As an aside- many vehicle-maintenance-lifts have used a jackscrew,sometimes on one leg only, using cables or chains to send the otherside/corners up.
When you're stood under 1 1/2 tons of metal,unprotected, it concentrates the mind
Invariably, a brass or Phosphor-Bronze nut winds up/down the Acme-thread with the attached carriage conttaining arms/bed.
Floating in that connection is a SECOND nut(often steel) which carries no weight. This can be arranged a short distance from the load-carrier, which, as it's threads wear, closes-up on the secondary, safety nut thus giving an instant visual indication. The safety-nut would not be fit to use regularly but would safely lower the vehicle if the mechanic should witness "jolt" "clonk" as the main nut threads stripped.
I.m amazed that, even back then, an aircraft was certified with no backup safety-nut. must have had more concientious maintenance mechanics back then!