It's a flanged bearing at the top. The threaded rod is proper Acme leadscrew.Looks the part! Is that a bearing carrier you’ve used for the top end of the threaded rod?
Did you make this off plan or is it to your own design? I’ll be needing one myself in due course once the garage is cleared to get the car back in there!
The load is almost directly down through the upright, there is no bending moment applied to it. For the wheels to kick out it will require some fairly catastrophic material failure. Which I am not expectinglooks good :-)
I'd add angled supports to the bottom of the upright tho... one off to each side and one forwards
or... the leg sticking out under the car.. you could have a long length slide inside that, or along the edge of it, under the car and to the other leg? (just bolt them on?) - stops the weight of the car pulling/bending on the upright and wanting to put the wheels out/away from the car?
The load is almost directly down through the upright
If there were very little load directly down through the beam there would be no reaction or B.M.I don't see how you get that. There appears to be little load directly down through the upright; it's almost entirely a bending moment or have I missed something?