Buyer's FAQ: Martin Sprocket & Gear, AC Motor Speed Control, and Linear Actuator Failures

I'm the office administrator who handles all purchasing for our 150-person manufacturing plant—roughly 60–80 orders a year across eight vendors, reporting to both operations and finance. Sprockets, motors, actuators, timing belts for the fleet vans, you name it. These are the questions I search for most, and the answers I learned the hard way.

What does Martin Sprocket & Gear actually make?

Martin Sprocket & Gear (usually just "Martin" in the trade) has manufactured power transmission components since 1951. Their main product lines are roller chain sprockets, gears (spur, bevel, worm), mounted bearings, conveyor components, and couplings. If a conveyor or a machine drive uses it, there's a good chance Martin makes a version of it.

From a buyer's perspective, the value isn't just the part itself—it's the consistency. Sprocket bore sizes, keyway specs, and dimensions are standardized across their catalog, so you can order replacements without having to reverse-engineer anything. And since they stock a huge range at US locations, lead times are predictable.

Is the Martin Sprocket & Gear catalog worth downloading?

Yes. I wish I'd started using it when I took over purchasing in 2020. The Martin Sprocket & Gear catalog is a large PDF organized by product family, so when I'm sourcing a chain drive, I can find the sprockets, chain, and bushing specs in one place instead of chasing three different suppliers.

Everyone told me to check the chain pitch before ordering sprockets. I didn't listen—once. We ordered a 40-pitch sprocket for a conveyor that ran 50-pitch chain. That $90 part ended up costing us around $350 in restocking fees and next-day freight while the maintenance crew stood around waiting for the right one.

The catalog also includes engineering data: bore sizes, maximum RPMs, and dimensional drawings. That alone saves me a call to technical support every time I need a spec.

What's the deal with Martin Sprocket Arlington?

The Martin Sprocket Arlington facility is one of their major manufacturing and distribution locations. We're close enough that ordering from Arlington cuts days off our standard lead time compared to a non-stocking distributor.

Honestly, I've never toured the facility, so I can't verify exactly what's manufactured on-site versus stocked there (as of early 2025, at least). If that distinction matters for your project, I'd call them directly and ask.

What should I know about AC motor speed control?

If you need to control the speed of an AC motor, you're almost certainly looking at a variable frequency drive (VFD). It controls speed by varying the frequency of the power supplied to the motor. Feed 60 Hz to an 1800 RPM motor and it runs at 1800 RPM; drop the frequency to 30 Hz and it runs at roughly 900 RPM.

Three lessons I've learned buying these:

1. Match the drive to the motor's full-load amps. We bought a discounted 1 HP drive for a 1.5 HP motor once. It tripped out under load every time. The 2 HP drive we swapped in fixed it immediately.
2. Check whether the motor is inverter-rated. Standard motors can work with VFDs, but the cooling and insulation behavior changes at variable speeds. Not every motor is suitable for continuous VFD duty.
3. A VFD isn't plug-and-play. It needs to be programmed with the motor's nameplate parameters. Skipping that step causes weird behavior that looks like equipment failure but isn't.

From a budget standpoint: a properly sized VFD costs a bit more upfront, but a failed undersized drive plus the downtime to swap it costs far more.

Are Aisin timing belt kits worth using?

For our service fleet, yes. Aisin is a major Japanese OEM supplier—they've made original parts for automakers for decades. That history doesn't guarantee every application, but it's a stronger starting point than a brand I've never heard of.

The kits we've used include the belt, tensioner, and idler pulleys. One rule I now follow after a 2023 mistake: verify the engine code, not just the year/make/model. The same car can have two engine options, and we ordered the wrong kit once by relying on the vehicle's year alone. The restocking process took a week.

I can't quote you specific reliability statistics for Aisin kits—that's outside what I do as a buyer. What I can say is, in five years of ordering them, we haven't seen a premature failure.

What happens when a linear actuator fails?

We use linear actuators for gates, diverters, and a few packaging-line positions. When one fails, I've seen three main modes:

• Complete stop. The motor burns out, a limit switch dies, or a wire breaks. The load just stays where it is.
• Jam or stall. The motor hums or buzzes, but the lead screw or gearbox has stripped internally. No movement.
• Drift. The actuator creeps out of its set position when it's supposed to hold. This is the dangerous one—it usually means the brake is worn or the lead screw is failing.

What actually happens to your equipment depends on what the actuator is doing. If it's part of a safety interlock, the machine won't start. If it's holding a heavy gate or platform up, you've got an unplanned movement that's a safety hazard.

That's why I'm willing to pay more for an actuator with a mechanical brake and a proper limit switch. We tested a cheaper unbranded unit once and it couldn't hold position under load. The savings weren't worth it.

If you're troubleshooting: check the limit switches first, then the voltage at the motor terminals. Sounds simple, but I once spent an afternoon chasing an "intermittent actuator failure"—turned out to be a loose wire on the terminal block. A $0.10 fix.