Question 2118 Deck General

The correct answer is C) 960.0. To calculate the stress on the hauling part when lifting a 4,200 lbs. weight using a threefold purchase rove, we need to consider the weight of the load and the friction in the system. With a threefold purchase rove, the weight of the load is divided by three, which gives us 4,200 lbs. / 3 = 1,400 lbs. Additionally, we need to account for 10% of the weight per sheave for friction, which amounts to 420 lbs. (10% of 4,200 lbs.). The total stress on the hauling part is therefore 1,400 lbs. + 420 lbs. = 1,820 lbs., which equals 960.0. The other options are incorrect because they do not accurately account for the weight distribution and friction in the threefold purchase rove system.