doubt about exercise - threaded connection

[Lucky Luka]

hello to all
I was looking at an exercise on the shingley that I attach a photo.
I have a doubt about the resolution of the exercise.
according to you the formula proposed to find the agent load on the screws is correct? Where does the biron point there should not be 30 degrees?
Thank you.
greetings
♪

 

[Lucky Luka]

or maybe the formula is right but it is wrong to write p1 and p4 being in truth p2 and p3 the most solicited screws?
greetings
♪

 

[meccanicamg]

If the crane works as you drew in pencil, it means that the circular platform will make a pin on the circle all right. the traction load of the screws, due to the tipping of the crane, will have triangular behaviour and in particular zero to the right and maximum to the left, proportionally to the distance. therefore all the screws will be tractioned but those that are worse are not those indicated in the text. There's probably some mistake. These things are solved in different ways but so I do not conceive.
just to understand, you need to see if you consider hard plate or not.