweight 58,100-lb. Ext. Off-set / Angle N/A
Main Boom 130-ft. Block 1,200-lb., 2-parts of line
Main Boom Angle N/A Ball N/A
Radius 65-ft. Rigging 450-lb.
Other N/A Main Rope 2-lb./ft.
Other N/A Aux. Rope N/A

Note: For line in use, when wire rope deductions are required, the wire rope length shall be measured from the boom tip to the ground

What is the net capacity when lifting off the main boom?

A. 14,000 lb.
Incorrect. No rope deductions.

B. 13,764 lb.
Correct.

Gross Capacity
15,650
Block
1,200
RIgging
450
Main Rope
236
Total Deducts
1,886
Net Capacity
13,764

  
C. 17,344 lb.
Incorrect. Used higher boom angle at 64.7 degrees.

D. 15,650 lb.
Incorrect. Gross capacity.