A four-row cylindrical roller bearing is incorporated into between the inner
peripheral
surface of a housing and the outer peripheral surface of a backup roller. A sensor
unit 7 is held in a portion of a collar disposed in the axial-direction
end portion of the four-row cylindrical roller bearing. The sensor unit comprises
a detect part for detecting temperatures and vibrations and a transmitter device
for transmitting signals, which are obtained after output signals taken out from
the detect part are processed, as radio signals. On a portion of a hold cover which
is a separate member from the collar, there is disposed a receive antenna which
is part of a receiver apparatus for receiving the radio signals transmitted by
the transmitter device.
