Divide and Conquer: What Is the Drift Theory and Why It Matters for Your Nordberg Crusher

By Kristina Nordberg, Nordberg Denmark

I've been handling service orders for Nordberg crushers for eight years. I've personally made—and documented—19 significant mistakes, totaling roughly $46,000 in wasted budget. Those mistakes now live in our team's checklist. If you're reading this, you can learn from them without paying my tuition.

If you arrived here by asking 'what is the drift theory?', you're probably not looking for a geology textbook. You're trying to understand why one crusher setup works at one site and fails at another. This article is about that gap.

What is the drift theory?

Geologists used the word drift in the 1800s to describe loose sediment that seemed to have drifted into places where it didn't belong. The drift theory claimed those deposits came from icebergs and floods. Refined over time, it became the glacial theory we use now: moving ice transports and deposits material, leaving behind a messy mixture of clay, sand, gravel, and boulders. The USGS uses glacial drift as the general term for that mixture.

Why does a crusher operator care? Because glacial drift is not a uniform product. It can look like easy gravel in the morning and turn into sticky clay-covered cobbles by lunch. If you treat it like hard quarry rock, you'll make the same mistake I made in my first year: setting a hard-rock CSS, starving the feed, and calling it a feed problem.

The divide that gets ignored

The biggest divide I see in the field isn't between Nordberg and other brands. It's between two very different material sources: blasted hard rock and glacially deposited aggregate. Each one changes how you should set up a cone crusher.

In a hard-rock quarry, you know what the crusher is eating. Blast pattern, primary reduction, gradation—most of it is controlled. In a glacial-drift pit, the feed is the wild card. You can have a 600-mm boulder sitting on clay one hour, then sand the next. That's a completely different set of problems.

Three scenarios I see at Nordberg Denmark

No single Nordberg setup is right for every job. Here are the three situations our team sees most often, and what I'd do for each.

1. Your material is glacial drift or alluvial gravel

Start with the material, not the machine. For pit-run gravel with clay, I'd argue a jaw crusher isn't always the automatic answer. Yes, it handles boulders. But if the feed contains sticky fines, a jaw crusher can clog before the cone ever sees the stone. What works more often than not is a prescreen to pull the fines, a grizzly to separate boulders, and a coarse-bowl cone set to a slightly wider CSS. On the Nordberg side, I like a GP cone for this duty because it gives you more adjustment range when feed quality changes.

The counterintuitive part: don't chase maximum reduction. Chase consistency. A wider CSS will cost you some production on paper, but it will save you from downtime when the feed surprises you.

I've seen a contractor spend two weeks trying to make manufactured sand from a glacial deposit. The problem was never the machine. It was the variability of the feed. The moment they added a scalping screen and a stockpile for blending, the end product became predictable.

2. Your material is blasted hard rock

Here the advice flips. You want tight settings, a maintained feed, and a crusher that holds its reduction ratio. The same GP setup that saved you in a gravel pit will produce too many flat particles in a quarry. A Nordberg HP cone, with its high interparticle crushing force, is usually the better fit. Set the CSS according to the spec, keep the storage bin full, and monitor the power draw.

A quarry manager once told me his HP cone didn't have enough power for a particular ore. The data showed the power draw was high but the feed was falling below the crushing chamber. The real issue was the hopper design, not the motor. That's the kind of divide between theory and practice that a single setup can't solve.

If you find yourself constantly adjusting between these two jobs with the same machine, that's a clue you need two different liner profiles—not a single 'master' setting.

3. You're restarting a machine after winter

The most expensive lesson from my own career involved a Nordberg HP200 we called the Winter Soldier. It looked tough, it had a huge safety factor, and the previous owner swore it ran perfectly before storage. It sat outside through a cold wet Danish autumn. On restart day, the oil sight glass looked clean; the pressure gauge looked acceptable. I decided we didn't need the $70 oil heater that was sitting in the service van.

Forty minutes after start, the pressure spiked, overpressure dumped, the bearing temperature alarm went off, and we had a seized main shaft. Water contaminated the lube oil, and it only revealed itself as a visible emulsion after the oil circulated. The outcome? A $14,200 repair and two weeks of downtime in March—exactly when we needed the plant.

The conventional wisdom says check oil temperature before you start. I've known that for years. I do not always follow it when a customer project is running late. That's the honest reason why I made the mistake.

Now, after any winter storage, we have a three-step restart rule:

1. Drain from the bottom of the lube tank and check for water/emulsion—even if the sight glass looks fine.
2. Heat the oil to the minimum temperature stated in the crusher manual, measured at the pump outlet, not the tank.
3. Run the lubrication system through a full pre-lube cycle and watch the pressure trend for at least five minutes before starting the crusher.

There's something satisfying about a machine that starts first time after a proper warm-up. The best part: your surprise call at 7 a.m. is about aggregate, not an oil alarm.

Never expected the Winter Soldier nickname to become a project management inside joke. Turns out the real enemy wasn't the cold. It was the assumption that a machine that sat for months behaves like one that ran yesterday.

How do you know which scenario applies to you?

Ask yourself these four questions before changing anything:

• Is my feed naturally deposited in layers of soil, clay, and rock, or is it blasted from a solid rock face?
• Does my current crusher setting produce the right shape consistently across the whole shift?
• Did this machine sit unused for more than two weeks? More important, has it been through freeze-thaw weather?
• When was the last time I checked the lube oil from the tank drain, not just the sight glass?

If you're processing glacial deposit from a pit, scenario 1 applies. If you're blasting hard quarry rock, scenario 2. If the machine has cold weather or storage time in its history, follow scenario 3 even if it cranks right up.

What I'd do differently if I started over

The drift theory taught me to respect the history of the material. A Nordberg crusher is a powerful, beautifully engineered machine—but it's not a universal translator. It takes whatever you feed it, and it gives you exactly what the setup allows.

So when someone asks me 'what is the drift theory?' I give them the geology answer. Then I tell them the same lesson in maintenance terms: drift is what happens when you ignore the difference between where material came from and where it's supposed to go. Learn to read the deposit. Respect the cold. The crusher will do the rest.

Kristina Nordberg is a service engineer at Nordberg Denmark. The views here are her own, based on field experience from 2017 to the present.