Which old Singers have a walking foot?

[Elennah]

I would like to buy an old Singer for sewing leather. Which models have a walking foot? Our of these, which can use the thickest thread?

[Wishful]

There are quite a few I believe but from what I can tell the singer 111w155 is a popular model 

[Constabulary]

Depends on what you consider as walking foot. Walking foot is not a "firm term" I would say. Though MOST leather workers and dealers consider triple feed (combined top feed, bottom feed and needle feed) as walking foot. However you sometimes even find a plain top feed machine (like Singer 29K) as walking foot machine or even jump foot machines because a foot is moving / jumping  (kind of walking) back and forth. Top + bottom feed machines (w/o needle feed) can be found described as walking foot machines too. So the term "Walking Foot" can be misleading. Even the term compound feed can be misleading - I have seen the term compound feed in needle + bottom feed machine manuals as well as in triple feed machine manuals.

I think triple feed or unison feed describes a machine with 3 feeding mechanisms best. I think unison feed is a JUKI term.

(my 2 cents)

So what comes to my mind are the Singer 111 and Singer 211 (however - both come in a triple feed and needle + bottom feed version - so check the subclasses!!!). The much heavier Singer 144w machines also have unison / triple feed.