Have had my Automotech AS-7630 scissor lift for well over two years and now couldn't be without it. Little more expensive than some of the clockwork lifts you are looking at but a proper electro hydraulic one raising in safety to a max height of around 4.5 ft. This allows me to view and work on the underneath using an old office chair. I cannot see the point of a lift that still requires you to poke around on your back or with bent knees. It lifts 2700 kgs, it's portable although heavy and with solenoid release safety catch so no air supply required. Only downside is need of scaffold boards to drive my Roadster onto for collapsed clearance.

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Since installing I've added 2.5mm stainless plate's to floor of garage for the wheeled part of scissor's to ride on during extension. Fortuitously at max height my Roadster just clears the chords of roof beams with hood down as can be seen. Note motor trolley with control panel to left.