Mounted bearing installation: pillow blocks, locking collars and set-screw torque
Install a mounted bearing as a complete shaft-support system: identify the insert and housing, check the shaft and mounting surface, align the supports, and apply the locking procedure for that exact bearing. Housing bolts, insert set screws and eccentric-collar screws are different fasteners. Their torque values are not interchangeable.
On this page15 sections ⌄
Identify the insert, housing and complete unit separately
A two-piece split plummer-block housing with a separate spherical roller bearing is not the same service job as a small UC insert unit. The set-screw examples on this page concern the named NTN insert families; they do not replace split-housing, adapter-sleeve or rolling-bearing fit instructions.
On smaller screens, scroll the table sideways to read all columns.
| Marking or feature | What it identifies | What still needs checking |
|---|---|---|
| UC205 insert example | A set-screw locking insert bearing | Housing type, mounting dimensions, shaft fit and complete-unit suffix |
| UCP / UCF / UCFL examples | Pillow-block / four-bolt flange / two-bolt flange unit families | Manufacturer drawing, exact shaft bore, bolt centres and permissible load |
| UCT example | An insert in an adjustable take-up housing | Frame guide dimensions, adjuster, travel and conveyor requirements |
| Spherical insert outer surface | A seat allowing initial alignment within the unit design | Not unlimited running misalignment or permission for a bent shaft |
| Grease fitting or lubrication suffix | A possible relubrication provision | Actual internal passage, insert compatibility and permitted grease |
Mounting surface, shaft and alignment checks
Use a rigid support that seats the housing without rocking or twisting. Check the actual shaft diameter, surface condition and the tolerance required by the locking system. A loose shaft, damaged journal or wrong insert bore is not corrected by extra tightening.
NTN catalogue 2400/E, printed page 51, specifies a mounting-surface flatness target of 0.05 mm maximum for its installation guidance. This is a source-specific reference, not a universal tolerance for all brands, resin housings or machine structures. Use the applicable current drawing and equipment instructions.
The same NTN guidance limits the mounting-surface-to-shaft angle to ±2°, with ±1° for the stated narrow-outer-ring and covered-unit cases. These are installation/alignment limits in that catalogue, not a continuous dynamic-misalignment rating or a remedy for shaft bending.
Locate both supports so that fastening does not pull the shaft into a forced position. Where the machine requires axial expansion accommodation, retain its intended locating and non-locating arrangement; do not improvise two rigid axial locations.
Set screws vs eccentric collar vs adapter sleeve
A collar screw is not necessarily the same fastener as a screw acting directly on the shaft from the insert ring. For example, NTN table 11.4 gives a 7.8 N·m maximum for the UEL204–205 eccentric-collar screw, while table 11.3 gives 3.9 N·m for UC201–205 insert set screws. The similar-looking assembly does not justify sharing a torque value.
On smaller screens, scroll the table sideways to read all columns.
| Method | How it locks | Selection / installation boundary |
|---|---|---|
| Insert set screws | Screws in the inner ring secure it to the shaft | Tighten the specified screws uniformly with the correct torque; do not infer the value from thread size alone |
| Eccentric collar | The collar engages an eccentric inner-ring extension; its own screw retains the collar | NTN instructs locking in the direction of shaft rotation; its eccentric system is not recommended for reversing rotation |
| Adapter sleeve | A tapered sleeve and nut establish grip between bearing and shaft | Use the designated sleeve, nut and washer procedure; excessive tightening reduces internal clearance |
| Other concentric clamp systems | A manufacturer-specific collar or sleeve clamps around the shaft | Do not substitute the eccentric-collar or UC set-screw sequence without the actual instructions |
NTN UC insert set-screw torque examples
NTN 2400/E table 11.3, printed page 55. These are the catalogue maximum tightening torques for the listed bearing groups and standard metric screw designations. They are not housing-bolt torques or a generic fastener chart.
Match the full bearing and screw specification before using a value. The same MSS6 screw designation appears with UC206 at 4.9 N·m and UC207 at 5.8 N·m; MSS8 likewise has different values for UC208–210 and UC211. Use the bearing-specific row, not a single value for every screw size.
This excerpt does not specify the corresponding inch-thread or stainless screw variants. Do not replace an inch screw with a visually similar metric screw. Use an appropriate calibrated tool and follow the exact unit’s sequence and inspection requirements.
On smaller screens, scroll the table sideways to read all columns.
| NTN insert designation | Metric screw designation | Maximum N·m |
|---|---|---|
| UC201–205 | MSS5 | 3.9 |
| UC206 | MSS6 | 4.9 |
| UC207 | MSS6 | 5.8 |
| UC208–210 | MSS8 | 7.8 |
| UC211 | MSS8 | 9.8 |
| UC212 | MSS10 | 16.6 |
| UC213–215 | MSS10 | 19.6 |
| UC216 | MSS10 | 22.5 |
| UC217–218 | MSS12 | 29.4 |
Do not confuse housing fastening with shaft locking
A bolt reference table does not establish the strength of the base material, washers, threads or a particular housing. Resin units have separate model-specific values in the NTN table. Over-tightening can distort the housing or damage its seat even when the shaft-locking operation was correct.
On smaller screens, scroll the table sideways to read all columns.
| Fastener | Named source example | Why the distinction matters |
|---|---|---|
| Housing mounting bolt | NTN table 11.1: M10 reference range 14–24 N·m, excluding resin housings | Secures the housing to its support; not a value for the bearing’s inner-ring screw |
| Housing mounting bolt | NTN table 11.1: M12 reference range 25–41 N·m, excluding resin housings | Actual housing and bolt specification still govern; do not apply this range indiscriminately |
| UC205 insert set screw | NTN table 11.3: 3.9 N·m maximum | Locks the insert to the shaft, not the base to the machine |
| UEL204–205 eccentric-collar screw | NTN table 11.4: 7.8 N·m maximum | Retains the eccentric collar after its specified locking operation |
Grease fittings, sealed units and relubrication
Confirm whether the complete unit is intended for relubrication. A grease fitting added to an arbitrary housing does not establish a passage into a replacement insert. Retain the correct housing passage, bearing groove/hole arrangement and compatible insert.
The NTN UCT2 reference uses D1 for the listed relubricatable version and describes the corresponding catalogue version without D1 as maintenance-free. This suffix convention belongs to that product reference; it is not a universal decoding rule for every bearing manufacturer.
Select grease, quantity and interval from the actual speed, load, temperature, contamination and unit instructions. Do not assign every pillow block the same calendar interval or mix greases because their colours match. Excess grease and blocked passages can be as problematic as insufficient supply.
Removing the unit from the shaft vs removing the insert from its housing
Keep removal loads and tools appropriate to the actual assembly. Adapter-sleeve units require their own release procedure and adequate thread engagement; the set-screw/tilting instructions above are not a universal adapter or split-plummer-block procedure.
On smaller screens, scroll the table sideways to read all columns.
| Stage | Required distinction | Stop or inspect |
|---|---|---|
| Remove a set-screw unit from its shaft | Back the screw tips fully clear of the bore before sliding the unit off | A protruding tip can score the shaft; do not force it through a raised burr |
| Replace an NTN insert after the unit is off the shaft | The catalogue then calls for the screws to be turned inward so their outer ends clear the housing during tilting | This is a different operation from shaft removal; never tighten onto a shaft as a removal step |
| Extract the replaceable insert from its seat | For the described NTN housing, tilt the insert 90° and align it with the loading notch | Do not generalize this to non-separable units or force a ring through an incompatible housing |
| Reuse the housing | Inspect the seat, mounting faces, cracking, wear and lubrication passage; install the specified compatible insert | A worn or damaged housing is not made serviceable merely by fitting a new bearing |
Installation questions
How tight should pillow-block bearing set screws be?
Use the manufacturer’s row for the exact insert, locking method and screw variant. The named NTN examples range by bearing designation; housing bolt size or shaft bore alone is not enough to select a torque.
Can an eccentric locking collar run in both directions?
The cited NTN guidance does not recommend its eccentric-collar system for reversing rotation. Identify a suitable documented locking arrangement for the machine rather than assuming the collar will remain secure.
Can I replace only the bearing inside a pillow block?
Some units have a replaceable insert, including the NTN arrangement described here. Confirm the housing seat, compatible insert, lubrication passages and condition first. This does not establish compatibility from bore diameter alone.
Does self-aligning mean alignment does not matter?
No. The seat accommodates limited initial alignment within the unit design. Support alignment, shaft condition, permitted movement and the actual running limits still matter.
What the evidence can — and cannot — tell you
| Observation or context | Interpretation to consider | Verification needed |
|---|---|---|
| Exact assembly | Insert, housing, locking method and full suffix | A UC insert number alone does not identify the complete pillow block. |
| Safe access | Isolated drive, supported shaft and released stored load | A stopped motor is not proof that a tensioned belt or shaft cannot move. |
| Sound mounting | Measured shaft, clean seat and aligned supports | Do not pull a distorted base flat by over-tightening the bolts. |
| Correct locking | Specified tools, sequence and series-specific torque | An M6 thread size is not a universal bearing set-screw torque. |
Plan the work safely
Identify and record
Isolate the equipment against unexpected movement and support the shaft and attached components. Record the complete unit and insert identifiers, shaft diameter, housing position, locking method and lubrication arrangement before dismantling.
Check the context
Inspect and measure the shaft and mounting surfaces. Remove burrs without altering the specified fit. Position the identified unit squarely on the shaft with screw tips clear of the bore; do not strike the flinger or force an unsuitable fit.
Verify before acting
Align and fasten the housing according to the equipment and unit instructions. Establish the specified locating/floating arrangement before locking the insert. Use the correct set-screw, eccentric-collar or adapter procedure and its own tightening specification.
Keep the decision traceable
Verify the locking parts, shaft freedom, guards and lubrication provision before a controlled test. Monitor noise, vibration and temperature, and perform only the rechecks required by the relevant instructions. Stop if binding, loosening or abnormal heat appears.
Capture the information a model search cannot guess
Keep this checklist with your inspection or comparison. Checking a box only records that you have collected the item; it does not certify the bearing.
0 of 4 information groups recorded.
Technical basis & editorial scope
Original BearingScope workflow, written for catalogue research and comparison. Manufacturer material is used to check principles, not copied as a product endorsement or substituted for model-specific instructions. Reviewed 1 October 2026.
- NTN Bearing Units catalogue 2400/E, technical data, printed pages 50–60 — Guide/frame dimensions, housing mounting, insert locking and replacement; series-specific reference, not a universal torque standard.
- NTN Bearing Units catalogue 2400/E, UCT2, printed pages 212–216 — Metric and inch take-up unit designations and nominal dimensions; D1 lubrication scope retained.
Source addresses and collection status are retained in the internal audit. No unpublished dimensions, torque settings, service intervals or interchange approvals are inferred.