Free MASS Test Load Charts and Capacity Questions and Answers 1 — Questions and Answers
Question 1: An operator's load chart indicates a gross capacity of 30,000 lbs for a specific lift. The rigging includes a 750 lb hook block, 450 lbs of slings and shackles, and a 1,200 lb spreader bar. What is the maximum weight of the load (net capacity) that can be safely lifted?
- 30,000 lbs
- 29,250 lbs
- 27,600 lbs (Correct answer)
- 28,800 lbs
Correct answer: 27,600 lbs
Net capacity is calculated by subtracting the weight of all rigging and lifting attachments from the gross capacity listed on the load chart. The calculation is: 30,000 lbs (Gross Capacity) - 750 lbs (Hook Block) - 450 lbs (Slings/Shackles) - 1,200 lbs (Spreader Bar) = 27,600 lbs.
Question 2: On a hydraulic crane's load chart, capacities listed above a bold line or in a shaded area indicate that the lifting limit is based on which factor?
- The stability of the crane against tipping.
- The hydraulic system's maximum pressure.
- The structural strength of the crane's components. (Correct answer)
- The capacity when lifting over the rear only.
Correct answer: The structural strength of the crane's components.
The bold line on a load chart separates capacities limited by stability (tipping) from those limited by structural strength. Capacities above the line are based on the structural integrity of the boom and other components, where failure could be sudden and catastrophic. Capacities below the line are based on the crane's stability and its resistance to tipping.
Question 3: Which of the following is NOT a required deduction from the gross capacity found on a load chart to determine the net lifting capacity?
- The weight of the hook block.
- The weight of the crane's counterweight. (Correct answer)
- The weight of slings and shackles.
- The effective weight of a stowed jib on the main boom.
Correct answer: The weight of the crane's counterweight.
The counterweight is an integral part of the crane's structure, and its weight is already factored into the load chart's capacity ratings. Deductions are items suspended below the boom tip, such as the hook block, rigging, spreader bars, and even the weight of a stowed jib, as they add to the total load being handled by the boom.
Question 4: A crane operator is told to set up for a lift on a surface with a 3-degree side slope. According to standard industry practice and manufacturers' requirements, how does this affect the validity of the load chart?
- The capacity is reduced by 10%, but the lift can proceed.
- The load chart values are still valid as long as outriggers are fully extended.
- The load chart is void because it is predicated on the crane being perfectly level. (Correct answer)
- The operator must use the 'on-rubber' chart instead of the 'on-outriggers' chart.
Correct answer: The load chart is void because it is predicated on the crane being perfectly level.
Crane load charts are calculated based on the crane being set up on a firm, level surface (typically within 1% grade). Operating on a slope introduces dangerous side loading on the boom and compromises stability, making the load chart values invalid and the lift unsafe. The crane must be leveled before proceeding.
Question 5: When reading a crane's load chart, the term "Gross Capacity" or "Rated Capacity" refers to the total weight that can be lifted at a specific radius and includes which of the following?
- Only the weight of the object being lifted.
- The weight of the object, all rigging, and the hook block. (Correct answer)
- The weight of the object plus a 15% safety factor.
- The maximum load allowed during high-wind conditions.
Correct answer: The weight of the object, all rigging, and the hook block.
Gross Capacity is the total load the crane can support at a given configuration, as indicated on the chart. This value includes the actual load to be lifted (net load) plus all capacity deductions like the hook block, rigging, spreader bars, etc.
Question 6: An operator plans a lift calculated to be 85% of the crane's rated capacity. However, the wind speed is forecast to be 25 mph. What is the correct course of action?
- Proceed with the lift as planned since it is within the rated capacity.
- Increase the swing speed to counteract the wind's effect.
- Halt the lift and consult the manufacturer's guidelines for wind speed limitations. (Correct answer)
- Add 500 lbs to the load calculation to account for wind pressure.
Correct answer: Halt the lift and consult the manufacturer's guidelines for wind speed limitations.
Load charts are based on ideal, calm conditions. Wind exerts significant side-loading on the boom and the load, which can destabilize the crane. Operators must adhere to the crane manufacturer's specified maximum wind speed for operation, which is often around 20-25 mph for mobile cranes. Exceeding this limit requires stopping the operation.
Free MASS Test Load Charts and Capacity Questions and Answers 1
An operator's load chart indicates a gross capacity of 30,000 lbs for a specific lift.
The rigging includes a 750 lb hook block, 450 lbs of slings and shackles, and a 1,200 lb spreader bar.
What is the maximum weight of the load (net capacity) that can be safely lifted?