Perhaps "easily" needs some definition. I know I used those jacks every time I needed to lift a 240, before I had a floor to put a floor jack on. Instead of just emergency tire changes, my screw jack raised the car for brakes, suspension work, and exhaust system replacements. Then I used them in some nasty weather to help with tire chains. I'd been warned about them, here on the BB, but the point was driven home when one collapsed for me, without too much drama, in the driveway.

The equivalent of what is called the "main nut" in a vise, seems to acquire the most wear. The screw, spreading its wear along its length doesn't show much wear, but like the nut in a vise or the internal threads of spring compressors, it wears unseen and fails under load. I suppose a screw-type scissors jack would fail the same way, eventually.

Parking brakes from Wullerton? (spit)
--
Art Benstein near Baltimore

"If something hasn't broken on your helicopter, it's about to."