Roller
Shells
The shell is fabricated from ERW 200 - 350 Range to AS1450, conveyor
tubing. Each shell end is machined to ensure concentricity to accept
the end discs and also maintain correct bearing clearance.
Roller
End Discs
The roller end discs are fabricated from hot rolled steel strip
to AS1594, HA4NP precision pressed in automatic presses, which ensures
bearing bores are sized accurately to house the bearing and also
ensure bearing housing is square to roller centre line. The roller
discs are 3mm CF welded in a special double-ended welding machine,
which gives a minimum of 70% weld penetration and ensures that the
shell tubing is concentric at the ends during the welding process,
thereby ensuring minimum run-out for the Tyton roller. Breather
holes are provided UNO, to prevent the roller breathing through
the bearing & seals when expansion & contraction occurs.
Roller
Shafts
All shafts are manufactured from low carbon-free cutting steel to
AS3679, Grade 300 and are normally machined from black bar which
gives larger shaft diameter between bearings with particular attention
given to the bearing seat machining and seal location, which is
finally centreless ground to tolerance. to give a precision bearing
fit.
Shaft
Retention
Shaft Retention is positive using seal circlips both ends to prevent
shell "walking off' the shaft. This allows the rollers to be installed
in the wing location either way without fear of movement.
Expansion
and Contraction
Expansion and Contraction is made possible by 0.25 maximum clearance
at the circlips, allowing the shaft to slide in the bearing inner
race without loading up the balls on the outer race. The outer race
is an interference fit in the housing to prevent bearing flogging
out the housing.
Idler
Roller Bearings
Tyton rollers are fitted with single row deep groove ball bearings
ZZ with a C3 or C4 internal clearance. We have selected these bearings
because they give up to ten minutes angular deflection in their
operation, coupled with even load distribution within each bearing
race.
Standard
Idler Roller Sealing
Seals (Inner): Integral with the ZZ bearing.
Seals (Outer):
The outer seal comprises a cartridge type seal which fills in the
"well area" (2 fixed and 2 rotating labyrinths can still be supplied
if required), followed by an outer water/dust line contact seal.
The outer seal is totally acceptable to the Department of Mineral
Resources for use in underground mines in NSW and Queensland.
It should be noted that the outer water/dust line contact seal can
cause high drag unless it is correctly put on. Tyton uses a special
setting dolly to ensure correct lip contact pressure.
Heavy
Duty Sealing
For extreme, heavy duty applications where dirty and/or abrasive
conditions are prevalent, a slurry seal is provided in conjunction
with a single labyrinth to the outer dust/water shield, for longer
life and greater durability.
Idler
Roller Lubrication
All bearings are completely factory filled with a lithium base grease,
specially formulated to minimise roller drag and give maximum resistance
to water wash out. Operating temperatures -20ºC to +130ºC, drop point 184°C.
Idler
Roller Surface Treatment
End discs are chemically degreased prior to welding to the tube,
and solvent cleaned prior to being given on coat of Tyton standard
red paint. Shells can be hot dipped galvanised and ends with corrosion
protective system on request.
Date
of Manufacture
Date of manufacture is embossed on one end of shaft.
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