UCT321 Bearing Dimensions
UCT321 take up bearing unit: 105 mm bore, T321 housing + UC321 insert. Frame dimensions H 290 / L 345 mm, designation and size-equivalent codes.
UCT321 specifications
| Shaft diameter d | 105 mm |
|---|---|
| Dimension H | 290 mm |
| Dimension L | 345 mm |
| Dimension L1 | 210 mm |
| Dimension N2 | 115 mm |
| Insert width B | 112 mm |
| Seal / shield options | Sealed insert bearing (UC type) with cast iron housing |
| Material | Insert: GCr15 chrome bearing steel (rings and rolling elements); housing: cast iron |
| Precision | P0 (standard) |
| Radial clearance | C0 (standard); C3 on request |
| Load ratings | Load ratings for this model are being checked against FULI's catalog. Ask for them with the quote. |
Dimensions cross-checked against published catalogues; please confirm with your quote. Letters follow the dimension drawing in FULI's catalog; ask us for the drawing.
How to read the UCT321 designation
| Segment | Meaning |
|---|---|
| UC | Insert bearing with set-screw locking and spherical outside diameter |
| T | Take-up housing (slides in a frame to tension a belt or chain) |
| 3 | 300 series (medium duty) |
| 21 | Bore code 21 → 105 mm bore. ISO bore code (00–03 = 10/12/15/17 mm; 04 and above = code × 5 mm). |
UCT321 interchange
UCT321 is a housed unit: a UC321 insert bearing in a T321 housing. The insert bearing dimensions follow ISO and interchange between manufacturers. Housing dimensions such as bolt hole spacing can differ between the JIS and ISO versions of the same designation, so please confirm the mounting dimensions with us before ordering.
Brand names are trademarks of their respective owners. FULI is not affiliated with, authorized by or endorsed by these companies. Part numbers are shown for interchange reference only. FULI dimensions, load ratings and speeds come from the FULI catalog.
UCT321 compared with nearby sizes and housings
UCT321 is a take-up unit that holds the UC321 insert on a 105 mm shaft: dimension H 290 mm, dimension L 345 mm, dimension L1 210 mm and dimension N2 115 mm.
The same 321 size is also made as UCP321 (pillow block unit, d 105 · H 140 · J 380 mm) and UCFL321 (oval flange unit, d 105 · L 440 · J 360 mm). All of them take the same UC321 insert, so a worn insert can be changed without changing the housing type.
UCT326 is the next larger size in the same series on this site: shaft d 130 mm (25 mm more), inner ring width B 135 mm (23 mm more), dimension H 385 mm (95 mm more) and dimension L 465 mm (120 mm more).
| Model | Type | Main dimensions | Weight (kg) |
|---|---|---|---|
| UCT321 | take-up unit (this page) | d 105 · H 290 · L 345 mm | — |
| UCT326 | take-up unit | d 130 · H 385 · L 465 mm | — |
| UC321 | insert bearing | 105 × 225 × 112 mm (d × D × B) | — |
| UCP321 | pillow block unit | d 105 · H 140 · J 380 mm | — |
| UCFL321 | oval flange unit | d 105 · L 440 · J 360 mm | — |
Dimensions in mm from the model pages; weight from FULI's catalog, — = not listed on this site.
UCT321 load ratings
FULI's catalog has no load rating line for UCT321 itself, so none is given here. The ratings of the UC321 insert are on its own page. Ask us and we send the figures with the quotation.
UCT321 dimensions in inches
The nearest common inch shaft size to the 105 mm bore of UCT321 is 4-1/8 in (104.78 mm), 0.22 mm smaller than the bore, so UCT321 would be loose on it. An inch shaft needs an inch bore insert. Inch bore versions are made for some sizes; ask us with the shaft size.
| Dimension | Millimetres | Inches |
|---|---|---|
| Shaft diameter d | 105 mm | 4.1339 in |
| Dimension H | 290 mm | 11.4173 in |
| Dimension L | 345 mm | 13.5827 in |
| Dimension L1 | 210 mm | 8.2677 in |
| Dimension N2 | 115 mm | 4.5276 in |
| Insert width B | 112 mm | 4.4094 in |
Converted at 1 in = 25.4 mm and rounded to four decimals. The bearing itself is made to the millimetre sizes.
Mounting UCT321 (general guidance)
General guidance, not a FULI specification: insert bearings slide onto the shaft rather than being pressed on, and are held by their locking device. A shaft ground or drawn to h7 is common; a closer shaft such as js7 or j7 suits higher speed.
The UC321 insert in UCT321 is locked by set screws in the extended inner ring. Housed-unit problems usually start at the set screws: if the inner ring is not held, it turns on the shaft and wears it. Tighten each screw to the torque in the mounting instructions, and check them again after the first hours of running.
The housing of UCT321 slides in the guides of the frame. Set the belt or chain tension with the adjusting screw first, then lock the insert to the shaft.
Grease for UCT321
The insert in UCT321 is sealed on both sides and greased at the factory. If the housing has a grease fitting, add grease slowly through it while the shaft turns until a little fresh grease shows at the seals; general practice is to relubricate more often in wet or dusty places.
Greases for a stated temperature range can be specified on the order; for North America a range of −40 to 120 °C is often asked for.
How FULI supplies UCT321
FULI supplies UCT321 as a complete unit, or the UC321 insert on its own for replacement. Before packing, the factory checks the mounting torque, the fit of the insert in the housing, the radial clearance and that the base-to-centre height is consistent across the batch.
Rings are marked with a brand you are authorised to use, with the FULI brand, or left neutral, as your order states. The box is printed with the model, precision class and brand.
Inquiries that leave out the prefix or suffix letters are the usual cause of a wrong quote, so write the full designation, for example UCT321.
Tools and guides for UCT321
Typical applications
- Belt conveyor take-up (tail) pulleys
- Screw conveyors and bucket elevators
- Chain and belt tensioning on agricultural machinery
FAQ
What shaft size does UCT321 fit?
A 105 mm shaft (4.1339 in).
What is the difference between UCT321 and UCT326?
UCT326 is the next size up, for a 130 mm shaft, with inner ring width B 135 mm (23 mm more), dimension H 385 mm (95 mm more) and dimension L 465 mm (120 mm more). Choose UCT326 when the shaft is larger or the load is higher; the housings are not interchangeable.
Which insert fits UCT321?
The UC321 insert (105 × 225 × 112 mm). It is sold on its own for replacement.
UCT321 or UCP321: which should I use?
Both hold the same UC321 insert on a 105 mm shaft. UCT321 is a take-up unit (d 105 · H 290 · L 345 mm); UCP321 is a pillow block unit (d 105 · H 140 · J 380 mm). Choose by how the bearing is fixed to the machine: a pillow block bolts to a surface parallel to the shaft, a flange to a face across it.
Does UCT321 come as a complete unit or insert only?
UCT321 is normally supplied as a complete unit (insert bearing already fitted in the housing). The insert can also be quoted separately if you are replacing only the bearing.
Where are the load ratings for UCT321?
Load ratings for UCT321 are being checked against FULI's catalog and are not shown on this page yet. Model pages with a "Load ratings & speed" table carry values from FULI's catalog.