Side Capacity With a Partially Extended Outrigger
Use the following capacity table for a 30-ton boom truck with 70 ft of boom and fully extended outriggers. Capacities are gross, in pounds, and include the boom, hook block, and all attachments; rigging and hook block must be deducted.
Radius | Over rear | Over side, outriggers fully extended | Over side, outrigger beam not fully extended 25 ft | 11,200 | 9,400 | 6,700 30 ft | 9,800 | 8,200 | 5,900 35 ft | 8,400 | 7,000 | 5,000
The load is a 7,200 lb generator. Slings, shackles, and spreader bar weigh 180 lb; the hook block weighs 320 lb. The crane is positioned so the boom will swing over the passenger side. The operator has extended the outrigger beam on that side only 4 ft of its 6-ft travel because a fence is in the way. The planned radius is 30 ft. Chart note: side capacities require both outrigger beams fully extended; if either beam is not fully extended, use the not-fully-extended column.
1. Calculate the total gross load to be compared with the chart and determine whether the lift is acceptable as set up.
Read the worked answer
Total gross load = 7,200 + 180 + 320 = 7,700 lb. As set up, one outrigger beam is not fully extended, so the chart note requires the not-fully-extended side column. At 30 ft that value is 5,900 lb. 7,700 lb is greater than 5,900 lb, so the lift is not acceptable as set up. The 6,700 lb value at 25 ft also would not help because the planned radius is 30 ft.
2. What are the options to make the lift legal and within the manufacturer's chart?
Read the worked answer
Options:
- Remove or relocate the fence obstruction, fully extend the outrigger beam, re-level, and verify the load is within the fully extended side capacity: 8,200 lb is greater than 7,700 lb, a 500 lb margin of about 6%. Confirm actual radius and quadrant.
- Reposition the crane to lift over the rear, where the 30-ft capacity is 9,800 lb, if the setup and swing path are clear.
- Reduce the load or radius, or use a larger crane. Do not use the rear or fully extended side column unless its requirements are actually met.
3. What assumptions must be verified before using the over-rear column?
Read the worked answer
Verify that the chart is for the actual boom length of 70 ft, the outriggers are fully extended and set on firm ground, the crane is level, the radius is measured at the load center rather than the boom tip, the swing path stays within the rear quadrant, and the gross load includes all rigging and hook block. Also confirm no chart note limits side loads, travel, or wind, and that the LMI is calibrated.