If you handle purchasing for any kind of operation that uses electric motors, here's the advice I'd give before you call a supplier: get the LEESON motor catalog and the LEESON 3 phase motor wiring diagram for the exact model you're considering. That combination has saved me from at least a dozen costly mistakes since I took over purchasing in 2020. I'm an office administrator at a small manufacturing plant, and I manage roughly $180,000 in annual MRO spending across eight vendors. Not a huge operation, but big enough that one downtime incident gets noticed. And in my experience, most downtime comes from people skipping the details.
People assume that the cheapest quote means the most efficient purchase. The reality is that a motor that doesn't fit or gets wired wrong costs ten times more than any price difference. I know because I've lived it.
Why the LEESON Motor Catalog Is Your First Stop
Before you compare prices, open the LEESON motor catalog PDF. The catalog lists frame sizes, shaft dimensions, voltage, current, and even the weight of each motor. For a 3 phase induction motor, that spec sheet is the difference between a clean swap and a field modification nobody budgeted for.
Last year we needed a 1.5 hp, 3 phase induction motor to replace one that burned out. A sales rep insisted the 'equivalent' from another brand would fit. But the LEESON catalog showed our original motor had a 5/8" shaft, while the substitute had a 7/8" shaft. Installing it would've required a new coupling, a new bell housing, and three days of fabrication. We caught it because the catalog was in front of us.
If you're wondering whether your old LEESON motor can be replaced by a newer model, the catalog usually includes a cross-reference guide. That's how I've found direct replacements for obscure 115V motors without having to call tech support. The PDF is searchable, too, which saves time when you're in a hurry.
How to Read a LEESON 3 Phase Motor Wiring Diagram Without Panicking
The wiring diagram is the second document I always pull. It's tempting to think that all single-speed 3 phase motors wire the same way. But they don't. Different voltage configurations affect how you connect leads. LEESON includes both low and high voltage connections in the same diagram, usually for 230V and 460V. If your electrician assumes, you risk a wrong phase sequence or even a short. And that's how you smoke a $3,000 motor.
The most frustrating part: this is completely avoidable. You'd think with standards, all motors would be identical. Not true. Having the LEESON-specific diagram is the only way to be sure. Our maintenance team now knows to ask for it before touching any replacement. The diagram on the motor nameplate often only shows the connection for the voltage listed on the machine; the catalog shows all available wiring options. I've learned to check both.
"If you can't verify the wiring, you're buying someone else's guess."
The Truth About Servo Motor Repair
Servo motors are a different animal. They have encoders, feedback loops, and magnets that can lose alignment. If you're tempted to save money with a generic repair shop, read this first. I've seen quotes for 'repaired' servo motors that cost less than half of a new one, but they came with zero test data. Per FTC guidelines, service providers should substantiate their claims. When a repair shop can't show you test run data or doesn't follow the manufacturer's specifications, treat it as a red flag.
In our case, that 'half-price repair' failed within a month. We sent the next failed servo to the original manufacturer's authorized service center. It cost more, but it came with a warranty and documentation. That's the kind of documentation that protects your reputation with your own customers. One more thing—when a repair quote is suspiciously low, ask if they've tested it under load. Some shops just clean and re-lubricate. If they can't provide a test report, assume it's not been done.
Which Gear Is Most Likely to Use a Spur Gear? (Short Answer)
The short answer: a compact, cost-sensitive gearmotor most likely uses a spur gear. Spur gears have straight teeth and mesh on parallel shafts. They're simple, efficient at moderate speeds, and cheap to make. So when you see a small LEESON gearmotor with a low price tag, expect a spur gear inside. If you need quieter operation or higher torque, you'd likely move up to a helical gear. But for many straightforward conveyor or packaging applications, spur gears are workable.
You might also find spur gears in some right-angle gear reducers, but that's less common. For worm gear reducers, you're looking at a different mechanism entirely. The question isn't really about brand—it's about application. If you're replacing a gearmotor and aren't sure what's inside, the catalog will tell you the gear type and ratio. That's another reason to keep a copy handy.
When to Ignore This Advice
Honestly, there are times when you can skip all this. If you have a trusted LEESON distributor who asks the right questions, they'll send the correct motor and wiring diagram with it. And if a servo motor still under warranty fails, don't repair it—just send it back. Also, if your application runs in extreme temperatures or has custom voltage requirements, the standard catalog might not be enough. The catalog is a starting point, not the final answer for every situation.
If you're just replacing a motor that's identical to the old one, you may not need the diagram. But the moment conditions change—different voltage, different enclosure, different physical size—that's when the catalog pays for itself. It's a lesson I learned the hard way, and now I don't order anything without pulling the PDF first.
Ultimately, I'd rather look at a wiring diagram than a repair bill. Not ideal, but workable.
Discuss this motor note