Oil seals - Difference between R21 Single Lip & R23 Double Lip
An R21 type oil seal is a single lipped rubber coated seal with a metal inner. R21 type seals against internal media.
Alternate References: CB / SC / A / DG / 827N / BA / A103 / WA
An R23 type oil seal is a double lipped rubber coated seal with a metal inner. R23 type seals against internal media and offers an auxiliary lip which provides protection against dirt and dust.
Alternate References: CC / TC / AS / DGS / 827S / BASL / A104 / WAS
An R1 type oil seal is a totally metal enclosed seal.
Alternate References: C / SA / DB / SFK / 824N / B2 / B303 / WC
An R4 type oil seal is a single lipped metal cased seal.
Alternate References: B / SB / BB / DF / 822N / B1 / B207 / WB
An R5 type oil seal is a double lipped double sprung metal cased seal.
Alternate References: BK
An R6 type oil seal is a double lipped metal cased seal.
Alternate References: BC / TB / DFS / 822S / B1SL / B210 / WBS
An R12 type oil seal is a single lipped springless metal cased seal.
Alternate References: BD / WBO
An R22 type oil seal is a double lipped double sprung rubber coated seal with a metal inner.
Alternate References: CK / WAD
An R25 type oil seal is a single lipped springless seal.
Alternate References: CD / WAO