Koyo Bearings FAQ: Thrust vs. Deep Groove, Catalog PDF, 35 Roller Chain, and What a VFD Is

I work on the rush-order side of an industrial bearing supply company. Since 2019, I've helped handle more than 200 Koyo bearing orders where the customer needed it yesterday — some same-day, some with freight costs that made accounting wince. When a machine is down, the difference between a useful answer and a sales script is usually specificity.

Here are the questions that keep coming up about Koyo bearings, answered the way I'd explain them on the phone.

• Koyo thrust bearings vs. deep groove ball bearings
• Koyo bearings catalog PDF
• What's a VFD?
• Does Koyo make 35 roller chain?
• Shielded or sealed Koyo bearings
• Emergency replacement information
• Why the quote doesn't match the catalog PDF

1. Can a Koyo thrust bearing replace a deep groove ball bearing?

No, not for a radial-load job. Start with load direction: thrust means force along the shaft; deep groove means force perpendicular to the shaft plus a moderate amount of axial load. Koyo thrust bearings are made for axial loads, such as a vertical shaft or pump impeller. The deep groove ball bearing series, usually 62xx or 63xx, is the workhorse in electric motors, gearboxes, and conveyor pulleys. It can take radial load and some thrust, but it is not a substitute for a Koyo thrust bearing when the axial load is heavy.

If you put a thrust bearing into a housing designed for a deep groove bearing, the shaft won't be stabilized radially. The result is usually heat and premature failure. If the application truly has both radial and axial loads, look for an angular contact ball bearing or design the support with a radial bearing plus a thrust bearing. In short: identify the load direction before you identify the bearing series.

2. Where can I find the Koyo bearings catalog PDF?

The safest place is Koyo/JTEKT's official site or an authorized distributor portal, not a random file-sharing page. As of January 2025, the Koyo bearings catalog PDF is generally published by product family. Check the file date and revision before you trust a part number from it. If the page has no date, no revision and no suffix legend, treat it as an old snapshot.

The reason this matters on a rush order: a catalog PDF is how you verify dimensions, load ratings, suffixes, and clearance classes. Official Koyo technical data uses standards such as ISO 76 and ISO 281 for rating calculations. If a seller shows the same bore, OD and width but can't show the rating basis, they're guessing. That's a gamble, not an equivalent.

3. What's a VFD, and why does it matter for bearing life?

VFD stands for variable frequency drive. It controls AC motor speed by changing the voltage and frequency delivered to the motor. A VFD is not a Koyo product and it is not a bearing type, but it can change the way motor bearings fail.

Modern VFD output pulses can create voltage on the motor shaft. If that voltage discharges through a bearing, it leaves fluting marks on the raceway. The bearing gets noisy and then fails well before its mechanical service life. I've seen a motor lose two standard bearings before someone checked the drive and grounding. The bearings weren't defective; the electrical path was the problem. If you're replacing a bearing on a VFD-driven motor, talk to the motor supplier about Koyo's insulated bearing options. And check the grounding path first. Otherwise, you'll be replacing the same bearing in a few months.

4. Does Koyo Bearings make a 35 roller chain?

No. 35 roller chain is an ANSI roller chain size with a 3/8-inch pitch, and it is not part of Koyo's bearing catalog. I understand the confusion: industrial e-commerce sites group chain, sprockets, shafts and bearings under the same drivetrain category, so you can get a search result that makes them look like one product family.

If you need parts for a conveyor that uses a 35 roller chain, the Koyo component is the bearing supporting the shaft. The chain itself is selected on tensile strength and speed, while the bearing is selected on shaft diameter, housing type, load and speed. On a small conveyor, that is often a deep groove ball bearing or a pillow block. Also check sprocket alignment before ordering another set of bearings. A new 35 roller chain pulling sideways can ruin good bearings in a month, and alignment won't show up in any bearing catalog.

5. Should I choose a shielded or sealed Koyo deep groove ball bearing?

It depends on the environment and speed. A metal shield keeps out larger particles and helps retain grease. A rubber seal keeps out finer dust and moisture, but it can create more friction and heat. That's why sealed bearings are not automatically better than shielded ones.

Match the construction to the application. On a clean motor running at high speed, a shielded bearing is often the original specification. On a dusty conveyor or outdoor gearbox, a sealed bearing is usually worth the extra drag. The wrong choice shows up as either contamination inside the bearing or an overheating bearing. The same Koyo deep groove ball bearing can be ordered open, shielded or sealed, and the difference is in the suffix code. This is where online lookups fail. The catalog PDF tells you what the suffix means, and that's not a detail to skip.

6. What do I need for an emergency Koyo bearing order?

When I'm triaging a rush order, I ask for six things: the full part number, bore, outside diameter, width, seal/shield construction, and the suffix. If you don't have the original box, photograph the bearing face before cleaning it. The marking might be worn on one side and readable on the other.

It took me four years and a few expensive mistakes to understand that the last characters of a Koyo part number matter as much as the base number. A deep groove ball bearing with C3 clearance is not an upgraded version of a standard clearance bearing; it has more internal clearance for specific fits and operating temperatures. Ordering by footprint causes failures that look like quality problems but are really specification problems. If the old bearing is gone, measure the shaft and housing before calling anyone. Then verify the part number on the Koyo bearings catalog PDF. Spending twenty minutes checking is cheaper than paying for overnight freight twice.

7. Why is the price in the Koyo catalog PDF different from the quote?

Because a catalog PDF is a technical document, not a price list. If it lists prices at all, they are usually list prices. Distributor quotes depend on volume, location, exchange rates, lead time and current market supply. That part is normal.

What is not normal is finding out about charges after the order is placed. I've learned to ask what is NOT included before asking for a lower price. Is freight included? Is the bearing coming from a local warehouse or an overseas plant? What happens if the order needs to be expedited? A supplier who lists all of that upfront—even if the total looks higher—usually costs less in the end. Surprise freight and handling fees cause more friction than bearing prices. The catalog PDF is the technical truth; the quote is the commercial truth. Ask for both from the same supplier, and verify every suffix before you send the PO.