688-2Z Bearings | McMaster-Carr

Smoother than smooth—the balls inside these bearings roll nearly friction-free. You’ll often find them on rapidly rotating parts, from the whirring chuck on a power drill to the spinning shaft on an electric motor.

Shielded—The balls are covered just enough to keep out large particles while allowing air to pass through and dissipate heat.

Corrosion-Resistant 440C Stainless Steel—Combine the strength of steel with the corrosion resistance of stainless steel. These bearings won't degrade from water or mild chemicals, such as the ammonia in cleaning solutions. However, they'll weaken when exposed to salt water and harsh chemicals, such as bleach.

ABEC Rating—Bearings with an ABEC rating meet industry tolerance standards established by the Annular Bearing Engineers Committee (ABEC). They're rated on a scale from 1 to 9. The higher the rating, the tighter the tolerance. Bearings rated ABEC 1 or 3 are precise enough for most applications. If your application consistently runs at high speeds or requires high accuracy, consider bearings rated ABEC 5 or higher, since they generate less friction and heat.

							Temp. Range, ° F
	For Shaft Dia., mm	For Housing ID, mm	Wd., mm	ABEC Rating	Dynamic Radial Load Cap., lb.	Max. Rotation Speed, rpm	Min.	Max.	Inner Ring Type	Bearing Trade No.		Each
Shielded







				Corrosion-Resistant 440C Stainless Steel

				8	16	5	5	280	43,000	-40	240	Standard	688-2Z	7804K117	00000

Flanged Ball Bearings

Shielded

Install these bearings inside a housing and they won't budge. The flange presses against the housing wall, so vibration and other sudden forces parallel to the shaft (thrust loads) won't knock them off-kilter.

Shielded—The balls are covered just enough to keep out large particles while allowing air to pass through and dissipate heat.

Steel—Strong and wear resistant. However, these bearings are best for dry environments since moisture will cause them to rust.

				Flange, mm					Temp. Range, ° F
	For Shaft Dia., mm	For Housing ID, mm	Wd., mm	OD	Thk.	ABEC Rating	Dynamic Radial Load Cap., lb.	Max. Rotation Speed, rpm	Min.	Max.	Inner Ring Type	Bearing Trade No.		Each
Shielded







				Steel

				8	16	5	18	1.1	3	280	40,000	-50	300	Standard	688-2Z	57155K625	000000




						Corrosion-Resistant 440C Stainless Steel

						8	16	5	18	1.1	3	220	40,000	-50	300	Standard	688-2Z	57155K626	00000


						8	16	5	18	1.1	5	280	43,000	-65	250	Standard	688-2Z	7804K147	0000