Boston Gear FAQ: 700 Series Catalog PDF, FANUC Servo Motor Repair, and Answers I Learned the Hard Way

I've been ordering transmission components for industrial clients since 2017. Eight years in, I've made roughly 30 significant mistakes that added up to about $25,000 in wasted budget. Not exactly proud of that. But I documented all of them, and now that documentation is our team's ordering checklist. This FAQ covers the questions I get asked most often, plus a few you should be asking but probably aren't.

What is Boston Gear?

Short answer: a power transmission brand with serious history. Boston Gear's roots go back to 1877, and today the brand sits under Regal Rexnord's industrial portfolio. The product line is broad—speed reducers, gearboxes, spur and worm gears, servo and stepper motors, ball bearings, linear actuators.

For most people reading this, though, "Boston Gear" means the 700 series worm gear reducers and the catalog that documents them. If you work around conveyor lines, packaging machinery, or material handling equipment, you've almost certainly touched one, even if you didn't realize it at the time.

Where can I find the Boston Gear 700 series catalog PDF?

The official source is bostongear.com. As of January 2025, the 700 series catalog is available under their Literature section. Major distributors like Motion Industries also host copies on their portals. Whether you search "boston gear" or "boston-gear," that's where you'll land.

My tip: download the searchable version and give Ctrl+F a workout. I once spent two hours flipping through printed pages to identify a worm gear. The PDF would have found it in 90 seconds. Don't be me.

The catalog includes the engineering tables you actually need—service factors, thermal ratings, shaft configurations. The part number on your order has to match all of those, not just the ratio. I once ordered a 700 series reducer based on the old unit's nameplate without checking input shaft orientation. Great ratio. Wrong product. Left-hand input versus right-hand input is a real thing, and yes, I found out the expensive way ($3,700, to be specific). The catalog tells you which configuration is which. Read it before you order, not after.

What's a ball bearing?

Simple version: a bearing lets two moving parts work against each other with minimal friction. A ball bearing does this with small steel balls sandwiched between two rings, turning sliding friction into rolling friction.

If that sounds basic, good. The part that trips people up: not all ball bearings are equal. Load rating, speed rating, and seal type all matter. I once bought stainless steel ball bearings because they sounded premium. Stainless is about corrosion resistance, not strength—and the load rating was too low for the conveyor application. $1,800 of shiny bearings failed within six months. The correct bearing was a standard alloy, rated for the real load, and cheaper. Read the spec sheet, not the marketing name.

Also, when you're identifying a replacement bearing, the numbers on the bearing itself matter. Series, bore size, seal code, clearance. A 6203-2RS is not the same as a 6203-ZZ, and they're not necessarily interchangeable for your application. If you can't read the worn numbers, measure the bore, OD, and width before you order.

FANUC servo motor: repair or replace?

This question comes up constantly, and it's where I'll draw my own boundary: FANUC servo motor repair is a specialty. I'm not the repair shop. But after years of watching orders go through, here's what I've seen make sense:

• Encoder or brake failure: repair is often worth it—these components can be replaced at reasonable cost.
• Bearing noise: might be a straightforward bearing swap, depending on the extent of the wear.
• Winding failure on a motor over ten years old: start comparing replacement costs seriously.

The mistake I keep seeing—and made myself in 2022—is sending the motor in without a proper diagnosis. We sent a FANUC unit with "doesn't run right." It came back "fixed." Eight months later it failed under load. $1,200 repair down the drain. A new motor would have been about $2,100 with a warranty. Hindsight. Simple.

My rule now: pay for the diagnostic first. If the repair estimate is more than half the replacement cost and the motor is old, replace it. And find a shop that specializes in FANUC specifically—not a generalist motor shop.

"A repair shop that says 'this isn't our specialty—here's who does it better' earns more trust than one that claims to fix anything."

That's not just me being philosophical. It's the difference between a vendor who wants your repeat business and one who wants your money once.

Speed reducer, gearbox, or gear reducer: what am I actually ordering?

Gearbox is the generic term. A speed reducer—or gear reducer—is a gearbox built to reduce speed and increase torque. When someone says "gear reducer" without more context, they usually mean a worm gear speed reducer, which for Boston Gear brings you straight back to the 700 series. (And no, "fever reducer" won't help your conveyor line. Different aisle entirely.)

Here's what most buyers focus on: the ratio. Here's what they should focus on first: duty cycle and service factor. Ratio is just gear teeth math. Service factor is the safety margin between the catalog rating and your actual load—the multiplier that tells you whether a reducer rated for 5 HP can handle the 7 HP motor plus shock loads without overheating or wearing out in eighteen months.

In 2023, I installed a 700 series unit on a conveyor running 16 hours a day. The ratio was right. The service factor was not. The unit ran hot. Very hot. The thermal rating was sitting in the same catalog I just told you to read. That was a $1,900 lesson in reading the whole spec sheet, not just the first page.

Spur gears or worm gears?

Quick version: spur gears suit parallel shafts, deliver high efficiency, and make more noise. Worm gears suit right-angle drives, give you higher reduction ratios, run quieter, and trade away some efficiency in exchange for generating more heat. Both have their place.

The conventional wisdom is to pick the most efficient gear type and make everything else work around it. My experience with hundreds of orders says the opposite: start with the physical layout and duty cycle, then choose the gear. I watched a colleague force a spur gear setup because "spur gears are more efficient," while the application clearly needed a right-angle drive. The custom brackets, extra shaft bearings, and engineering hours cost more than any efficiency gain. The machine worked. It was also a monument to ignoring the obvious. Product choice starts with the application, not with a preference for one gear type.

Is the Boston Gear 700 series catalog still relevant today?

Nobody asks this question, but they should. Yes—because the installed base is enormous. Plants are still running 700 series reducers that went in twenty or thirty years ago. When a nameplate is worn off and maintenance needs a replacement fast, the catalog PDF is how you identify what's bolted to the frame.

In September 2024, a customer's reducer died and the identification plate was unreadable. We pulled up the 700 series PDF, compared frame dimensions and shaft layouts against the old unit, and found the match. Part number confirmed. Replacement unit on site in four days. That's the power of a good catalog and a product line that's stayed consistent for decades.

One last note for anyone tempted to buy a "good enough" equivalent and make it fit: I've spent an uncomfortable chunk of my $25,000 doing exactly that. For intermittent, low-load, forgiving applications, you might get away with it. For continuous duty with safety implications, get the part that was designed for the job. Future you—and your maintenance budget—will be grateful.