AT Bearing 17x30x7mm RS chrome steel rubber shielded (6903-2rs)
These bearings are made from SAE 52100 chrome steel (GCr15), with carbon steel bearing cages. They have dual seals made from Nitrile Rubber bonded to SPCC steel shields, these seals contact both the inner and outer ring, for the best possible protection against dirt, dust and water, to offer you excellent wear and extreme durability. at the cost of slight extra friction. Chrome steel offers the best bending strength and fracture resistance of all the bearing materials, but it is not as hard (60-66 rockwell vs. 80-90 rockwell chart hardness) or long wearing as ceramic silicon nitride or silicon carbide ball bearings. For wheels etc these bearings are best, as they can take a good hit without shattering. Ceramics are best saved for gearboxes etc that won’t be exposed to direct impacts.
(For the lowest possible friction drag, but less dirt protection, use metal shielded bearings)
Bearings come pre-packed full of Kyodo Yushi Multemp SRL grease. Top quality, long performance life, wide temperature(-50°C to 150°C) range grease. It has anti-rust and noise suppresive properties, ideal for small sealed bearings. Lithium based.
(for best strength and corrosion resistance for salt water etc, use ceramic Si3N4 bearings)
Bearings manufactured from chrome steel can operate at continuous temperatures up to 120°C.
(for operating temps up to 800°C use ceramic Si3N4 bearings)