Koyo7017-5DB5-FG-P4Precision Angular Contact Ball Bearing Matched Pair – 85 mm ID, 130 mm OD, 22 mm Width Each, Open, 30° Contact Angle, Back-to-Back DB, Polyamide Cage

Product Description

What this part is

Koyo 7017-5DB5-FG-P4 is a precision angular contact ball bearing supplied as a factory-matched back-to-back duplex pair. Each bearing measures 85 mm bore, 130 mm outside diameter and 22 mm width, giving 44 mm across the assembled pair.

Decoding the designation

7017 places the bearing in the ISO 7000 light series on an 85 mm bore. In the Koyo scheme a 7000-series number carrying no angle letter is a 30° contact angle, where a C suffix would mean 15° and a B suffix 40°. DB is the back-to-back arrangement. FG is the polyamide resin cage. P4 is the tolerance class, equivalent to ABEC 7.

What these specs mean in practice

A 30° contact angle sits between the 15° high-speed types and the 40° thrust types, so it carries a substantially larger axial load than a 15° bearing while still running at precision speeds. Mounted back to back, the two outer rings meet at their wide faces and the pressure cones diverge, which gives the pair a wide effective bearing span and good resistance to overturning moments.

Cage material

The polyamide resin cage is light, quiet and tolerant of oil, and it reduces cage mass and friction against a machined brass alternative. Koyo lists the same envelope with brass FW and FY cages and a phenolic FT cage where higher temperature or heat resistance governs.

Quantity and configuration

Two pieces, one matched back-to-back pair. The rings are ground as a set so the preload establishes itself when both are clamped against square shoulders, with no shims or spacers involved. Both bearings carry axial load, one in each direction, and the pair locates the shaft in both directions.

Fitting notes

Mount the pair with the two outer ring wide faces together and clamp both inner rings and both outer rings fully home against square, ground shoulders. The set is matched, so the two bearings stay together as a unit through handling and installation. Cleanliness at assembly governs the running accuracy that the P4 grinding pays for.

Interchange guidance

Same-envelope 30° equivalents are NSK 7017A duplex and NTN 7017 duplex sets in a DB arrangement at an equal preload class. A 7017 carrying a 15° code — Koyo 7017C, SKF 7017 CD, FAG B7017-C — or a 25° code such as SKF 7017 ACD is a related size on the same 85 x 130 x 22 mm envelope rather than an interchange, because the contact angle sets the thrust and speed capability.