Rated lifting capacities for crawler-mounted and pneumatic-tired cranes, expressed as a percentage of tipping load at a given radius, are respectively_________________?
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Answer: D. 75 and 83
Explanation
Rated lifting capacities are regulated as specific percentages of the crane tipping load. Crawler-mounted cranes use seventy-five percent due to crawler stability characteristics. Pneumatic-tired cranes use eighty-three percent because outriggers provide enhanced stabilization. Crane stability is governed by overturning moments balanced against machine weight and outriggers. Tipping load represents the weight that causes the crane to tip over at a given radius. Safety margins protect against dynamic wind loads and sudden load swings during lifting.
Rigging engineers consult crane load charts to ensure safe lifts on construction sites. Crawler cranes operate without outriggers in motion, requiring conservative capacity ratings. Pneumatic-tired cranes deploy outriggers to increase stability and lift heavier loads safely. Option A reverses the required capacity percentages for crawler and pneumatic-tired cranes. Option B provides incorrect percentage figures that do not match standard crane regulations. Option C lists inaccurate safety factor percentages for mobile crane stability ratings.
- Subject
- Engineering
- Category
- Civil Engineering
- Topic
- —
- Difficulty
- medium
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