This research investigated bearing failures in a spur gear cutter bar used in the
agricultural equipment sector for cutting forage crops. The cutter bar is under
consideration by Case-New Holland (CNH) for use in their equipment. The primary
focus of this investigation was to develop and test a real time monitoring system to
monitor the health of the bearings during operation and alert the operator of the location
of a pending bearing failure. This system uses temperature as the monitoring parameter
and does not estimate the remaining useful life after the initial failure mode has been
detected. The temperature profile of interest is that just before catastrophic failure and
based on that is used to alert the operator.
Causes of bearing failure within the cutter bar are also investigated theoretically
to determine the effect that they would have on bearing life. Both cutter bar bending and
bearing misalignment were analyzed from a theoretical perspective. Bending of the
cutter bar was determined to not have a detrimental effect on the contact stresses within
the bearings and thus no shortening of bearing life. Bearing alignment is a critical factor
in bearing condition as excessive misalignment creates high contact stresses reducing the
useful life. The gear train and bearings are retained between two steel halves creating a
case, and to prevent excessive misalignment the case halves cannot shift by more than
0.47 ±0.04 mm relative to the vertical axis of each bearing mount.
Additional testing determined that operating the cutter bar on a hill has no effect on bearing life and that oil temperature can be used to monitor the correct amount of oil in the cutter bar.
University of Minnesota M.S. thesis. August 2010. Major: Biosystems and agricultural Engineering. Advisor: Dr. Jonathan Chaplin. 1 computer file (PDF); xiv, 189 pages, appendices A-C. Ill. (some col.)
Pommeranz, Garrett Vernon.
Condition based monitoring of gearbox transmission elements in a spur gear cutter bar..
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