Timken5305KGDouble Row Angular Contact Ball Bearing, 25 x 62 x 25.4 mm, 20° Contact Angle, 37.7 kN Dynamic

Product Description

What this part is

A Timken Fafnir double row angular contact ball bearing in the 5300 medium series: 25 mm bore, 62 mm outside diameter, 25.4 mm wide. Two rows of balls run on angled raceways inside a single pair of rings. That construction gives it the one property a deep groove ball bearing cannot match at the same envelope — substantial thrust capacity in both directions from one bearing, with no need to set preload against a second bearing at assembly.

It is the answer to a specific design problem: a shaft that has to be located axially in both directions but has no room for two opposed single-row bearings and no provision for a shim stack or setting nut. Pumps, blower and fan shafts, worm gear inputs, agricultural gearboxes and light machine spindles are where these turn up.

The 20° contact angle — and why the brand on the ring matters here:
Timken publishes the contact angle for the 5305KG as 20°. This is the single most important number on the page and it is brand-specific, not a property of the 5305 designation. MRC’s 5305MG and 5305CG at the same 25 mm bore and 62 mm outside diameter are 30° bearings. Same nominal part number, same envelope, half again the contact angle.

What changes with the angle is the trade between thrust capacity and speed. A larger contact angle steers more of the load into the axial direction, raising thrust capacity and axial stiffness but increasing ball spin and heat generation, which lowers the practical speed limit. A 20° bearing is the more radial, faster-running, lower-heat option; a 30° bearing takes more thrust and is stiffer axially. Neither is better — they are different bearings.

The consequence for a buyer is direct: if your machine’s drawing specifies a 30° double-row angular contact bearing and you fit this 20° Timken unit because the number matched, you have reduced the axial capacity of the shaft. Check the angle, not just the digits. Where a rebuild is failing on thrust and the previous bearing was replaced “like for like” across brands, this is a very common root cause.

Published ratings and mounting data

All figures below are from Timken’s own catalogue entry for 5305KG.

Bore (d): 25 mmOutside diameter (D): 62 mm / 2.4409 inWidth (C): 25.4 mm / 1.000 inContact angle: 20°Dynamic radial load rating C1 (1 × 106 rev): 37,700 N / 8,500 lbfStatic radial load rating C0: 21,100 N / 4,750 lbfBall material: steelCage type: snap-inNumber of rows: 2Maximum shaft fillet radius: 1 mm / 0.039 inShaft backing shoulder diameter: 31.120 mm / 1.225 inHousing backing shoulder diameter: 54.100 mm / 2.130 inOuter ring “to clear” radius (r): 1 mm / 0.039 in

Why the backing shoulder diameters are on this page:
Because nobody publishes them and they decide whether your rebuild works. The shaft backing shoulder must be at least 31.120 mm in diameter to support the inner ring across its full face, and the housing backing shoulder no more than 54.100 mm so it bears on the outer ring and not on the inner. Get either wrong and the shoulder loads the wrong ring, which on a double row angular contact bearing means loading it through the balls. That is how a new bearing acquires brinell marks during installation and fails in weeks. Likewise the 1 mm maximum fillet radius: a generous radius left by a machinist on a shaft step will hold the inner ring off its seat, tilt it, and put the two ball rows out of alignment with each other.

The 3305 NR cross-reference

This record also carries the designation 3305 NR. The 3300 and 5300 series describe the same double row angular contact envelope under different numbering conventions, and NR conventionally denotes a snap-ring groove and snap ring in the outer ring. The Timken catalogue entry for 5305KG lists the cage as snap-in type and does not itself list an external snap ring, so we are presenting 3305 NR as a designation carried on this record and searched by buyers rather than as a confirmed statement that a snap ring is supplied with this unit. If a snap ring is essential to your installation, ask us to confirm against the actual part before ordering — we would rather check than have you find out on the bench.

Quantity and configuration

One bearing in stock. This is a complete bearing, not half of a matched pair: a double row angular contact unit locates the shaft in both directions on its own, so one bearing does the job that two opposed single-row bearings would.

Fitting notes

Press only on the ring being fitted — force must never pass through the ball complement from one ring to the other. Because this bearing sets its own internal geometry at manufacture, there is no endplay or preload to establish at assembly, which is precisely the labour saving it offers over an opposed pair. Do not attempt to adjust it with a setting nut.

Interchange guidance

Search forms include 5305KG, 5305-KG, 5305 KG, 5305K, 5305, 3305, 3305NR and 3305 NR. Timken absorbed the Fafnir bearing line, so machinery originally specified with Fafnir 5300-series bearings is supported by Timken part numbers today. Same-envelope equivalents are catalogued by MRC (now SKF) as 5305MG and 5305CG, by NSK as 5305, by NTN as 5305 and by Nachi as 5305 — all at 25 × 62 × 25.4 mm, but verify the contact angle before treating any of them as a drop-in for this one.