Leave the eccentric at the 1.000-inch mark for a starting point, but you’ll want to try various lengths and positions of toggling points. That’s how you’ll achieve the action of the machine.

For example, if you want to close this machine down to a 1.000-inch discharge setting, you’ll want it to toggle in such a manner as to provide an open position setting of 2.000 inches. Most crushers of this feed opening and approximate width have jaws slightly over 24.000 inches long. Toggle the machine in such a manner that the discharge match points align somewhere between the open and closed side settings, perpendicular to the back of the moving jaw. If you’re building something from scratch, you’ll have a little trial and error in your preliminary modeling.

Although the part is not of Columbia Steel’s manufacture, it is still a viable part. We make that bowl liner and still have a few users of that profile.

That bowl liner is classified as a “medium crushing liner -- long conventional”. It’s most commonly used with mantle OEM # 5013-9268. The optimum sizing range for this liner set is reducing 3.000-inch top size material with a blend of 2.000-inch x 1.000-inch mean size at .250-inch to .500-inch discharge setting.

The only odd lot consideration of the use of this part is that it fits “fine” bowl frames only. The majority of Symons crusher bowl frames are of the “coarse” variety. So those surplus liners you got a hold of will have a more limited range of use, simply due to what bowl frame they fit.

We’ve made available several different subsequent profiles for 7-foot Symons S.H. cones that are designed to work in that sizing range, and which react differently to different materials and offer more extended life spans than the profile we’re discussing here. However, the short answer to your question is: yes, that is still a viable liner profile, although not optimum for every application -- and take care with which bowl frame it fits.

A review of our master parts catalog shows there are nearly 50 models of crushers in that approximate size range, with few likely sharing a common mainshaft eccentric stroke. Each manufacturer of these machines will incorporate their own eccentric geometry, relative to the depth of their crushing chamber, toggle position and length, power and speed chosen to run the crusher, and the overall stoutness of the crusher’s construction. With the variables that can be incorporated into a jaw crusher, we don’t believe a “standard” for eccentricity exists, except within a given manufacturers own standards. That is -- crusher manufacturers Cedarapids and Kue-Ken will have different views than Metso.

You’ve described a rather small crusher. Normal callout for crusher sizing is that the first number stands for the feed opening and the second number calls out the width. The smaller number generally comes first and identifies the feed opening, although several manufacturer and model exceptions exist. If you’re dealing with a specific model crusher, you’d best contact the manufacturer for their prescribed eccentric specifications.

To address your question as asked -- if one were to build a crusher with a 12.000-inch feed opening and a 7.000-inch width (not typical order of dimensions), the depth should be 30.000-inches minimum (creating an odd sized crusher), with an eccentric of 1.000-inch (2.000-inch stroke). That’s where we’d start with what we’ve seen. A good deal of the “action” of the crusher can be altered by the length and position of the toggle plate, relative to the chosen stroke.

There are a lot of variables that go into the design of a jaw crusher, and calling for a standard stroke for given sizes isn’t something that can be arrived at. Further discussion of your question would be in order to offer a more specific and relative answer.

Though perhaps not your intent, there are two subjects in this inquiry.

Let's start by noting that the manganese element content is relative to the carbon content. We've found a considerable inter-relationship between manganese and carbon content of wear steel, especially as it applies to fatigue resistance of crusher parts.

Regarding manganese content, we've been able to amass some useful generalizations regarding application of high alloy manganese. It goes like this:

The best use of high alloy manganese comes when the material being crushed is at a mid-point between low and high compressive strength values, along with low and high silica contents. The low end of that scale is 20k p.s.i. compressive strength and .2 silica content; the high end of that scale is 80k p.s.i. compressive strength and .8 silica content. This allows maximum advantage for use of high alloy manganese with materials at 50k p.s.i. with a .5 silica content. Any deviation in either value, in either direction, alters the degree of gain or loss in the successful application of the high alloy material.

We drew those conclusions from a customer site where we doubled the service life of jaw dies over conventional 12% manganese. At the low end of the scale, low silica and strength values don't allow the manganese to work harden enough to improve wear rates. The high end values will overcome the manganese steel's ability to resist fatigue and fail before they are fully expended.

To reply to your question as presented -- the more abrasive the material being crushed, the higher carbon levels are in order, such as those in high hardness carbon steels, or high hardness irons. The crushing of very high compressive strength materials is best suited to conventional 12% manganese content levels with low carbon values of under 1.0. This concurs with the original principle of crushed materials somewhere between those extremes optimizes the application of high manganese and carbon wear alloys.

The development of better wearing manganese is an evolutionary process. In another 20 years, there'll be a different set of numbers in ratio that optimize crusher wear materials.