Keep in mind that the vehicle above probably only weighs 6,000 lbs. You're not going to put 27,000 lbs of force on the tree when winching with the triple-line pull in that scenario.
Indeed those numbers are at each connection point given a maximum pull of a 9k winch at the first layer. If the truck requires 6,000 lbf and not 27k to get unstuck then all the forces are reduced relatively but until you do an analysis you don't know.Keep in mind that the vehicle above probably only weighs 6,000 lbs. You're not going to put 27,000 lbs of force on the tree when winching with the triple-line pull in that scenario.
In the 9,000 lb pull above, single line would be expected to see 9,000, double to see 4,500 each, and triple to see 3,000 each. The tree should always see 9,000. But the winch sees 9,000, 4,500, and 3,000 respectively and the vehicle moving speed declines by 1/2, then 1/3.If you want to halve the work the winch is doing put the sheave on vehicle B in your scenario and connect the winch line back to the vehicle with the winch.
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Notice though that the winch will still be capable of the full amount of force and the thing to watch is the point with the block in this case could actually see 2x that, so you need to do stuck analysis and consider safety, such as the recovery point strength and the need to use a bridle.