Crane Stability
Every IMT factory-installed crane includes a completed stability chart. Any installer other than
IMT also has the responsibility to complete a stability chart. Cranes are tested for stability to
85% of “tipping” based on the balance point for a specific truck and crane combination. The
Stability Test is per SAE J765a.
Figures entered on the stability chart are for a specific truck and crane combination. If the crane
or vehicle are modified or replaced with another, it is necessary to recalculate stability. By
referring to the stability chart for your crane/chassis combination, it is possible to determine the
loads permitted in the derated load range of your crane.The “tipping point” is defined as the
balance point, which per SAE J765a is when the load on the crane is balanced with the load of
the truck and stabilizers. Any additional load will cause the truck to tip. Cranes are tested for
stability to 85% of the balance point.
SET-UP:
1 The testing area must be a flat, hard surface (ideally concrete, but asphalt or hard-packed
gravel is acceptable). Only authorized testing personnel will be in or near the test area. SAE
J765a specifies that the area must be within 1% of level.
2 Position and lower stabilizers until the weight of the crane has been removed from the truck
springs. Use all stabilizers. Make sure the truck is level and all stabilizers are in contact with
the ground.
3 Operate the crane under partial load to assure operator proficiency and proper machine
function.
STABILITY TEST:
1 Extend the crane to full horizontal position, centered over the rear of the truck.
2 From the capacity placard, determine the rated load at the maximum horizontal reach. Place
a weight equal to 118% of that rated load at the maximum horizontal reach (L).
WARNING
At 118% of rated capacity, you are in
overload! Operate the crane very carefully.
Keep the load within 3.9” (0.1 m) of the
ground at all times, and operate controls
slowly.
To Next Page
Loading...
Need help?
General
