Just as an aside to buying trolley jacks, if you can, buy one with steel wheels. If you can't afford one with steel wheels, make sure you check the plastic wheels prior to use, (nylon wheels are usually ok though), and when you put them away try not to drop them on the floor or throw them under the bench. The hard plastic can crack or shatter.
We do a lot of product testing and I have personally had trolley jack wheels fail under load.
It's usually the rear, swivel wheels that fail. Another failure point is the rear wheel mounts. They are usually mounted onto 2-3mm thick formed steel.
You rarely have trouble with the hydraulics, but you need to check the jack mounts and wheels.
Many, (if not all) of these jacks are mass produced and although the manufacturers tell you they are tested, they only test small production samples.
Same with axle stands, most are fabricated from 2-3mm steel strip. The weak points on these are the welds holding them together. Again, don't throw them around as it's very easy to crack a weld, especially if proper weld prep hasn't been followed during manufacture.
Stay safe