Question 1

What is the definition of 'Gross Capacity' as listed in a crane's load chart?

Accepted Answer

Gross Capacity is the total weight the crane is rated to lift at a specific configuration. This includes the payload plus all deductions such as the hook block, headache ball, rigging, and effective weight of the jib.

Question 2

What is 'Net Capacity'?

Accepted Answer

Net Capacity is the actual payload weight you can lift. It is calculated by taking the Gross Capacity (from the load chart) and subtracting all deductions (hook block, ball, rigging, etc.).

Question 3

If a crane's load chart lists a Gross Capacity of 50,000 lbs, and the total deductions (block, rigging, etc.) weigh 2,000 lbs, what is the Net Capacity?

Accepted Answer

Net Capacity = Gross Capacity - Deductions. 50,000 lbs - 2,000 lbs = 48,000 lbs.

Question 4

As the operating radius of a crane increases, the rated capacity generally:

Accepted Answer

As the radius increases (load moves further away), the leverage (tipping moment) on the crane increases, which significantly decreases its capacity to lift load safely.

Question 5

The 'Operating Radius' is measured from:

Accepted Answer

Operating Radius is the horizontal distance from the center of rotation (axis) of the crane to the center of gravity of the freely suspended load.

Question 6

A crane is set up with a boom length of 80 feet. At a 30-foot radius, the load chart shows a Gross Capacity of 25,000 lbs. If the radius increases to 40 feet, the capacity will be:

Accepted Answer

Capacity decreases as radius increases. Therefore, at a 40-foot radius (longer reach), the capacity will be lower than at a 30-foot radius.

Question 7

When determining capacity from a load chart, if the actual boom length falls between two listed lengths, you should generally use:

Accepted Answer

Standard practice (unless the chart allows interpolation) is to use the next longer boom length listing, which typically has a lower capacity, to be conservative and safe.

Question 8

If the actual operating radius falls between two listed radii on the load chart, you must use:

Accepted Answer

Unless the manufacturer specifically permits interpolation, you must always select the next longer radius, which corresponds to a lower, safer capacity rating.

Question 9

Gross Capacity: 18,000 lbs. Hook Block: 600 lbs. Headache Ball: 200 lbs. Slings & Shackles: 150 lbs. What is the Net Capacity?

Accepted Answer

Net Capacity = Gross - Deductions. 18,000 - 600 - 200 - 150 = 17,050 lbs.

Question 10

You are planning a lift. Load weight: 8,500 lbs. Rigging weight: 500 lbs. Hook block weight: 400 lbs. What is the Total Load (Gross Load) applied to the crane?

Accepted Answer

Total Load (Gross Load) = Load Weight + All Deductions. 8,500 + 500 + 400 = 9,400 lbs. This is the number you compare to the Gross Capacity chart.

Question 11

Load chart capacity: 40,000 lbs. Total deductions (block, ball, rigging): 1,200 lbs. Load weight: 35,000 lbs. Can you safely make the lift?

Accepted Answer

Net Capacity = 40,000 - 1,200 = 38,800 lbs. Load is 35,000 lbs. Since 35,000 < 38,800, the lift is safe (Yes).

Question 12

Gross Capacity: 12,000 lbs. Deductions: 1,000 lbs. Load Weight: 11,500 lbs. Can you make this lift?

Accepted Answer

Net Capacity = 12,000 - 1,000 = 11,000 lbs. Load is 11,500 lbs. You are 500 lbs over capacity (11,500 - 11,000 = 500).

Question 13

Which of the following is typically considered a deduction from gross capacity?

Accepted Answer

Load charts usually require deducting the effective weight of jibs (extensions), whether stowed or erected, along with hooks and rigging. Rope and fuel are usually accounted for in the base chart.

Question 14

A crane has a rated capacity of 100,000 lbs at a 10 ft radius. At a 50 ft radius, the capacity is likely to be:

Accepted Answer

Capacity drops significantly as radius increases. At 50 ft, leverage is much higher, so capacity will be much lower.

Question 15

Load Chart Capacity: 25,000 lbs. You are lifting 20,000 lbs (total gross load). What percentage of the crane's capacity are you using?

Accepted Answer

Percentage = (Load / Capacity) * 100. (20,000 / 25,000) = 0.80 = 80%.

Question 16

The 'Boom Angle' is the angle between:

Accepted Answer

Boom angle is defined as the angle between the horizontal ground line and the centerline of the boom.

Question 17

When lifting over the front quadrant with a truck crane, capacity is often _____ compared to lifting over the rear.

Accepted Answer

Truck cranes are generally less stable over the front due to the lack of counterweight effect from the engine/carrier relative to the rear outriggers. Capacities over the front are usually lower or prohibited unless a front stabilizer is used.

Question 18

If a load chart specifies 'On Outriggers Fully Extended', but you only extend them halfway, you must use:

Accepted Answer

You must use the chart that matches your actual configuration. If a mid-extension chart exists, use it. If not, you generally must use the 'On Rubber' (tires) chart as it is the safest, lowest capacity configuration.

Question 19

A 'Range Diagram' helps the operator determine:

Accepted Answer

Range diagrams visually show boom length, angle, height, and radius, helping plan lifts to ensure the crane can physically reach the pick and set points.

Question 20

When a jib is erected but not being used to lift the load (load is on the main boom), you must:

Accepted Answer

An erected jib adds dead weight to the boom tip. You must deduct its effective weight from the main boom's gross capacity.

Question 21

Gross Capacity: 55,000 lbs. Hook Block: 1,200 lbs. Rigging: 500 lbs. Stowed Jib Deduction: 800 lbs. What is the Net Capacity?

Accepted Answer

Net Capacity = 55,000 - 1,200 - 500 - 800 = 52,500 lbs.

Question 22

Which factor usually governs crane capacity for short boom lengths and short radii?

Accepted Answer

At short radii/boom lengths, the crane is very stable (hard to tip). The limiting factor is usually the Structural Strength of the boom or components. (At long radii, Stability/Tipping is the limit).

Question 23

Which factor usually governs crane capacity for long boom lengths and long radii?

Accepted Answer

At long radii, the leverage of the load is high, making the crane more likely to tip over before the boom breaks. Stability governs.

Question 24

If the load chart has a bold line dividing capacities, values above the line are based on ____ and values below are based on ____.

Accepted Answer

Standard convention: Capacities above the bold line are limited by Structural Strength. Capacities below the line are limited by Stability (Tipping).

Question 25

Net Capacity is 8,000 lbs. You have a load of 7,000 lbs. Is this a safe lift?

Accepted Answer

7,000 lbs < 8,000 lbs. Yes, it is safe.

Question 26

A crane's chart lists capacities for 360-degree rotation. This means:

Accepted Answer

360-degree rotation charts provide a capacity that is safe regardless of whether the boom is over the front, side, or rear.

Question 27

You are operating 'On Rubber' (tires). You must:

Accepted Answer

On-rubber capacities depend critically on tire stiffness. You must verify tires are inflated to the manufacturer's specified pressure for lifting.

Question 28

Gross Capacity: 30,000 lbs. Block: 800 lbs. Rigging: 200 lbs. Load: 25,000 lbs. How much spare capacity do you have?

Accepted Answer

Net Capacity = 30,000 - 800 - 200 = 29,000 lbs. Spare Capacity = Net Capacity - Load. 29,000 - 25,000 = 4,000 lbs.

Question 29

When lifting from a jib, the effective weight of the jib is:

Accepted Answer

When lifting *using* the jib (load line on jib), the jib's weight is usually accounted for in the jib load chart itself. You do NOT deduct the jib weight from the jib chart capacity (but check specific notes). However, you MUST deduct the main hook block if it's hanging from the main boom.

Question 30

When using a 'Pick and Carry' chart, the load must be:

Accepted Answer

Pick and carry operations are most stable when the load is directly over the front, aligned with the crane's travel path to prevent side-tipping forces.

Question 31

Gross Capacity at 40' radius is 15,000 lbs. Gross Capacity at 50' radius is 10,000 lbs. If your radius is 45', what capacity should you assume?

Accepted Answer

Always use the capacity for the longer radius (50' -> 10,000 lbs) unless the chart allows interpolation.

Question 32

Rapidly swinging a load can cause the effective radius to:

Accepted Answer

Centrifugal force pushes the load outward during a swing, increasing the operating radius and the tipping moment.

Question 33

Dynamic loading (stopping a load suddenly) can increase the stress on the crane by:

Accepted Answer

Sudden stops create shock loads (dynamic loading) that can momentarily increase the effective weight of the load by 50% or more, potentially causing structural failure.

Question 34

The weight of the hoist rope (wire rope) is usually:

Accepted Answer

For most mobile cranes, the weight of the wire rope is accounted for in the load chart calculation by the manufacturer. However, some heavy lift charts require deducting excess rope. Standard answer is 'Ignored/Accounted for' unless chart notes say otherwise.

Question 35

If a crane is set up on a 1% slope, capacity can be reduced by:

Accepted Answer

Even a small slope (1 degree or roughly 1-2%) creates side loading and increases radius, reducing capacity significantly (often 10-20% for long booms). Charts assume level ground (within 1%).

Question 36

Rated Capacity: 50,000 lbs. You are lifting 45,000 lbs. What is your load percentage?

Accepted Answer

45,000 / 50,000 = 0.90 = 90%.

Question 37

When lifting with a telescopic boom crane, if the boom length is not fully extended or retracted to a detent/pinned position, you must:

Accepted Answer

If the boom is partially extended between pinned positions, use the capacity for the next *longer* boom length to ensure stability.

Question 38

The parts of line (reeving) affects:

Accepted Answer

Reeving increases mechanical advantage. More parts of line = higher lifting capacity (up to the structural limit of the crane/rope). It does not change tipping stability.

Question 39

A load chart lists 'Boom Point Elevation'. This helps determine:

Accepted Answer

Boom point elevation is the vertical distance from ground to boom tip. It determines how high you can lift the load.

Question 40

If a crane is equipped with an extendable counterweight, extending it will:

Accepted Answer

Extending the counterweight moves its center of gravity further back, increasing the resisting moment and thus increasing lifting capacity.

Question 41

Gross Capacity: 80,000 lbs. Net Load (Object): 75,000 lbs. Deductions (Block+Rigging): 4,000 lbs. Can you lift it?

Accepted Answer

Net Capacity = 80,000 - 4,000 = 76,000 lbs. Load is 75,000. 76,000 - 75,000 = 1,000 lbs spare. Yes.

Question 42

For a crawler crane, 'tipping axis' is:

Accepted Answer

The tipping fulcrum for a crawler crane is the centerline of the track rollers (or idler/sprocket depending on orientation).

Question 43

For a truck crane on outriggers, the tipping axis is:

Accepted Answer

On outriggers, the tipping axis is the center of the outrigger pads.

Question 44

If you lift a load submerged in water, the load on the crane will _____ as the object emerges from the water.

Accepted Answer

Water provides buoyancy. As the object leaves the water, it loses that buoyant support, and its effective weight on the crane increases.

Question 45

Using a single part of line with a Safe Working Load (SWL) of 10,000 lbs, can you lift a 25,000 lb load?

Accepted Answer

1 part = 10,000. 2 parts = 20,000. 3 parts = 30,000. You need 3 parts of line to lift 25,000 lbs safely.

Question 46

A lattice boom crane capacity chart typically lists boom lengths in increments of:

Accepted Answer

Lattice boom lengths are usually listed in 10-foot increments (e.g., 40, 50, 60 ft).

Question 47

Chart capacity: 50,000 lbs. Load weight: 48,000 lbs. Rigging: 3,000 lbs. Result:

Accepted Answer

Gross Load = 48,000 + 3,000 = 51,000 lbs. Capacity is 50,000. Overload = 51,000 - 50,000 = 1,000 lbs.

Question 48

When lifting with two cranes (tandem lift), the capacity of each crane should generally be derated to:

Accepted Answer

For tandem lifts, it is standard safety practice to plan the lift such that neither crane carries more than 75% of its net capacity to account for load shifting.

Question 49

The 'Load Moment' is the product of:

Accepted Answer

Load Moment = Load Weight x Radius. This determines the tipping force.

Question 50

If a chart note says 'Capacities do not exceed 85% of tipping load', this crane is likely:

Accepted Answer

US standards (ASME B30.5) typically rate mobile cranes on outriggers at 85% of tipping. Crawler cranes are often rated at 75%. Cranes on rubber are 75%.

Question 51

A headache ball weighs 300 lbs. A 5,000 lb load is attached. What is the total hanging weight?

Accepted Answer

Total hanging weight (Gross Load) = Payload + Ball = 5,000 + 300 = 5,300 lbs.

Question 52

Load Chart: 20,000 lbs. Net Load: 15,000 lbs. Block: 800 lbs. Rigging: 200 lbs. Jib Stowed: 500 lbs. Is this safe?

Accepted Answer

Gross Load = 15,000 (Load) + 800 (Block) + 200 (Rigging) + 500 (Jib Deduction) = 16,500 lbs. 16,500 < 20,000. Yes.

Question 53

Deflection of the boom creates:

Accepted Answer

When a heavy load is applied, the boom bends (deflects) downward and outward, slightly *increasing* the operating radius, which reduces capacity. Operators must compensate for this.

Question 54

Which quadrant produces the least stability for a truck crane operating on tires?

Accepted Answer

Over the side is generally the least stable area for a truck crane on tires due to the narrow tire track width compared to the wheelbase length.

Question 55

The 'Point of No Return' refers to:

Accepted Answer

It describes the tipping point where stability is lost and the crane begins to overturn.

Question 56

Gross Capacity 100,000 lbs. Load 95,000 lbs. Rigging 6,000 lbs. Result?

Accepted Answer

Gross Load = 95,000 + 6,000 = 101,000 lbs. Capacity 100,000. Overload = 1,000 lbs.

Question 57

Snow or ice accumulation on the boom:

Accepted Answer

Ice/snow adds weight to the boom, which acts as a load. It should be removed or accounted for as a deduction.

Question 58

Load chart notes typically specify capacities are based on:

Accepted Answer

All crane capacities assume the load is hanging vertically and freely. Side loading or dragging invalidates the chart.

Question 59

When calculating net capacity, the auxiliary boom nose (rooster sheave) weight must be:

Accepted Answer

If an auxiliary boom nose is attached, its weight is a deduction from the main hook capacity.

Question 60

Gross Capacity: 60,000 lbs. Deductions: 2,000 lbs. You lift 50,000 lbs. What is your remaining (spare) net capacity?

Accepted Answer

Net Capacity = 60,000 - 2,000 = 58,000 lbs. Spare = 58,000 - 50,000 = 8,000 lbs.

Question 61

Which boom configuration usually provides the highest lifting capacity?

Accepted Answer

A fully retracted boom is the shortest and stiffest, offering the highest structural capacity and stability.

Question 62

If the crane is not level within ___%, the load chart capacities are invalid.

Accepted Answer

ASME B30.5 and manufacturer charts typically require the crane to be level within 1% (1 foot drop in 100 feet).

Question 63

Gross Capacity: 22,500 lbs. Hook: 450 lbs. Rigging: 150 lbs. Jib deduction: 600 lbs. Net Capacity?

Accepted Answer

22,500 - 450 - 150 - 600 = 21,300 lbs.

Question 64

A 'Work Area Diagram' shows:

Accepted Answer

Work Area Diagrams define the operating quadrants (Over Front, Over Rear, Over Side) so the operator knows which capacity chart applies.

Load Charts Practice Questions

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