Product Categories / Mounted Bearings / Pillow Block Bearing / UCSAO318

UCSAO318

Name: UCSAO318 Pillow Block Bearing
Brand: LILY

$213.62 /Each

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Overview
Part Number	UCSAO318
Brand: LILY	Interchangeable With: AMI
Bearing Part Number	UC318
Housing Part Number	SAO318
Characteristics
System of Measurement	Metric
Bearing Type	Ball Bearing
Bearing Seal Type	Double Sealed
Inner Ring Type	Wide Inner Ring
Mounted Type	Pillow Block Bearing
Shaft Mount Type	Set Screw Locking
Product Series	UCSAO300
Lubrication Fitting Tap	1/8-27 NPT
Dimensions
Bore Dia	90 mm
Bore Dia Tolerance	-0.0005" to 0"
Bearing Width	96 mm
Hole Width	29 mm
Hole Length	45 mm
Overall Height	251 mm
Pillow Height	57 mm
Center Height	130.2 mm
Whole Length	409 mm
Hole Ctr-to-Ctr Min	320 mm
Hole Ctr-to-Ctr Max	359 mm
Width of Inner Ring	120 mm
Mounting Bolt Size	M27
Material
Bearings Material	AISI 52100 Steel
Housing Material	Cast Iron
Performance
Temperature Range	-30° to 110 °C
Properties
RoHS	Compliant
REACH	Compliant
Lubrication	Required
Weight	24.53 kg

UCSAO318 Pillow Block Bearing data sheet

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What does UCSAO318 mean?

UCSAO318 is an AMI metric cast iron pillow block unit with a wide inner ring insert and set screw locking, for a 90 mm shaft. The part number breaks down into 4 segments:

UC: Wide inner ring ball bearing insert, set screw locking, spherical outer ring. Insert part number is UC318

SAO: Housing style: cast iron pillow block. Housing part number is SAO318

3: 300 series (heavy duty)

18: Bore code: 18 × 5 = 90 mm

Note: For metric mounted bearings, the bore is usually the bore code × 5 mm. Codes 00, 01, 02 and 03 are the exceptions: 10, 12, 15 and 17 mm.

Frequently asked questions

What does UCSAO318 mean?

UCSAO318 is an AMI metric cast iron pillow block unit with a wide inner ring insert and set screw locking, for a 90 mm shaft. UC = wide inner ring ball bearing insert, set screw locking, spherical outer ring. Insert part number is UC318, SAO = housing style: cast iron pillow block. Housing part number is SAO318, 3 = 300 series (heavy duty), 18 = bore code: 18 × 5 = 90 mm.

What is the bore size of UCSAO318?

The bore of UCSAO318 is 90 mm.

The housing of pillow block bearing, crafted from iron, is engineered to withstand heavy-load and high-vibration conditions with the structural rigidity and dimensional stability needed to keep the overall mounted bearing assembly performing reliably over the long term.

Shaft retention is achieved through set screw locking in this pillow block bearing unit, which secures the shaft reliably against moderate loads and low-to-medium vibration — provided the shaft is of standard ground finish and the screws are correctly torqued — without damaging the shaft surface.

Two M27 bolts fasten the mounted bearing unit to the mounting surface, providing a secure and stable foundation that suits both new installations and direct replacement applications. M27 falls within the extra heavy-duty range, used where both the bearing load capacity and the structural demands of the mounting surface are exceptionally high.

Why choose Iron for the bearing housing?

Because this pillow block bearing is specifically designed for heavy-load and high-vibration conditions, cast iron delivers superior rigidity and dimensional stability where lighter or polymer housings are prone to deformation under load, making it a purpose-built choice for this application rather than a generic substitute.

Why does this bearing use Set Screw Locking to secure the shaft?

Set screw locking works by tightening one or two hardened screws directly against the shaft surface, which makes it well suited to applications where shaft positioning is fixed and loads are moderate. Its main advantage over other shaft locking methods is simplicity and low cost, which matters most when quick installation and minimal tooling are the priority.

How does the M27 affect installation and compatibility?

The bolt size directly determines whether the pillow block bearing can be mounted onto an existing frame or structure without modification. An M27 bolt corresponds to an extra heavy-duty hole pattern used where both the bearing load capacity and the structural demands of the mounting surface are exceptionally high, so when replacing an existing unit, confirming this dimension ensures a drop-in fit. Mismatched bolt sizes may require redrilling the mounting surface or sourcing an adapter plate, adding time and cost to the installation.