Someone here was keen on the old Simplex jacks.
These ones are nearly 100 years old and lift up to 7.5 tons.
I don't think they are made to take apart easily, and that is not an
easy job. It's like some kind of puzzle, and comes apart and goes back
together only in a certain order.

Here's one before and after I took it apart and cleaned and greased it
and painted it, together with others that I refurbished earlier:
http://i55.tinypic.com/1fahdg.jpg

Here are the parts, over 20 of them:
http://i56.tinypic.com/2dkk3gz.jpg
I've never seen any broken or worn parts, so the design is really
good.
Of course I replaced all the split pins and a couple of other pins.

Getting at this split pin was really tricky. It's hidden behind the
spring arrangement, but by holding the spring back with a wire I
managed to get the split pin out.
http://i51.tinypic.com/11ud8v5.jpg

Inside was 100 years of dirt.
A good clean and grease and they are good for another 100 years!