Unit 1a - Basics Of Rigging

Explanation
The weight of the load can be estimated by considering the weight of each timber and multiplying it by the number of timbers. Since the weight of each timber is not given, we cannot determine the exact weight. However, based on the given options, the closest estimate is approximately 10,000lb.

Explanation
If the rigging on the hook is 1/2 inch off center, it means that the load is not evenly distributed. This can cause the load to be imbalanced and put additional strain on one side of the hook. As a result, the load-carrying capacity of the hook is reduced. Since the question asks for the approximate percentage of the load that the hook can carry, the correct answer of 80% suggests that the hook can still bear a significant portion of the load, but not the full amount.

Explanation
The correct answer is 1 1/4. When using a 2 part bridle with a sling angle of 45 degrees, the load on each leg of the bridle is equal to the load being lifted divided by the number of legs. In this case, the load being lifted is 31,000 pounds and there are 2 legs in the bridle. So, the load on each leg would be 31,000 pounds divided by 2, which is 15,500 pounds. To find the rigging size, you need to refer to a rigging chart that provides the safe working load limit for different sizes of rigging. The chart would indicate that a rigging size of 1 1/4 is needed to safely lift a load of 15,500 pounds.

Explanation
The given answer is correct because before using a spreader bar, it is important to have a capacity stamped on the spreader bar to ensure that it can safely handle the load. Additionally, a design drawing showing the correct configuration is necessary to ensure that the spreader bar is used correctly and safely. These two items are essential for the proper and safe use of a spreader bar.

Explanation
The Basic Guidelines include three important points: never exceed the W.L.L., always use a tag line, and never get under the load. These guidelines ensure safety and proper handling of loads. By following these guidelines, the risk of accidents or injuries can be minimized. Therefore, all of the above options are part of the Basic Guidelines.

Explanation
If a wire rope has evidence of heat damage, it is important to take it out of service completely. Heat damage can weaken the wire rope and make it more prone to failure, posing a safety risk. Continuing to use the wire rope could lead to further damage or even accidents. It is crucial to notify a supervisor about the issue and replace the wire rope with a new one to ensure the safety of workers and equipment.

Explanation
Sideload refers to applying a load to the side of a shackle, which can cause the shackle to bend or break. Round pin shackles are not designed to handle sideload, as they have a circular pin that can rotate within the shackle body. Therefore, it is not recommended to sideload a round pin shackle as it can compromise its integrity and lead to failure.

Explanation
Softeners are sometimes used to avoid damaging rigging and/or equipment. This implies that softeners are a type of material or substance that can be applied to the rigging or equipment to cushion or protect them from potential damage. By using softeners, the impact or force exerted on the rigging or equipment can be reduced, preventing any potential harm or wear and tear. This suggests that softeners play a crucial role in maintaining the integrity and longevity of the rigging and equipment.

Explanation
The explanation for the answer being false is that when all legs of the sling are equally spaced around the center of gravity, the load will be evenly distributed among all the slings. Therefore, the sling sizes should be based on the total number of legs, not just four. This ensures that each sling is capable of supporting its share of the load, preventing any imbalance or overload on individual slings.

Explanation
The D to d ratio should be 20:1. This means that the diameter of D is 20 times larger than the diameter of d. This ratio is used to compare the sizes of two different diameters, with D being the larger diameter and d being the smaller diameter.

Explanation
When using a 2 part bridle, having a higher sling angle can increase the lifting capacity. This is because a higher sling angle creates more tension in the sling legs, allowing for a more efficient transfer of the load. With a higher sling angle, the load is distributed more evenly between the sling legs, reducing the stress on each leg and increasing the overall lifting capacity. Therefore, it is better to have a higher sling angle when using a 2 part bridle for increased lifting capacity.

Explanation
The correct answer is "All of the above." This means that all of the mentioned conditions (3 broken wires in one strand of a lay, 6 broken wires in one entire lay, kinking birdcaging or distortion of wire rope) can result in taking the wire out of service. Any of these conditions can compromise the integrity and strength of the wire rope, making it unsafe for further use.

Explanation
Kiewit's policy does not allow for chains to be used for general rigging.