Hi Kurt,
The ones with no scale on the far side (Pile Side - 'cause manufacturers would have designated steel blocks for each model,with pins sticking up - on which they'd PILE the various components for assembly .... starting with the far side liner with handle scales face down). Modern knives with no far side scale are called "Frame Lock". They use heavier material for the locking bar (it's still a liner lock in all aspects), but they use a heavier piece (often Titanium) and then slice the leaf spring area the same. To get it to bend, they use a technique which would have any engineer or bowyer cringe. They mill across the width of the spring bar, at the back; and let it flex in one spot. The opposite of "Stacking", where a spring is tapered. It works because the area only flexes/moves a very tiny amount. But it still makes me cringe.
There are also all manner of ball bearing rigs for the pivot area. Loose ball or caged ball. One bearing race, two bearing race, or no bearing race. On some, the bearing ball RIDE on the axle thru bolt and the ball are captured on a shelf between the axle and shelf wall. In some, the blade tang is milled for the ball race, and the outer side of the ball runs on the liner material.
Knowing me .... what did I do? Right. What I saw as the best engineered. The blade tang is milled with a bearing race on each side. AND, I milled seperate outer TOOL STEEL bearing race. The outer race are let thru the liner material. So; the hardened ball, ride in the hardened integral race of the blade tang, and are topped by the hardened tool steel race in the Liners. Only thing I don't make are the ball. (BTW - the word BALL is singular OR plural depending upon usage. And it avoids lots of jokes if you don't add an S.
My Knife has scales both sides. The liner with the leaf spring is tool steel. This is NOT necessary on most liner locks. Not unless you are having a beast or a real work knife. Michael Walker invented the Liner Lock. I knew him pretty well back then. I have worked in his shop with He and his wife Patricia. We went out by the land fill. Found a length of steel cable. I welded that up in his electric heat treat oven. The borax flux melted the lining and we burned out an element trying to maintain 2,300F. But it welded clean. Michael made the knife. I carved ancient ivory primitive man inlays. Patricia anodized it. There was a Harmonic Convergence taking place at the time. The Desert Mystic People were all nuts over the first five planets aligning in a linear pattern from the Sun. We inlaid semi-Precious stones (in the blade from bolster outward) matching color and relative size of Sun, Mercury, Venus, Earth, Mars, and Jupiter. I also did some Titanium carving (and sneaked in a tiny USS ENTERPRISE). Haha. I was out there for the Dallas show that year. I went to his home after the show. We worked for a week on the knife. I made one phone call. Sold. Oh btw .... back to liner locks .... Michael's springs were not hardened. They were usually Titanium. And, he never used any "Dead Animal Parts" - his quote. Haha.
Well, see what you get when you talk to me .... haha.
Gary