HOW TO READ A BOOM TRUCK LOAD CHART

How to Read a Load Chart- Canadian Crane Rentals

Using our Manitex 38ton technical specification sheet as a reference (below), this

document will walk you through the method of reading a load chart. There are three

charts that make up a spec sheet. For all charts, if work is being performed at a boom

length not defined on the load chart, the operator must use the load/capacity rating at

the next longest defined boom length or given radius.

The first is the Load Ratings Chart, which provides the crane capacities at certain

boom angles and radius. The second is the Range Diagram, which provides a

snapshot of the boom position when looking at height, radius, and boom angle. The

third is the Allowable Line Pull, Area of Operation and Crane deductions.

Load Ratings: The rated capacities of the main boom are shown in the chart on the left

side titled “Main Boom Load Ratings with Fully Extended Outriggers”. The top row

represents the boom length. The left column represents the operating radius. The rated

crane capacity and boom angle align with a specific boom length and operating radius.

The right side of the charts is for the jib. This chart will only need to be referenced if the

jib is being used. Using a jib will significantly reduce the cranes capacity.

For example, at a 102-ft boom length and 55 ft. radius, the 38124SHL has a rated

capacity of 7620 lbs at a 58 degree boom angle. The right side of the chart has the

same setup, but shows the rated capacities with the optional jibs. For the 38124SHL,

there is a 32’ jibs. Using the jib at the same 55-ft radius reduces the rated capacity is

3250 lbs at a 70 degree boom angle.

Crane Deductions: Deductions also have to be figured into the crane capacities. A list

of possible deductions is shown at the bottom of the main boom chart.

This includes deductions for when the jib is stowed on the boom. Other deductions for

this crane include auxiliary block, ball and hose reel. Deductions will also be required

rigging (everything below the hook).

Allowable Line Pull: Below is a chart that illustrates the parts of line required to reach

each capacity. The crane load line will have to be multi-parted accordingly, depending

upon the capacity that needs to be lifted. For example, the 38124SHL load line has a

capacity of 9,500 lbs with a 5/8” x 6 x 25 IWRC cable. A lift of 15,000 lbs. would require

a two-part line, which would increase the load line capacity to 19,000 lbs.

Area of Operation: This crane has a 360 degree are of operation. This means, this

crane has the ability to pick up the load in all 4 quadrants. Not all cranes have a 360

degree chart.

Range Diagram: The range chart is an aid for the operator in determining how the

boom truck will need to be set up in relation to lifting a particular load. The load radius is

shown at the bottom of the diagram. The height above ground is shown on the left side

of the diagram. Within the diagram, the boom lengths and boom angles are shown. All

of these indicators will assist in positioning the boom truck correctly to lift a load.

The upper right portion of the range diagram shows the outrigger and stabilizer setup for

the particular boom truck model.

The lower right portion of the range diagram shows the area of operation. This machine

has a 360 degree area of operations. However, some boom trucks can only pick over

the rear or have reduced capacities in certain quadrants. This information will be noted

on the bottom of the range diagram.

Additional notes are also listed on the range diagram. The operator will need to read

and understand these notes, prior to operating the crane. For example, restricted chart

areas.