
FINAL DRIVES AND REAR AXLES 335
ments for the fully floating hubs of some heavy vehicles
is an interference-fit wear sleeve. This fits over the end
of the axle tube and thus permits easy replacement of
the axle sealing surface whenever the oil seal requires
renewing.
20.7
HEAVY-VEHICLE REAR AXLES
Single-speed double-reduction axles
The development of higher-speed engines for heavy
vehicles, which began in the early 1950s in America and
then spread elsewhere, generally dictated proportion-
ally lower (numerically higher) axle ratios. These were
necessary to provide a greater final reduction in speed
between the engine and road wheels in direc ...