What is the main purpose of the overhaul ball (headache ball) on a single-part whipline?
- Its weight adds to the crane's rated capacity when on the whipline
- It stops the hook from being drawn into the boom tip
- Its weight keeps the line taut and pulls it down when unloaded
- It measures the load on the line for the operator
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C. Its weight keeps the line taut and pulls it down when unloaded
With no load on the hook, the ball's weight overcomes friction and the weight of rope on the drum side so the line pays out and stays seated in the sheaves. Its weight is a deduction from capacity, never an addition.
Reference: Mobile crane components
A solid concrete block is 6 ft long, 4 ft wide and 2 ft high. Concrete weighs 150 lb per cubic foot. What does the block weigh?
Answer in lb.
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7200 lb
Volume = 6 × 4 × 2 = 48 ft³. Weight = 48 × 150 = 7,200 lb.
Reference: Load weight calculation: volume x unit weight
Under OSHA's Table A, what is the minimum clearance from a power line energised at up to 50 kV?
- 10 feet
- 4 feet
- 15 feet
- 20 feet
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A. 10 feet
Table A sets 10 feet for lines up to 50 kV, rising in steps for higher voltages. Twenty feet is the distance that triggers the power line precautions when the voltage has not been established, and 15 feet is the Table A value for over 50 kV up to 200 kV.
Reference: 29 CFR 1926.1408, Table A
What is a main drawback of lifting a load with one sling in a single vertical hitch?
- The sling loses about half of its rated capacity
- The load is free to rotate and hard to control
- The sling tightens and crushes the load
- The load angle factor rises above 2.0
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B. The load is free to rotate and hard to control
A single vertical leg gives no resistance to spinning, and rotation can also unlay a wire rope sling. The sling keeps its full vertical rating in this hitch, so loss of capacity is not the problem; control is.
Reference: Rigging principles: vertical hitch
The signalperson extends an arm horizontally to the side with the fingers closed and the thumb pointing up. What is the signal?
- Raise the boom
- Hoist the load
- Extend the boom
- Swing the boom
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A. Raise the boom
Arm out to the side, thumb up, fingers closed means raise the boom (boom up). Hoist uses a raised forearm with the index finger circling. Extend the boom is a two-hand signal given at waist level.
Reference: 29 CFR 1926 Subpart CC, Appendix A (Standard Hand Signals)