In September 2024, a maintenance engineer sent me an email with a subject line that stopped me cold: “What happened to Pete Jackson gear drives?” I typed it into a couple of search engines, found a few forum threads with conflicting answers, and closed the tab. I didn’t know. That should have been the end of it. It wasn’t.
For context: I’m an applications engineer, not a repair tech. I’ve been specifying motors and drives for 11 years, and I’ve personally made enough mistakes to fill a small binder—the expensive kind. The machine in question had a gear drive that was no longer being made, a motor that had been swapped twice, and a load profile that existed only in the head of a retiree. The customer wasn’t asking about a museum piece. He was asking whether he could keep production running. It reminded me of the same conversation I have once a month about motors: just get me the right part. But the part was never the whole problem.
The surface problem: “Which motor do I pick?”
Most inquiries I handle start the same way. An engineer has a part number, a torque figure, or a half-remembered spec. They want to know whether a maxon brushed DC motor will fit their existing mount, or whether a maxon EC motor will fix their brush wear concerns. Sometimes they send over an SG90 servo motor datasheet and ask why a hobby servo can’t hold position under a real load. These are all reasonable questions. They’re also all pointing at the same wrong place.
The motor is not the system. The motor is one component inside a system that includes the gearbox, the controller, the feedback sensor, the wiring, the power supply, the mechanical stiffness, and the operating environment. Comparing torque numbers on a datasheet is the easy part. Let me rephrase: it’s the easy part only if you already know the system.
The deeper problem: a datasheet is a map, not the territory
I’m not saying datasheets are useless. A maxon-motor technical document is better than most; it includes drawings, wire diagrams, and actual test conditions. But every datasheet is still a map. It shows the landscape under specific lab conditions. It doesn’t show what happens when you mount the motor in a warm cabinet, drive it with a cheap PWM controller, and run it at 30% duty cycle for six months.
One of the first serious lessons I learned the hard way came from a simple assumption. I assumed that “same specifications” meant the same performance across two similar motors from two different suppliers. Didn’t verify. Turned out one motor had a slightly different winding resistance and a completely different magnetic design. On paper they looked interchangeable. In production, one ran 14°C hotter than the other. That extra heat shortened brush life, weakened the magnets, and caused intermittent stalls. 400 actuators were already assembled. That mistake cost about $8,000 and a three-week schedule slip—plus the embarrassment of explaining to a customer why their “identical” part wasn’t identical.
I want to say the order was for 400 units, but don’t quote me on that. The embarrassing part is burned in clearly enough.
The SG90 servo motor datasheet problem
The SG90 servo motor datasheet is the extreme case. It’s one of the most common hobby servos on the planet, and the datasheet gives you a weight, a speed, a stall torque at one voltage, and almost nothing else. There’s no current-vs-position curve, no electrical time constant, no thermal impedance, no stiffness figure. For a foam airplane, that’s fine. For anything safety-related, it’s a trap.
Larger servo motors look more professional, but the system problem is the same. A servo motor is only as good as the loop that controls it. If the feedback resolution, controller update rate, and mechanical resonance are not matched, a perfectly good motor will buzz, lag, or overheat. The datasheet won’t tell you that.
Brushed DC and EC motors: two different system decisions
Take a maxon brushed DC motor. It’s simple, inexpensive to control, and great for a lot of fixed-speed or reversible applications. But brushes are a wear item. The brush life depends on current, speed, temperature, and how often you reverse. A brushed motor chosen purely for stall torque can fail in the field long before its rated life.
A maxon EC motor is a different animal. It has no brushes to wear, which is why people often want to upgrade. But it also needs a controller, and the controller changes the system dynamics. You can’t just bolt an EC motor onto a machine built for a brushed motor and expect the same behavior. The commutation is different, the EMI profile is different, and the stiffness of the drive loop is something you have to design, not assume.
This is where the industry has changed. What was a cutting-edge servo system in 2020 is now commodity hardware, but the engineering discipline has to catch up. The fundamentals haven’t changed: load torque, inertia, duty cycle, thermal limits, and the cost of downtime. The execution has transformed.
What getting it wrong actually costs
In my first year (2017), I made the classic newbie error: I sized a motor by holding torque instead of dynamic torque. It was a stepper motor, not a servo, and it held position beautifully at rest. But as soon as the mechanism had to move quickly, the motor stalled. The machine would run for 20 minutes, stall, and reset. 100 parts went into scrap before we caught it. The rework, test time, and lost output ate the entire margin on that job. I still have a sticky note on my monitor that says: Check the curve, not the number.
A few years later, we had a pump application where the customer ran a maxon brushed DC motor continuously, 24/7. I approved the motor because the current rating looked comfortable. I didn’t check the brush life at the actual operating speed. (Should mention: the brush life curve was right there in the catalog. I just didn’t open it.) The customer reported failures after about six months. We replaced the motor under warranty, added a controller that reduced brush wear, and ate the freight. That one cost roughly $1,200 and a long email chain.
The biggest cost isn’t always money. I once watched a team spend a full week arguing about whether to buy a different gearbox. Every member had a favorite supplier. The machine literally could not run until the gearbox question was settled. One engineer finally asked, “What happened to Pete Jackson gear drives?” in frustration—meaning, why does every good option disappear? The real question was: how do we build a machine when component availability changes every year? That’s a risk management problem, not just a mechanical one.
The short version of the fix
I don’t start with the datasheet anymore. I start with the operating profile. What motion is needed, how often, for how many cycles, at what ambient temperature, through what kind of control loop? The datasheet comes after that, not before.
Then I look at the duty cycle and the environment, not just the torque. If a motor is going to run continuously, I check the duty type against the methods in IEC 60034-1. It’s not a thrilling read, but it has saved me from repeating the pump mistake above.
I also look for a manufacturer that publishes more than a motor part number. The supporting documentation matters: dimensional drawings, torque-speed curves at multiple voltages, reducer options, EMC and handling notes, and ideally a product change or end-of-life notice. This is why I keep going back to maxon-motor’s technical pages. They still publish the kind of documentation that lets an engineer answer “what happens if I mount it upside down?” without calling support.
For servo motors, I recommend buying the motor, drive, and feedback as a matched set whenever possible. The integration data is as important as the torque rating. A motor and drive from the same family usually means the loop is already halfway stable.
And I keep a checklist. I’ve been specifying drives for 11 years now, and I’ve personally made and documented 14 significant mistakes, totaling roughly $23,000 in wasted budget. In the past 18 months, our team’s checklist has caught 47 potential errors before they turned into purchase orders. That’s not because we’re smart. It’s because we had the bruises to prove we needed one.
As of January 2025, the “what happened to Pete Jackson gear drives?” question is still a bit of a mystery to me. I could dig into the history if I needed to. But the engineering lesson isn’t about that specific drive. It’s about what happens when a component disappears and no one inside your plant has the data to replace it. The best protection is not brand loyalty. It’s documentation, spare parts, and a system-level view that survives the people who built it.
Five years ago, good practice might have been: pick a reliable motor supplier and hope. In 2025, that’s not enough. The motor, the gearbox, and the controller have to be treated as one system. The basics haven’t changed. But the tools, and the expectations, are not the same.