Take a look at some of the Scag spindle* features.
Bearings -
Scag spindles utilize a matched set of tapered roller bearings.
Tapered roller bearings have 50% more load capacity than ball
bearings. The taper angles allow the bearing to handle a combination
of radial and thrust loads, unlike a ball bearing.
Housing - Cast iron spindle housing. Increased shock load strength over aluminum
housings. Super strong to take the everyday abuses of mowing. In 2004,
Scag spindle housings were upgraded to an even thicker mounting flange,
increasing strength by 163%!
Hardened
spindle shaft 1-1/8" diameter. Extra
large diameter, hardened spindle shaft provides superior strength.
Key groove is cut into shaft for solid pulley mounting.
Grease
fitting. Top-mounted for quick
and easy greasing. No need to crawl under the cutter deck.
Grease
relief valve . Special relief
poppet valve ensures that "over-greasing" and damaging a seal is impossible,
even with powered grease guns. The valve is spring loaded to prevent
debris from entering the housing, unlike "weep holes".
Blade
bolt mounting hole. Cutter
blade retaining bolt travels through the center of the shaft. Under
extreme impact, only the bolt may need to be replaced, not the entire
spindle assembly. The thru-bolt design also allows you to change blades
without altering the proper preload (150 ft. lbs.) on the tapered roller
bearings.