Schaeffler North America


Marine Reduction Gear

Operating data

  • Input power: P = 5 475 kW
  • Input speed: 750 /min
  • Output speed:209 /min
  • Operating temperature: ca. 50 °C


  • High operational reliability
  • Good sealing with outboard drives
Bearing selection

Coupling shaft

The coupling shaft (upper right) is supported at the drive end by a spherical roller bearing 23248B.MB (1, locating bearing) and at the opposite end by a cylindrical roller bearing NU1056M (2, floating bearing). The shaft transmits only the torque. The bearings have to accommodate only the slight deadweights and minor gearwheel forces from a power take-off system. The bearing dimensions are determined by the design; as a result larger bearings are used than needed to accommodate the loads. Consequently, a life calculation is not required.

Input shaft

At the input shaft the radial loads from the gearing are accommodated by two spherical roller bearings 23248B.MB (3, 4). The thrust loads in the main sense of rotation during headway operation are separately accommodated by a spherical roller thrust bearing 29434E (5). The bearing 23248B.MB (4) on the left side also accommodates the smaller axial loads in the opposite direction. It is adjusted against the spherical roller thrust bearing with a slight clearance and preloaded by springs. The preload ensures that the thrust bearing rollers do not lift off the raceways when the load changes but keep rolling without slippage. The housing washer of the spherical roller thrust bearing is not radially supported in the housing to ensure that this bearing can transmit no radial loads.

Output shaft

At the output shaft, radial and axial loads are accommodated separately. The radial loads are accommodated by two spherical roller bearings 23068MB (6). In the locating bearing position at the output end a spherical roller thrust bearing 29464E (7) accommodates the difference from the propeller thrust during headway operation and the axial tooth loads. The smaller axial loads during sternway operation are taken up by the smaller spherical roller thrust bearing 29364E (8). These two thrust bearings are also adjusted against each other with a slight axial clearance, preloaded by springs and not radially supported in the housing.


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