TR NA 210 insert bearing with eccentric locking collar. Dimensions: 50 mm bore diameter, 90 mm outside diameter, 43.7 mm overall width, and 68.2 mm locking collar OD.
TR NA Insert Bearing - Collar-Locked Ball Bearing for 25 mm to 50 mm Shafts
The TR NA insert bearing is built for equipment that is fabricated rather than precision-machined: conveyor frames, fan and blower shafts, farm implements, drive shafts on packaging and processing lines. Instead of relying on an interference fit, it grips the shaft with a collar on its extended inner ring, and instead of needing a bored cylindrical seat, its convex outer ring settles into a matching spherical housing. Between them, those two features remove most of the workshop preparation that a conventional bearing demands. The series covers five bore sizes - NA 205, NA 206, NA 207, NA 208 and NA 210 - spanning 25 mm to 50 mm shafts.
Each bearing in the series arrives greased and sealed on both faces, so it goes into service as it comes out of the box. The inner ring is longer than the outer ring, and that extension does two jobs at once - it carries the locking collar, and it spreads the clamping grip along more shaft length than a plain bore could manage. The outer ring is ground convex so it can swivel a small amount inside the housing seat, which is what allows two housings bolted to a slightly uneven frame to still run a shaft without edge-loading the raceways. The series is listed for material handling, agricultural machinery, fans and blowers, packaging lines, grain handling, textile and food processing plant, crushers and wastewater equipment.
Key Features of the TR NA Insert Bearing
Locking collar on an extended inner ring - clamps to plain commercial shafting without a press or interference fit
Convex spherical outer ring that self-aligns inside a matching housing seat
Seals fitted on both faces from new, with the bearing greased and ready to run
Five bore sizes in one series - 25, 30, 35, 40 and 50 mm - sharing the same fitting method
Outside diameters from 52 mm to 90 mm, matched to standard pillow block, flange, take-up and cartridge housings
Shaft surface left largely unmarked on removal, so the seat can be reused
Listed under HSN code 84831090
TR NA Insert Bearing Size Chart - All Five Variants
Quick answer: Match your shaft diameter to the bore column and the model is decided; then check the outside diameter against your housing before you order anything.
This is the fastest way through the series. Find your shaft size on the left, read across, and confirm the outside diameter will seat in the housing you already have:
Model
Bore, Outside Diameter and Width
Locking Collar OD
TR NA 205
25 mm bore, 52 mm OD, 31 mm width
37.4 mm
TR NA 206
30 mm bore, 62 mm OD, 53.7 mm width
44.1 mm
TR NA 207
35 mm bore, 72 mm OD, 38.9 mm width
51.1 mm
TR NA 208
40 mm bore, 80 mm OD, 43.2 mm width
56.5 mm
TR NA 210
50 mm bore, 90 mm OD, 43.7 mm width
68.2 mm
Read the width column rather than assuming it. Across this series the width does not simply climb with the bore - the NA 206 is listed at 53.7 mm, wider than both the NA 207 and the NA 208 above it. On a shaft that already carries a pulley, sprocket or coupling close to the bearing seat, that difference decides whether the bearing fits the space you have.
How Does the Locking Collar Hold the Shaft?
Quick answer: The collar slides onto the extended inner ring, is turned until it locks against it, and is then secured with its own grub screw - and it must be turned in the same direction the shaft rotates in service.
A conventional bearing is held on the shaft by friction from an interference fit, which is why it needs a ground seat and a press. The NA series replaces that with a mechanical clamp. The inner ring extends past the outer ring on one side, and the collar engages that extension. Turning the collar locks the two together and grips the shaft, so the bearing and shaft rotate as one unit.
The direction matters more than the effort. Turn the collar the same way the shaft runs and normal running torque works to keep it locked. Turn it the opposite way and running torque slowly works against the lock instead - the bearing will feel tight on the bench, hold for a while, and then start creeping loose no matter how hard the grub screw was tightened. If a collar-locked bearing keeps coming undone on a machine, this is the first thing to check, ahead of ordering a replacement.
The second thing to check is the shaft itself. Once a bearing has spun on a shaft, the seat is usually scored and slightly undersized, and a new collar then has less material to bite into. Measuring the seat with a vernier before refitting takes a minute and saves repeating the failure.
What to Check on Your Machine Before You Buy
Quick answer: Gather five things first - shaft diameter at the bearing seat, the condition of that seat, your housing bore and type, the direction the shaft turns, and the environment the bearing will live in.
The shaft seat, not the shaft Measure at the exact position where the bearing will sit, using a vernier. A stepped shaft or a section already worn by a previous bearing will give you a reading that sends you to the wrong model.
Condition of that seat Score marks, rust pitting or a visibly polished band mean the previous bearing moved on the shaft. That surface needs building up or sleeving - a collar cannot make up for missing material.
Housing bore and housing type If you are reusing the existing housing, its bore has to accept the bearing outside diameter, and its seat has to be spherical rather than straight. Note whether it is a pillow block, a two-bolt or four-bolt flange, a take-up or a cartridge.
Direction of rotation Note which way the shaft turns in service, and whether it ever reverses under load. Collar locking is set around one running direction, so this changes what suits your machine.
Working environment Dust, washdown, grain husk, chemical mist or high ambient temperature all affect how a sealed bearing behaves and how often it will need attention. Note it before you choose, not after.
Any markings on the old bearing Even a partly legible ring face is worth more than every measurement combined, because the designation settles bore, outside diameter, width and locking type in one reading.
Step-by-Step Guide to Selecting the Right TR NA Insert Bearing
Quick answer: Shaft diameter gives you the model, housing bore confirms it, collar clearance and rotation direction validate it - in that order, one step at a time.
Measure the shaft at the bearing seat. Take the reading with a vernier at the exact mounting position. Round nothing - 30 mm and 32 mm are different bearings, not the same bearing with a little play.
Read the model straight off the bore. Take your measurement to the size chart above and the whole series narrows to one part in a single step.
Confirm the outside diameter against the housing. The chart gives the outside diameter for that model - check your housing bore accepts it. If you are buying a new housing, order it to the same size code as the bearing.
Check width and collar clearance on the shaft. The collar stands proud on the inner ring side and needs room to be turned and locked. Look at what sits next to the bearing seat - a pulley, sprocket, coupling or frame member - and confirm both the bearing width and the collar diameter will clear it.
Confirm the rotation direction suits collar locking. A shaft that runs one way is straightforward. A shaft that reverses under load needs a conversation before ordering, not after fitting.
Match it to the duty and the environment. Finally, weigh the load and surroundings against the size you have arrived at. If the answer feels marginal, send the measurements over and we will work through it with you.
Locking Collar vs Set Screw - Which Insert Bearing Type Suits Your Shaft?
Quick answer: A locking collar grips around the shaft and leaves it unmarked, which suits vibration and shafts you intend to reuse; set screws release faster and work with rotation either way, but they indent the shaft and need re-checking.
Point of Difference
TR NA - Locking Collar
Set Screw Type
How the shaft is gripped
Collar locks against the extended inner ring and clamps around the shaft
Grub screws bite into the shaft surface at one or two points
Shaft after removal
Left largely unmarked, so the seat can be reused
Carries indentation marks where the screws bit in
Under sustained vibration
Running torque helps hold the lock, once set in the running direction
Screws can back off over time and need periodic checking
Direction of shaft rotation
Set around one running direction - ask us if your shaft reverses
Works with rotation either way
Fitting and removal
Collar turned by hand or with a drift, then locked with a grub screw
Hex key only - the quickest of the two to release
Typical use
Conveyors, fans, farm and processing equipment running one way
Light duty and equipment that is dismantled frequently
Mistakes to Avoid Before Buying an Insert Bearing
Quick answer: Nearly every wrong order comes from one of five assumptions - ordering on bore alone, assuming the old housing will fit, assuming width rises with bore, ignoring shaft wear, or ignoring rotation direction.
Ordering on bore diameter alone The bore tells you which shaft the bearing fits and nothing about whether it will enter your housing. Two bearings can take the same shaft and need completely different housing bores. Always pair the bore with the outside diameter before ordering.
Assuming the existing housing will take it Housings vary between makers in bolt spacing, base height and seat profile. A housing that looks identical to the one in the catalogue photo may not share a single mounting dimension with it. Measure yours.
Assuming width increases with bore In this series it does not. The NA 206 is listed at 53.7 mm wide - more than the NA 207 and the NA 208 that sit above it. Read the figure from the chart rather than estimating from the size code.
Fitting a new bearing to a worn shaft If the last bearing spun, the seat is undersized and scored. Clamping a new collar onto that surface simply schedules the same failure a few weeks out. Inspect and repair the seat first.
Ignoring which way the shaft turns Rotation direction is part of the specification for a collar-locked bearing, not an afterthought. Deciding it after the part has arrived is how a correct bearing ends up performing like a faulty one.
Throwing the old bearing away before ordering The markings on the ring face are the most reliable identification available, and they are gone the moment the part reaches the scrap bin. Clean the face and photograph it first.
When a TR NA Insert Bearing Is Not the Right Choice
Quick answer: It is the wrong bearing for high-speed precision assemblies, for significant thrust along the shaft, for continuous misalignment while running, and for shafts that reverse direction under load.
High speed or precision work Insert bearings are built for moderate speeds and general plant duty. Machine tool spindles, high-speed motors and anything needing a precision class call for a standard bearing in a machined housing instead.
Heavy load along the shaft This is a radial bearing. Where a shaft carries real thrust as well as radial load, an angular contact design is the correct family - not a larger insert bearing.
Misalignment that continues while running The spherical outer ring takes up mounting error once, at assembly, and then holds that position. A shaft that flexes under load or a frame that moves in service needs a stiffer shaft or a self-aligning bearing with two ball rows.
Shafts that reverse under load Collar locking is set around a single running direction. Reversing duty is worth discussing before you order rather than discovering after fitting.
Applications and Industries
Belt conveyors and material handling drive shafts
Agricultural machinery - harvesters, seeders and farm implements
Industrial fans, blowers and fan drive assemblies
Packaging line drive and roller shafts
Grain handling equipment and rotary drums
Textile processing and food processing plant
Crushers, mining machinery and heavy processing conveyors
Pump drives and wastewater treatment equipment
Frequently Asked Questions
Quick answer: It is the collar-locking type of mounted ball bearing - the kind you fit to a plain shaft with a drift and a hex key rather than a press.
Mechanically it is a single-row ball bearing altered for direct mounting. The outer ring is ground convex so it can settle into a matching housing seat, the inner ring runs longer than the outer to carry the collar that clamps it to the shaft, and both faces are sealed at the factory. The same component appears in other catalogues as a Y-bearing or a mounted bearing insert, so those terms describe the same part.
Quick answer: 25 mm takes the NA 205, 30 mm the NA 206, 35 mm the NA 207, 40 mm the NA 208 and 50 mm the NA 210.
Measure the shaft at the exact seat where the bearing will sit, then read the model off the bore. Before ordering, confirm the outside diameter against your housing and check that the collar has room to be turned. If your shaft measures between two sizes, it has probably worn - send the reading over rather than rounding it.
Quick answer: The last two digits are the bore code - multiply by five from size 04 upwards, so 06 means a 30 mm bore.
TR is the brand and NA identifies the locking-collar series. The bore code is an industry-wide convention, which is why an NA 206 and a 206 housing are designed to work together. It applies across the series: 205 is 25 mm, 207 is 35 mm, 208 is 40 mm and 210 is 50 mm.
Quick answer: A standard bearing needs a machined shaft seat, a press fit and a bored cylindrical housing. An insert bearing needs none of the three.
The insert version clamps to ordinary commercial shafting with its collar, drops into a spherical housing seat, takes up mounting misalignment, and comes sealed and greased. What it gives up is duty - standard bearings are available in higher precision grades for higher speeds and for machined assemblies such as gearboxes and motors.
Quick answer: It needs a housing with a spherical seat, sized to the same bore and outside diameter - pillow block, flange, take-up or cartridge.
The housing seat has to be concave to match the convex outer ring, which is what allows the bearing to align itself. Sizing is by bore and outside diameter together: 52 mm for the NA 205, 62 mm for the NA 206, 72 mm for the NA 207, 80 mm for the NA 208 and 90 mm for the NA 210. Because bolt spacing and base dimensions differ between manufacturers, send us your housing measurements and we will check the match against what you already have.
Quick answer: It corrects mounting misalignment at assembly. It does not correct a shaft that flexes while running or a shaft that is bent.
When two housings sit on a frame that is not perfectly true, the shaft no longer passes through both on a common axis. The spherical outer ring lets each bearing rotate slightly in its seat until it lines up, so the raceway loads evenly rather than on one edge. That adjustment is made once and then held - it is not a continuous compensation. For misalignment that persists in service, a self-aligning ball bearing with two ball rows is the correct design.
Quick answer: Tell us first. Collar locking is set around one running direction, so reversing duty changes what suits the machine.
On a shaft that turns one way, running torque works in favour of the lock. On a shaft that reverses under load, that advantage is lost for half the duty cycle. It is a question worth settling before the order rather than after fitting, so send the details of the drive and we will go through the options with you.
Quick answer: No - it arrives greased and sealed, ready to run. Where a relubrication point is fitted, top it up sparingly rather than filling it.
Add grease slowly with the shaft turning, and only enough to purge the old grease through. Overfilling a sealed bearing raises its running temperature and can push the seals out of position, which lets contamination straight in - so more grease is not a safer choice. Keeping the area around the seal clean matters just as much in dusty conveyor and agricultural work.
Send us the shaft diameter at the bearing seat, your housing bore, and which way the shaft turns. We will work through the fitment with you and point you to the right variant in the series - and if the old bearing still has readable markings on the ring face, a photograph of it usually settles the question on its own.
