RANS S-20 RAVEN
TEXT MANUAL
9/01/2013
01A-03
IMPORTANT INFORMATION:
MATCO Mfg wheels using tapered roller bearings are equipped with
Timken bearings utilizing integrated grease seals on the bearing cone to
ensure the longest possible life. The torqueing procedure for bearings with
these type seals is different than for tapered roller bearings without them.
A common torqueing technique for bearings
without integrated seals
is to
tighten the axle nut until the wheel stops spinning freely and then back off
to the nearest locking feature.
THIS TECHNIQUE WILL NOT WORK ON
A BEARING WITH AN INTEGRATED SEAL.
The reason for a different
torqueing technique is that the grease seal produces some drag and
makes the wheel feel somewhat stiff when rotated. Reducing the axle nut
torque until the wheel spins freely will allow the grease seal and the
bearing cone to improperly rotate with the wheel (the cone must not rotate
relative to the axle). The higher rolling drag is completely normal for this
bearing and allows for longer bearing life since the seal will keep most
contaminants out. Timken specification state, for example, that the two
1.25 inch tapered roller bearing used on the WE51 will produce 18-26 inch
pounds of torque (drag) when properly installed. A light coating of grease
on the seal will help reduce the drag on initial installation. The drag will
also reduce after the bearings have been installed and the seal relaxes in
the bore. It is important that the axle nut torque be sufficient to keep the
seal from rotating with the wheel. With the bearings cleaned, dried,
greased, and inserted in the wheel, the axle nut should be tightened until
all play is out of the assembly. Rotate the wheel back and forth while
tightening the nut to help seat the bearings. When all play is out of the
assembly, and the wheel rotates freely, tighten to the next castle slot and
insert the cotter pin. The rubber seal on the tapered roller bearing will
remain stationary while the wheel rotates around it. If the seal is spinning
on the axle, the nut should be tightened further until the seal stops
spinning with the wheel.
13.
Apply Thread Sealant to the threads of the brake fitting and install the
fitting into the caliper. The fitting should face upward.
14.
During Final Assembly, route the brake line from the Fuselage bulkhead
fitting, down the Gear Leg, to the Brake Assembly.
NOTE: The brake line
will press into the groove machined into the aft side of the Gear Leg.
