Martin Sprocket & Gear: An Engineer's FAQ on Ordering Parts Without Breaking Things

Eight years ago, I thought a sprocket and a gear were basically the same thing. They're not. Fast forward: I handle component orders for a conveyor integrator, and I've made twelve documented ordering mistakes totaling roughly $18,600 in wasted budget. Most of those could have been avoided with better questions. So I wrote this FAQ. It's the list I wish someone handed me before I started ordering from Martin Sprocket & Gear. I don't work for them—I'm a customer—and I've ordered from their Fort Worth branch enough times to learn the hard lessons. Here's what I tell new engineers:

What does the Martin Sprocket logo actually tell me?

When you see the Martin Sprocket logo on a box, hub, or nameplate, it means the part came from Martin Sprocket & Gear. That sounds obvious, but I've learned to check. Unmarked sprockets and gears show up in surplus bins and online listings. Some are fine. Some are not. I won't install one without a logo because I can't trace it back to a catalog spec. The logo is essentially a traceability marker. It also helps when you need replacement parts—the embossed part number on the hub often links to a catalog page. If the logo is missing, I pass. Not ideal, but workable. To be fair, some older parts have logos that are worn off after years of service. That's fine if the part came from a known machine. But for new orders? I want the logo.

What should I know about the Martin Sprocket & Gear - Fort Worth Branch?

When I first started ordering from Martin Sprocket & Gear, I assumed the Fort Worth branch had every catalog item in stock. Wrong. The branch has a solid inventory, but not everything sits on their local shelves. Some products ship from another distribution center. The first time this happened, we needed a gear reducer in two days. The branch came through—eventually—but the lead time wasn't what I expected. Here's the thing: before you place a rush order, ask two questions. Is the item physically at Fort Worth? If not, what's the real transfer time? That one conversation has saved us more than once. The branch staff know their stuff, but they can't ship what isn't in front of them. Not every "in stock" means same-day pickup either. I'd rather know the truth before I promise a production date.

What uses a bevel gear?

Bevel gears are used wherever power needs to change direction, usually at a 90-degree angle. You'll find them in automotive differentials, right-angle gear reducers, conveyor corner drives, printing presses, marine drives, and even hand drills. The chuck on a drill is a classic example: the bevel gear transfers rotation from the motor axis to the chuck axis. If you need a right-angle power path, a bevel gear set is usually the solution. But "bevel gear" is not a finished part number. You need to match tooth style—straight, spiral, or hypoid—plus ratio, shaft angle, and mounting orientation. Straight bevel gears are simple and cheap but noisier. Spiral bevel gears run smoother. Hypoid gears allow offset shafts, like in a car differential. People order one bevel gear instead of a set. That's a mistake. Gears run in pairs. Order the pair, or at least verify the tooth match.

How do I pick a gear reducer without making my life miserable?

Start with the application, not the part number. A gear reducer is defined by ratio, input speed, output torque, service factor, and mounting position. AGMA—the American Gear Manufacturers Association—publishes service factor tables because real machines see shock loads, not just smooth theoretical loads. If you undersize the service factor, the reducer fails early. If you ignore mounting position, oil can't get to the right places, and the reducer overheats. I once ordered a reducer with the exact ratio I needed but the wrong input shaft diameter. The motor didn't fit. $1,900 sat on a pallet for a month. We didn't have a formal order verification process then; now we do. Write down the shaft details, coupling style, and duty cycle before you call. Don't assume the catalog page knows your motor. And if the application uses a motor with a C-face or IEC flange, confirm the reducer input style. Those details matter more than the ratio.

What do I actually need to specify for linear actuators?

People remember stroke and load. Then they forget duty cycle. A linear actuator rated for 25% duty will overheat if you run it continuously. I learned this on a lift gate that worked for ten minutes and then stopped. The specs that matter: stroke, dynamic load, speed, voltage, duty cycle, retracted length, mounting style, and IP rating. Oh, and draw the worst-case mounting position. The Martin catalog shows these specs—actually, the dimension drawings show them. Read the drawing. If you're replacing an existing actuator, measure the retracted length before you order. I've had a replacement that was an inch longer than the old one. One inch. Didn't fit. Measuring twice is now part of the checklist. Also check whether you need a limit switch, feedback signal, or emergency stop. Getting the basic actuator right is great, but missing the control option sends you back to the drawing board.

Can I use an old Martin part number from a drawing?

Sometimes. But part numbers get superseded. Revisions happen. A gear that was available ten years ago may have been redesigned, and the new version might not have the same shaft keyway or face width. I used to trust old drawings. Then a full batch came in with a slightly different flange pattern. It took me three years and a scrapped order to understand that verification is part of the job. Now, if the drawing is older than two years, I search 'martin-sprocket' to find the current catalog page or call the Fort Worth branch. We've caught 47 potential errors using this checklist in the past 18 months. Not one of those was a fun surprise. All of them would have been expensive. The extra ten minutes of checking beats a reorder cycle and downtime every time.

When should I NOT order a standard Martin component?

Honest answer: when the application is outside catalog limits. Standard gear reducers and linear actuators work for most industrial applications—maybe 80% of them. But if you need food-grade lubrication, continuous washdown, extremely high ambient temperature, or non-standard backlash for a servo application, don't force a standard part into a custom problem. Call Martin's engineering support. They'll tell you if the standard part works or if you need something else. That's not a weakness. It saves everyone from a failed installation. I get why people want one supplier to handle everything. That said, one supplier is great until you put the wrong part on a critical machine. Check the catalog limits first. Simple.

What's the correct way to measure a sprocket before ordering?

You can't order a replacement sprocket by saying "it looks like an 18-tooth." You need chain pitch, number of teeth, bore size, keyway width, and set screw location. If the sprocket has a bushing, identify the bushing size instead of measuring the bore. I once sent a photo of a sprocket to a supplier and asked for a match. The photo came back with three different possibilities. The real fix was simple: count the teeth, measure the pitch, and check the hub diameter. I keep a small caliper with inch and metric scales on my desk. Best $30 I ever spent. The Martin catalog lists sprockets by pitch and tooth count, so a quick identification saves a lot of back-and-forth. If in doubt, ask the Fort Worth branch before you order. They'd rather answer a simple question than process a return.