
the gearbox bearings when direct drive top gear is
engaged. It is possible that some load may be imposed
on the mainshaft rear bearing, but this arises from
propeller shaft operation.
When the indirect gears are selected, it is then that
the separating and end thrust forces acting on the
helical constant-mesh gears, and whichever other pair
of gears happens to be engaged, have to be taken into
account. This means that there will be combined radial
and axial loading on both the primary shaft bearing and
the mainshaft rear bearing, together with a radial load
on the mainshaft front or spigot bearing. Although the
layshaft bearings will be subjecte ...