can you please explain each one
Angry Panda! Google-fu is weak in you! They're hydraulic jacks, just like you'd jack up a car with.
I won't ever type that much info, even though I am familiar with hydraulic lifting jacks (the screw part is just for initial setup), trestles (used when aircraft shoring is required, and engine hoists. My office was in the C-130 ISO inspection dock for years. You should try Google. This is especially true since you seem to be an angry person, as you are not able to do your own work.
