Boom truck sizes: what the ton class means

R 03 mWhat the ton number means, and what it does not

Boom trucks are bought, sold and rented by a ton class: a 17-ton, a 30-ton, a 45-ton. Treat the number as the headline rating, the best-case figure on the truck's load chart. No Canadian rule we found defines it, and it does not tell you:

• The capacity at your radius. It falls steeply as the load moves out.
• The set-up it assumes. IHSA notes that full "on outriggers" ratings apply only with every outrigger beam fully extended and all tires clear of the ground; partial extension needs its own chart, or the on-tires rating applies¹.
• Which ton. "Ton" can mean a short ton, a long ton or a metric tonne, and the class does not say.

Canadian regulators that print both units pair them like this: Alberta writes 4.5 tonnes (5 tons) and 59 tonnes (65 tons)², Manitoba 7.3 tonnes (8 tons) and 40.8 tonnes (45 tons)³, and Nova Scotia 91 t (100 tons) beside its 4.5 t (5 ton) line⁴. In every pair the tonne figure is about nine-tenths of the ton figure, implying a ton of about 0.9 tonne, but the sources do not say which ton.

Others use one unit: Saskatchewan's line is 15.5 tons⁵, and Ontario's is in pounds, about 13,608 kg (30,000 lb as written)⁶. So an ad's "30-ton" could be either. CSA Z150:20 makes SI values the units of record, with figures in parentheses for information only⁷, so read the chart in kg.

R 06 mCapacity falls as radius grows

Load radius is the horizontal distance from the crane's centre of rotation to the load hook with the load on, and IHSA notes it grows under load as the boom and machine deflect¹. It is not boom length.

A published chart shows how fast capacity drops. In a non-Canadian reference, NT WorkSafe's example knuckle-boom chart falls from 4,550 kg at 2.89 m to 730 kg at 12.55 m⁸. Computed from those two points, the long-radius figure is about one-sixth of the short-radius one.

Read as load times radius, the same non-Canadian reference chart holds near 13.0–13.5 tonne-metres out to 8.33 m, then falls to about 9.2 at 12.55 m⁸. On that chart, doubling the radius roughly halves the load until other limits govern.

The chart reflects two kinds of limit. CSA Z150:20 separates ratings governed by stability (clause 4.1.1) from ratings governed by structural competence (clause 4.1.2)⁹. The stability margin is fixed in the standard (CSA Z150:20, 2020 edition; provinces may cite another edition): a boom truck with stabilizers fully extended and set is capped at 85% of the tipping load¹⁰, and a wheel-mounted crane on rubber, without outrigger support, at 75%¹⁰.

At the same radius, two more things move the number:

• Where the boom points. Capacity is normally greatest over the rear, less over the side, and may be nil over the front, depending on the quadrant chart¹.
• Level. In one IHSA example, a crane 1 degree out of level lost 10% of chart capacity with a short boom at minimum radius¹, and 30% with a long boom¹.

The rest of the chart is explained in how to read a load chart.

R 09 mReach and tip height

"How high can a boom truck reach?" has no single answer, and no Canadian source we found publishes reach by ton class. The truck's range diagram gives it. Geometry gives a fair estimate: for a straight boom of length L at angle A from horizontal, radius is about L × cos A plus the boom foot's offset from the centre of rotation, and tip height about L × sin A plus the foot pin height; under load the real radius is larger because the boom deflects¹.

Lowering the boom buys radius and costs height, and every metre of radius costs capacity. The angle reading is not exact: IHSA warns that boom angle indicators can be off by as much as 2 degrees and prefers measured radius for critical lifts¹. On the example boom at 60°, 2 degrees is about 0.6 m of radius (computed).

Tip height is not hook height: subtract the hook block, slings and load, then leave clearance. The boom reach calculator does the geometry.

R 12 mThe size bands regulators use

Regulators draw lines at rated capacity, each in its own unit. The lines decide who may operate the truck and, in Manitoba, what counts as a boom truck. Units are as each source publishes them:

Mobile cranes have their own lines: Alberta's hydraulic mobile crane trade starts at 13.6 tonnes (15 tons)¹⁶, and BC certifies hydraulic mobile crane operators at 20 tonnes and under, 80 tonnes and under, and unlimited¹⁷.

Rate schedules band boom trucks by lift capacity in kilograms. Published rates are benchmarks for public works, not quotes; both below are bare (operator not included).

Between listed sizes, Ontario sets hoisting equipment rates by straight-line interpolation, rounded to the nearest five cents¹⁹. New Brunswick lists its boom truck lines, from $166.25 an hour, in its section for non-current equipment¹⁸.

R 15 m30-ton class boom trucks

A 30-ton truck is rated 30 tons or 30 tonnes; the data plate says which. Either way the rating sits above 20 tonnes and below 40, so in most provinces both readings land on the same side of every line.

Rate schedules do not use ton classes, so price from the plate's kilograms. Example: if the plate says 30,000 kg, Ontario's April 2024 schedule interpolates between its 25,000 kg line at $247.90 and its 40,000 kg line at $368.95 to $288.25 an hour, bare (computed)¹⁹. New Brunswick's 2026 schedule puts everything from 25,001 kg up on one line, $268.00 an hour, bare¹⁸.

One trap: Prince Edward Island's 2026 "30-ton" line, $206.72 an hour operated, is a mobile hydraulic crane²¹. PEI prices boom trucks by axle count, such as a tandem-axle boom truck at $125.52 an hour, operated²¹.

R 18 m45-ton class boom trucks

At 45 the unit starts to change answers. Manitoba's legal definition of a boom truck hoist stops at 40.8 tonnes (45 tons)³. A truck sold as a 45-ton may sit at that ceiling or above it, depending on which ton the seller means; one rated 45 tonnes is above it, outside the definition. Either way Manitoba requires an authorized crane and hoist operator at 7,300 kg or more²²; ask Apprenticeship Manitoba which certificate fits.

On rates, Ontario's April 2024 schedule has a 40,000 kg boom truck line at $368.95 an hour, bare¹⁹. PEI's 45-ton line, $229.24 an hour operated, is again a mobile hydraulic crane²¹.

R 21 mThe chassis: GVWR class, axles and legal weights

The crane's rating says what it lifts. The chassis decides who may drive it, where it may go and what it can carry.

GVWR is the manufacturer's maximum design loaded weight, and the same federal regulations treat any Class 7 or 8 vehicle that is not a tractor as a vocational vehicle²³.

Legal weights come from the interprovincial agreement on vehicle weights. For a straight truck: a steering axle may carry 7,250 kg²⁴, a single non-steering axle 9,100 kg²⁴, and a tandem group with a 1.2–1.85 m spread 17,000 kg²⁴. A three-axle straight truck may weigh 24,250 kg gross and a two-axle truck 16,350 kg²⁴, within 12.5 m long, 2.6 m wide and 4.15 m high including the load²⁴.

The straight-truck category lists no tridem drive, and each province may allow heavier weights or other configurations²⁴. Ask the supplier how the truck is registered and whether the move needs a permit.

Axles also set the licence: in Alberta, Class 3 for three or more axles²⁵ and Class 5 for two²⁶; in BC, Class 3 explicitly includes a mobile truck crane²⁷; in Ontario, Class D above 11,000 kg²⁸. See licence class and NSC.

R 24 mMatching size to the job

Size a boom truck from the lift, not from the ton class. The steps:

1. Weigh the load. BC requires each load's weight to be determined and passed to the operator and rigger, or the crane must have a load weight indicator or overload prevention system²⁰.
2. Add the rigging. Hook block, slings and shackles count as load¹.
3. Measure the radius at the pick and at the set, from the centre of rotation, and use the larger.
4. Add a margin. IHSA recommends at least a 5% working margin over the capacity the lift needs¹. For duty-cycle work, manufacturers usually cut chart ratings by 20% or supply a separate chart¹.
5. Ask for the chart. Ask the supplier for the chart capacity at your radius, over the quadrant you will lift in, with the outriggers you can actually set.

Two lines turn a size question into a paperwork question. Alberta requires a lift calculation for any lift over 75% of a crane's rated capacity²⁹. BC treats a boom truck lift over 90% of rated capacity at more than 50% of the maximum permitted radius as a critical lift²⁰.

The size estimator runs these steps and flags both lines.