Okay, so manually pumping a jack is not my preferred method!!
After a little digging I found this little gem which will convert any manual hydraulic jack pump to an air operated one.
http://www.gregsmithequipment.com/Ai...t-w-auto-oiler
I then found another lift supplier that sells a RJ 45 jack that lefts 4500# and comes with the air over hydraulic option too. It appears these newer versions do have locking tabs as well. The RJ 45 also has ball bearing wheels instead of just plastic sliders that make it easier to roll the jack to and fro...
I'll keep digging and shopping but thanks for sharing the details on these. I think with enough bells and whistles I can really set a 4 post lift up to do what I want it to do easily.
I need to look more carefully at the commercial 4 post lifts as well, they've got 220v pumps on them which I'm sure will go up faster but they also cost considerably more.