FixVault

Oil Pump

The pump within the transmission is an externally toothed gear pump. The engine drives it via a shaft through the hollow primary pulley shaft. The pump shaft is splined to the planet carrier, which always runs at engine speed  . System pressure reaches 40 bar. The oil pressure is used both for controlling the transmission hydraulically, and for lubrication purposes.

Fig 1: Oil Pump Assembly
G04724782Courtesy of BMW OF NORTH AMERICA, INC.