Last March, our packaging line stopped mid-run. The culprit was a small DC motor—a 1/3 hp Leeson—that had finally died after seven years on a label applicator. Operations wanted it fixed by the end of the shift. Finance sent an email asking if this was a good time to 'modernize.' That one question turned a simple swap into a comparison I didn't expect.
I should explain where I sit. I'm the office administrator for a 35-person company. I handle MRO purchasing—roughly $300k a year across nine vendors—and I have to keep operations and finance happy at the same time. I am not a controls engineer. I'm the one who reads the nameplate, calls the distributor, checks the invoice, and then explains why the line is still down.
Here's the thing most sales calls will not tell you: a Leeson DC motor 1/3 hp and a Kollmorgen servo motor are not two versions of the same part. They're two different philosophies. So I'm going to compare them the way I actually did when the clock was running.
Leeson Motor Nameplate vs. Kollmorgen Servo Motor Nameplate
The first thing I did was read the Leeson motor nameplate. If you've ever ordered a Leeson motor, you know the nameplate is a bit of a relief. It lists the catalog number, HP, volts, amps, RPM, duty rating, insulation class, enclosure, and NEMA frame size. NEMA MG 1 requires most of that, but Leeson's printing is actually legible. This one said: 1/3 hp, 90 VDC, 1800 RPM, 56C frame. That's enough to cross-reference to a stock replacement.
The Kollmorgen servo motor nameplate is different. It is not trying to help you order from a catalog; it is trying to identify a configuration. You need the datasheet to translate the model number into a price, and if you don't know the feedback connector pinout, the nameplate may as well be Greek. I found a Kollmorgen servo motor that could do the job, but only after I opened three PDFs. On a different project, I once assumed 'same frame' meant the terminal box would line up. It did not.
Conclusion: If you need a drop-in replacement, the Leeson motor nameplate wins. If you are designing a new motion axis, the Kollmorgen nameplate is fine because you are already doing engineering.
Cost, Lead Time, and the Hidden 'Cheap' Trap
Cost is where my stomach turned. A stock Leeson DC motor 1/3 hp wound up around $260 from the local distributor. Don't hold me to the exact number; distributor pricing moves. The Kollmorgen servo motor that looked like a fit was $1,100 before I added the servo drive, the cable, and the commissioning time. The word 'before' is doing a lot of work.
But I also considered the cheap route. A no-name 1/3 hp DC motor was $140. The upside was obvious. The risk was that it would not match the duty cycle or shaft details. I kept asking myself: is saving $120 worth potentially ruining a $12,000 line? The answer was no. We made that mistake two years earlier with a discount gearmotor—saved $80, then paid $400 in rush labor when it leaked oil. That is the kind of math I do now.
Lead time was another twist. The Leeson DC motor was in stock. The Kollmorgen package had a six-week lead time, and that was before programming. In the real world, a line down for six weeks is not a modernization project; it is a crisis. So for reactive fixes, the Leeson motor wins this dimension too.
Worm Gear Reducer vs. Servo Complexity
Now the mechanical part. The label applicator was not direct drive. It used a worm gear reducer to step down the speed and boost torque. A worm gear reducer is simple, compact, and self-locking at high ratios. That is a big deal for equipment that must hold position without a brake. The tradeoff is efficiency: a worm gear reducer loses more energy as heat than a planetary or servo gearbox at high ratios. For a low-power, low-duty application, though, that is fine.
A Kollmorgen servo motor with a high-performance gearbox would be smoother and more efficient, and it would give us variable speed. But then I would also need a controller, a person who understands tuning, and probably a new guard to meet safety standards. The maintenance crew knows how to diagnose a worm gear reducer: check the oil, feel for play, replace it if backlash gets bad. They do not have time to learn tuning software while the line is down.
Conclusion: The surprise was that the worm gear reducer was not the weak point. The motor was. Replacing the motor with a servo while keeping the worm gear reducer would have added cost, removed one of the reducer's natural advantages, and given us capability we did not need. Servo wins for variable acceleration and precision. A Leeson DC motor with a worm gear reducer wins for fixed speed and self-locking position holding.
What Happened to Pete Jackson Gear Drives? (And Why It Matters)
This is where a geometry question usually comes in. Pete Jackson gear drives were automotive timing gear setups—beefy, loud, and somehow cool. If you hang around maintenance people long enough, someone will ask, 'What happened to Pete Jackson gear drives?' The short honest answer is that I do not know exactly. The original company stopped making them years ago. The rights moved around. Old units show up on auction sites. But you cannot call the original company for support or a replacement part. Some people say the owner retired; some say the line was dropped in the 1990s. I do not want to repeat the rumor as fact.
What I know for sure is the pattern. When a product becomes an orphan, the initial price is not the real price. The real price is the scavenger hunt, the unused spare, the machine that waits for a used part to appear. That same logic applies to motors and reducers. Leeson has a huge installed base and a distributor network. Kollmorgen is still a current product line sold through proper channels, with technical support that answers the phone. Those things matter when a machine has to run again tomorrow.
Conclusion: Do not buy an orphaned component just because it looks like a deal. Ask yourself what happened to Pete Jackson gear drives, and then check whether your replacement part still has a living supply chain.
So Which One Should You Choose?
Choose the Leeson motor if...
...you are replacing a failed Leeson DC motor 1/3 hp on a machine that only needs to run at a set speed. Read the Leeson motor nameplate, verify the frame, check the shaft keyway, and order from an authorized dealer. If the application can use a worm gear reducer for speed reduction and holding torque, you do not need servo complexity.
Choose the Kollmorgen servo motor if...
...you are building a new axis or a retrofit that requires variable motion profiles, tight registration, or frequent direction changes. Budget for the drive, the cables, the commissioning, and the training. The motor is only part of the system. Also make sure your mechanical design does not fight the servo's precision.
And when a supplier offers you a deal on something that used to be supported by a company that no longer exists? Walk away. That is the Pete Jackson gear drives lesson, and I think about it every time I order a replacement motor.
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