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339A Mobile Crane Operator Practice Test: Free Exam Quiz

Q: Can I sample practice questions before subscribing?

Yes. You can take the interactive 10-question readiness quiz directly on this page with no sign-up required, or download our free 30-question printable sample mock exam PDF with step-by-step answer explanations. A subscription unlocks all 1100 Mobile Crane Operator (339A) questions, spaced-repetition review, and AI tutoring.

Preparing for the Red Seal Mobile Crane Operator (339A) exam

The Red Seal (Interprovincial) Mobile Crane Operator (339A) exam tests everything a working operator needs: load charts, rigging calculations, crane setup, outrigger soil bearing pressure, boom assembly, CSA Z150 safety code, and lift planning. Trying to memorize a thousand questions the night before rarely sticks. Research on the Ebbinghaus forgetting curve shows that spaced review holds knowledge better than cramming.

Red Seal Pass gives you a smarter path: a focused set of new questions each day, automatic review of the ones you miss, and clear explanations so you learn why, not just what.

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📥 Free Printable 30-Question Mobile Crane Operator (339A) Mock Exam PDF

Download our 30-question sample mock exam PDF with complete step-by-step answer keys and a blueprint breakdown.

🎧 Listen: the 30 Mobile Crane Operator (339A) Questions, Read Aloud

The same 30 questions as the free PDF, each read aloud with a 5-second pause before the answer and explanation.

Red Seal Mobile Crane Operator (339A) 30 practice questions video

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Official Mobile Crane Operator (339A) exam blueprint

Published by red-seal.ca for the 110-question Interprovincial exam. These weightings decide how many questions you face in each area, so they decide where your study time belongs.

Major Work Activity	Questions	Share
MWA A: Performs common occupational skills	7	6.4%
MWA B: Performs hoisting calculations	20	18.2%
MWA C: Inspects and maintains crane	14	12.7%
MWA D: Performs rigging	13	11.8%
MWA E: Plans lift, prepares site and sets up crane	16	14.5%
MWA F: Assembles, disassembles and transports crane	15	13.6%
MWA G: Operates crane	25	22.7%
Total	110	100%

Exam time 4 hours · pass mark 70%. Source: red-seal.ca official exam breakdown.

10-Question Mobile Crane Operator (339A) Quick Readiness Quiz — with Full Worked Answers

No sign-up and no email required. Take this 5-minute diagnostic quiz to test your current exam readiness. Every answer below includes complete code citations and worked steps — the same standard as the other 1090 questions in the full bank.

⚡ Interactive Readiness Quiz

Click any option (A–D) below to test yourself & reveal the worked explanation.

Question 1 of 10

A 100-tonne hydraulic truck crane is setting up on a compacted granular fill pad beside a new warehouse in Mississauga to erect roof trusses. The pad looks firm, but the lift plan shows outrigger loads of over 40 tonnes at the worst swing position, and the crane arrived with only its bare steel floats. What must be done before the outriggers are set down?

A) Set the bare floats on the gravel, since compacted fill can carry any outrigger load

B) Place mats or pads sized to keep ground pressure below the soil's bearing capacity

C) Set the outriggers at mid extension, so that less load is pushed into each float

D) Leave the tires in contact with the ground, so they take part of the crane's weight

Correct answer: B

Outrigger loads on a bare float can far exceed what compacted fill will carry. Mats or pads of adequate area spread the load so the ground pressure stays below the allowable bearing capacity. Tires must be clear of the ground when the crane is on outriggers.

Question 2 of 10

A crane on a plant site in Fort Saskatchewan has its lattice jib erected on the boom tip, with an overhaul ball reeved on the jib line, but the next load will be lifted on the main hook block. The planner is working out net capacity from the main boom chart. What must be deducted?

A) The jib's capacity, which is added to the main boom rating instead

B) Only the main hook block, since the jib carries none of this load

C) Nothing for the jib, since jib deductions apply only to jib lifts

D) The erected jib's effective weight, the ball on the jib, and the main block

Correct answer: D

When lifting on the main boom with a jib erected, the deductions include the jib's effective weight, anything hanging from the jib tip such as the overhaul ball, the main block and the rigging.

Question 3 of 10

A rigger in Kitchener is making a temporary eye in a wire rope with drop-forged clips, and a new helper is about to fit the first clip with its U-bolt on the long, load-carrying part of the rope. The rigger stops the helper and explains the rule. Which way must the clips be fitted?

A) U-bolt on the tail, saddle on the live line: never saddle a dead horse

B) U-bolt on the live line, saddle on the tail, so the load is gripped firmly

C) U-bolts in alternating directions, so the twisting forces balance out

D) U-bolts all toward the inside of the eye, so they do not catch on things

Correct answer: A

The saddle goes on the live (load) line and the U-bolt on the dead end, or tail. A U-bolt on the live line crushes it and weakens the rope where the load is carried.

Question 4 of 10

During a monthly check on a crane in Regina, a technician uses a vernier caliper to measure the main hoist rope at its high-wear sections and compare the readings with the nominal size. The apprentice is shown the correct method. In what order is the rope measured?

A) Find the worn sections of the rope; compare the result with the limit; measure across the strand crowns; then turn the caliper and measure again

B) Compare the result with the limit; find the worn sections of the rope; measure across the strand crowns; then turn the caliper and measure again

C) Find the worn sections of the rope; measure across the strand crowns; turn the caliper and measure again; then compare the result with the limit

D) Measure across the strand crowns; compare the result with the limit; find the worn sections of the rope; then turn the caliper and measure again

Correct answer: C

The worn sections, such as those over sheaves and at the drum crossover, are found first. The rope is measured across the outer crowns of opposite strands, the caliper is turned 90 degrees for a second reading, and the result is compared with the nominal size and the removal limit.

Question 5 of 10

Because HMPE fibre slings are so light and strong, a rigger at a refinery outage near Edmonton suggests using them on a hot furnace shell. The sling maker's data sheet includes a temperature limit. Above about what temperature do HMPE slings start to lose strength and creep?

A) About 10°C

B) About 200°C

C) About 400°C

D) About 65°C

Correct answer: D

HMPE fibres soften and creep at fairly low temperatures. Makers commonly limit their use to about 65 to 70 degrees Celsius, with lower ratings as temperature rises.

Question 6 of 10

A truck crane is being set up in a narrow laneway in downtown Montreal, where the counterweight will swing within half a metre of a building wall. Pedestrians and workers walk along the lane past the back of the crane. What must be done about the area the counterweight swings through?

A) Nothing extra, since people can see the counterweight moving and step aside

B) Barricade it so no one can be caught between the counterweight and the wall

C) Post one worker at the back of the crane to push people out of the way

D) Paint a line on the ground and allow people inside it when the crane is idle

Correct answer: B

The swing radius of the counterweight creates a crush hazard against walls and other objects. It is barricaded so no one can enter it while the crane is working.

Question 7 of 10

While driving an all-terrain crane along a flat highway near Medicine Hat to reach a site before dark, the operator is tempted to go faster than the speed rating on the crane's thick, heavy-ply tires. Why must the tire maker's speed rating be obeyed?

A) Thick crane tires build up great heat at speed, which can separate the tread and cause a blowout

B) Driving fast overloads the carrier's transmission, so it can fail long before the tires are affected

C) The bead wires stretch at high speed and pull the tires off the rims, whatever the tire pressure

D) Going over the rating only voids the tire warranty, so it has no effect on safety on the road

Correct answer: A

Heavy crane tires have thick rubber that heats up quickly at speed. Exceeding the rated speed overheats them, which can separate the plies and tread and cause a sudden blowout.

Question 8 of 10

While laying out inserts for a 65 m lattice boom at a site near Sarnia, an apprentice notices that several 6 m inserts have the same pin sizes but different part numbers on the boom chart. Why must the inserts go in the exact positions the chart shows?

A) Inserts are numbered by weight, so they must be lifted from lightest to heaviest by the assist crane

B) Inserts are numbered so the pin holes line up without drift pins, and any other order makes the pins hard to drive

C) Inserts can differ in wall thickness and rating, and the heavier ones belong where the bending is highest near the base

D) Inserts in the wrong order make the boom too tall for the transport limits when it is shipped later

Correct answer: C

Inserts that look alike can have different chords and ratings. The chart places the stronger ones where the loads are highest; putting a lighter insert there can lead to a collapse.

Question 9 of 10

A truck crane is set up on outriggers near the edge of a 4 m deep unshored trench on a road job in Guelph, and starts swinging a heavy precast manhole section out over the trench toward the far bank. How does this swing affect the ground under the crane?

A) The trench drains water out of the soil, which raises the bearing capacity under the outrigger nearest to it

B) The trench relieves the soil pressure, so the outrigger nearest it becomes more stable as the load swings toward it

C) The load swings away from the trench, so the loads on all four outriggers become more even as the swing goes on

D) As the load swings toward the trench, the outrigger nearest it takes much more load, which can collapse the trench wall

Correct answer: D

Swinging a load toward the trench puts much of the crane and load weight onto the nearest outrigger. That surcharge can collapse the trench wall and drop the outrigger, so the setback and swing path are planned for the worst case.

Question 10 of 10

Because a downtown utility job in Ottawa takes two days, a crane must stay parked overnight in the curb lane of a busy street where traffic passes all night. The city's permit allows it with conditions, and vandalism is common in the area. In what order should the crane be left?

A) Confirm the overnight permit terms; set the barricades and warning lights; lock the cab and every compartment; then remove the keys and keep them secure

B) Remove the keys and keep them secure; lock the cab and every compartment; set the barricades and warning lights; then confirm the overnight permit terms

C) Set the barricades and warning lights; confirm the overnight permit terms; remove the keys and keep them secure; then lock the cab and every compartment

D) Lock the cab and every compartment; remove the keys and keep them secure; confirm the overnight permit terms; then set the barricades and warning lights

Correct answer: A

The permit's conditions are confirmed first. The barricades and warning lights are set to protect traffic, the cab and compartments are locked, and the keys are removed and kept secure.

339A Mobile Crane Operator Load Charts, Sling Angles & CSA Z150 Reference

Essential formulas, Canadian code standards, and critical numerical thresholds tested on the Interprovincial Red Seal Mobile Crane Operator (339A) exam:

Hoisting / Crane Topic	Formula or CSA Z150 Rule	Exam Application & Key Value
Net Capacity & Gross Load Deductions	Net Capacity = Gross Chart Capacity − All Deductions	Deductions include main hook block, ball, slings, shackles, wire rope, and stowed/erected jib
Bold Line / Asterisk on Load Chart	Above line = Structural Strength \| Below line = Stability (Tipping)	Stability ratings are based on 75% (crawler/rough terrain) or 85% (outriggers) of tipping load
Sling Angle Tension Multiplier	Tension per Leg = (Weight ÷ Legs) × (Sling Length ÷ Vertical Height)	60° = 1.155× \| 45° = 1.414× \| 30° = 2.000×; never rig below 30° horizontal angle
Outrigger Pad Bearing Pressure	Ground Pressure = Max Outrigger Reaction Force ÷ Pad Area	Blocking area must distribute load below soil bearing capacity; Cribbing ≥ 3× pad area
High-Voltage Power Line Limits of Approach	Up to 75 kV: min. 3.0 m (10 ft) \| 75–250 kV: min. 4.5 m (15 ft)	Over 250 kV: min. 6.0 m (20 ft); require dedicated signaller when working near limits
Material Unit Weights for Load Sizing	Steel: 7,850 kg/m³ (490 lb/ft³) \| Concrete: 2,400 kg/m³ (150 lb/ft³)	Water: 1,000 kg/m³ (62.4 lb/ft³) \| Seasoned Hardwood: ~720–800 kg/m³

Worked examples: gross load deductions, sling angle tension and load weight on the 339A exam

On the 110-question Mobile Crane Operator exam, Operates crane (25 of 110 questions), Performs hoisting calculations (20 of 110 questions), Plans lift, prepares site and sets up crane (16 of 110 questions) and Performs rigging (13 of 110 questions) make up two-thirds of the paper. Every candidate must be fluent in load-chart deductions, sling tension factors and material weight calculations:

Worked example 1

At your planned radius, the load chart shows a gross capacity of 18,000 kg. The load weighs 14,200 kg, the main hook block is 450 kg, rigging hardware is 120 kg, and an stowed jib adds 630 kg of effective deduction. What are the total gross load and percent of rated capacity?

Total deductions = 450 + 120 + 630 = 1,200 kg. Total gross load = 14,200 + 1,200 = 15,400 kg. Percent of capacity = 15,400 ÷ 18,000 × 100 = 85.6%.

Answer: 15,400 kg gross load; 85.6% of rated chart capacity.

Worked example 2

A symmetrical 6,000 kg load is lifted with a 2-leg bridle sling at a 60° horizontal sling angle (sin 60° = 0.866, load factor = 1.155). What tension acts on each sling leg?

Vertical share per leg = 6,000 ÷ 2 = 3,000 kg. Sling tension = 3,000 ÷ 0.866 = 3,464 kg per leg. (At a 30° horizontal angle where sin 30° = 0.5, tension doubles to 6,000 kg per leg.)

Answer: 3,464 kg per leg.

Worked example 3

What is the weight of a solid steel plate measuring 4.0 m long × 1.5 m wide × 25 mm thick? (Unit weight of steel = 7,850 kg/m³.)

Convert thickness to metres: 25 mm = 0.025 m. Volume = 4.0 × 1.5 × 0.025 = 0.15 m³. Weight = 0.15 m³ × 7,850 kg/m³ = 1,177.5 kg.

Answer: 1,177.5 kg (≈ 1.18 tonnes).

Always use the crane manufacturer’s specific load chart, quadrant definitions and CSA Z150 safety code rules.

A 4-week study plan for the Mobile Crane Operator (339A) exam

18 new questions a day is the pace the platform sets, because spacing beats cramming. Over four weeks that is about 504 questions, and the order below follows the official weightings above.

Week 1 — the heaviest area. MWA G: Operates crane, which alone is 22.7% of the exam.
Week 2 — the next two. MWA B: Performs hoisting calculations (18.2%) and MWA E: Plans lift, prepares site and sets up crane (14.5%).
Week 3 — the remaining activities, plus every question you got wrong. Wrong answers return automatically on day 1, 3 and 7.
Week 4 — full-length timed runs. 110 questions in 4 hours, then review every mistake by Major Work Activity.

Booking the Mobile Crane Operator (339A) exam where you live

Eligibility and booking are handled by your province, not by the Red Seal program itself. Start here:

The full question bank

1100 Mobile Crane Operator (339A) questions, every one explained

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Frequently asked questions

How many questions are on the Red Seal Mobile Crane Operator (339A) exam?

The Interprovincial Red Seal Mobile Crane Operator (339A) exam has 110 multiple-choice questions, a 4-hour limit and a 70% pass mark, per the official exam breakdown on red-seal.ca.

Can I sample practice questions before subscribing?

Yes. You can download a free 30-question sample mock exam PDF with full step-by-step answer explanations. A subscription unlocks all 1100 questions, spaced-repetition review, and AI tutoring.

What's the best way to study for the Red Seal exam?

Consistent daily practice beats cramming. Read our Founder's Exam Prep Journey Blog Series to see how daily spaced repetition works in practice.

What does a subscription cost?

We offer a 7-Day Pass ($9.99 CAD one-time), a Monthly Pass ($29.99 CAD/month), and a 3-Month Pass with Free-Until-You-Pass Guarantee ($69.99 CAD one-time). All plans include daily adaptive practice, spaced-repetition review, and AI Journeyperson Tutor coaching.

What extra practice comes with the 3-Month Pass?

The 3-Month Pass adds two study tools for Mobile Crane Operator (339A). Practice by Block lets you pick any Major Work Activity on the official blueprint and drill it 18 questions at a time. Exhibit Booklet Practice gives you 12 questions that make you read tables, catalogs, test records and a hydraulic truck crane set up on outriggers, with a worked explanation for every answer.