Technical references for selecting, testing, and troubleshooting small gearmotors.
Use the articles for design decisions, the calculators for first-pass sizing, and the test material to define what must be proven before release.
- Articles published
- 12
- Guides published
- 0
- Library last reviewed
Changing a motor that is already in production
A part is obsolete, a source has moved, or a supplier has changed something. What has to be proven again, and what does not.
-
Cross-referencing a motor without requalifying the mechanism
Which parts of a motor change can be closed by comparing data, and which parts force the mechanism back onto a test bench?
-
How to qualify a second-source motor
What evidence turns a second-source candidate into a released part, and how many units have to be tested before the result means anything?
Specifying and sizing a new one
What belongs in the document, and which published numbers are capabilities rather than limits.
-
What to put in a compact motor specification
What has to appear in a motor specification so that two suppliers quoting it build the same thing, and a field failure can be attributed to a cause?
-
Why stall torque specifications are routinely misused
Why is the stall torque on a data sheet almost never a usable design number, and what should be used in its place?
Where noise, backlash and current draw come from
Mechanical behavior traced back to the geometry and the manufacturing operation that produced it.
-
Why apparently identical gears have different noise profiles
Two gears made to the same drawing, from the same material, with the same tooth count. Why does one train whine and the other not?
-
How center distance and gear quality affect current draw
Why does one gearmotor from a lot draw noticeably more no-load current than the next, when both pass every dimensional check on the drawing?
-
How axial endplay creates intermittent noise
Why does a motor tick, knock or clatter only on reversals, only at certain speeds, or only in one mounting orientation, when nothing about the gear mesh has changed?
-
How pinion runout propagates through a geartrain
A pinion is 15 µm eccentric relative to its bearing. What does the output shaft actually see, and which stage's runout matters for position and which for noise?
What sets life, and how to test for it
Brushes, lubricant and duty cycle, and the counters that actually accumulate wear.
-
Why grease selection changes noise, efficiency and life
What does the lubricant in a small gearhead actually decide, and why does changing it change the measured performance of a motor that has not otherwise been touched?
-
Precious metal versus carbon brushes in real duty cycles
Which brush system belongs in a given application, and why does the answer depend more on the duty cycle and the supply voltage than on the torque?
-
How to estimate life from an application duty cycle
The mechanism runs a repeating cycle. How do you turn that cycle into a statement about how long the motor will last, and what part of that statement can only come from a test?
Diagnosing a failure
Reading the evidence a failed unit carries, and separating a misapplication from a defect.
-
What happens during a locked-rotor event
A mechanism jams and the motor stops turning with power still applied. What fails, in what order, and how long is there before something is damaged?
Library status
The library grows from reviewed engineering work. Use the published articles today; future topics remain clearly identified as planned.
12 articles are published and reviewed. There are no published guides, videos, webinars or case studies yet. Those pages exist, say what they will contain, and route you to the material that does exist.
Queued next
- Hobbing fine-pitch gears, and what the process controls
- Powdered-metal gear tradeoffs against cut and molded gears
- Why prototype units and production units behave differently
- Converting an AC synchronous mechanism to DC or brushless
- Winding selection: choosing a voltage and a torque constant
- Lubrication and test methods used on the bench