Interroll 138i vs Conventional Conveyor Drives: What 6 Years of Procurement Data Told Me

Six years ago, I inherited the procurement budget for a mid-sized logistics automation company. About $1.1 million a year, mostly conveyor components. Since then, I've processed roughly 200 orders for drives, rollers, and motors — and documented every one in our cost tracking system.

I thought I understood the cost landscape pretty well. Then I ran a full TCO comparison between Interroll 138i drum motors and conventional gear motor setups, across four conveyor retrofits between March 2024 and February 2025. The results changed how I buy. This is that comparison.

Why I Compared the Interroll 138i to Conventional Drives

The question engineers usually ask is: "Why would I spend more on a 138i when a standard motor-and-gearbox package costs less?"

That's the wrong question. The right one: "What does each option cost over its full lifecycle?"

Because a bare gear motor isn't a complete drive. You still need a motor, a gearbox, chain, sprockets, mounting brackets, guarding, and labor to assemble all of it. The 138i is one component doing the whole job. Comparing their sticker prices without accounting for that is comparing apples to oranges.

So here's how I set up the comparison — four dimensions:

1. Total purchase price, including installation labor
2. Maintenance hours and downtime costs
3. Supply chain lead times and predictability
4. Energy consumption in real operation

Dimension 1: Purchase Price vs. Installation Cost

Let's get the obvious one out of the way. The Interroll 138i costs more per unit. In the quotes we received, a conventional motor, gearbox, chain, and sprocket package ran roughly 22% cheaper on paper. In the first retrofit proposal, I almost approved it. It was a clean line-item saving, and my quarterly budget report loved me for it.

Then installation started.

Conventional setups needed motor rails, mounting brackets, chain alignment from a skilled fitter, guarding for exposed rotating parts, and separate electrical work for the starter and overload protection. The 138i slides into the conveyor frame, one cable connection, done.

The numbers were stark. Our installers averaged four hours per conventional drive, versus about 45 minutes per 138i. At shop rates, that's roughly $200 in labor savings per drive — every drive. On a twelve-drive section, the "cheaper" system cost us $1,140 more in installation labor before it ever turned a roller. I still have those timesheets, and I still wince when I look at them.

Dimension 2: Maintenance Hours and the Real Cost of Downtime

This is where my conventional wisdom got flipped.

Everything I'd read in trade publications said drum motors were harder to service. A conventional gearbox, the argument goes, can be rebuilt by any competent mechanic. In practice, I found the opposite.

Over six years of maintenance tickets, conventional chain-and-sprocket drives generated 3.4x more maintenance hours per drive than the drum motors. Chains stretch. Sprockets wear. Gearboxes weep oil. Each issue is small. Together, they eat your maintenance budget one work order at a time.

And downtime? That's where the real money hides. In Q4 2024, one of our conventional drives failed on a Friday afternoon. The line stopped for six hours. That single failure cost us $3,200 in late penalties from a customer with an unmovable delivery window.

Not ideal. But worse than the cost was the uncertainty. We didn't know if the replacement gearbox would ship in two days or two weeks. The vendor said "probably by Wednesday." I'd learned by then that "probably" means nothing.

Why does this matter? Because with the standardized Interroll platform, we got a confirmed lead time. No probably. No we'll see. A date on the quotation, and the part arrived on that date.

Look, I'm not saying conventional drives fail constantly. I'm saying they fail with less predictability. And when your operation runs on schedules, unpredictability is the most expensive thing you can buy.

When I say certainty has value, I do not mean "nice to have." I mean measurable, invoiceable dollars.

Dimension 3: Lead Times and the Interroll Nordic Difference

The supply chain angle became obvious when we mapped our vendor list.

We're based in Sweden, serving the Nordic market. For conventional motors, we dealt with three different suppliers — one motor from Poland, another from Italy, another from Germany. Each had its own quote process, its own shipping quirks, its own excuses. Each shipment needed its own coordination, and the lead times varied wildly.

Interroll Nordic gave us one point of contact and local stock of the 138i platform. Spare parts arrived in two to three days, not two to three weeks.

My experience is based on roughly 200 mid-range orders with European suppliers. If you're sourcing in a region without local Interroll representation, your lead time experience might differ significantly. But in the Nordics, the difference was consistent across every order we placed.

That local stock is what I'd call a time certainty premium. The unit cost is higher. The calendar cost is predictable. For a company with production deadlines, predictability has a line item attached to it.

Dimension 4: Energy Consumption

Honestly, this was the most surprising result of the whole comparison. I expected the 138i to use less energy — drum motors usually do. But I didn't expect the gap to be that wide.

Conventional gear motors are efficient at full load. The problem is they rarely run at full load. They get oversized "just in case," and efficiency suffers. The 138i's motor is matched to the roller's actual duty, so it runs closer to its design point.

Across our four retrofitted sections, we recorded a 12–18% drop in measured energy use compared to the legacy gear motor drives. At the electricity rates we were paying in February 2025, that's about $840 per section per year. Doesn't sound huge until you multiply it across fifty drives.

Which One Should You Actually Buy?

If your operation is simple, your runs are short, and a four-hour failure won't wreck your week — the conventional route still works. It's a legitimate choice. I won't tell you otherwise.

But if you run continuous shifts, have delivery commitments, or serve customers who notice a late shipment immediately, the Interroll 138i earns its premium. I've paid both kinds of invoices. I know which one I resent.

Here's my rule of thumb:

• Choose conventional drives when capital budget is the binding constraint, the application is low-duty, and downtime doesn't trigger penalties.
• Choose the Interroll 138i when uptime matters, the operation is continuous, or you've already been burned by an unpredictable parts pipeline.

One more thing: we now have a procurement policy requiring three quotes and a TCO spreadsheet for every drive order. I built that calculator after getting burned on hidden installation costs twice. It's saved us more than I can count.

A note on pricing: quotes I received for 138i units ranged from roughly €510 to €880 depending on power rating, as of March 2025. Verify current pricing at interroll.com — the market moves, and I'm not the final word on rates.

There's something satisfying about a conveyor line that just runs. After all the vendor headaches and spreadsheet battles, watching a standardized platform get through two consecutive production peaks with no unscheduled downtime — that's the payoff.

Do the full TCO before you choose. Don't just compare purchase prices. Because in my experience, the money you save on the quote has a way of showing up later in the hours.