Center axle of a bullwheel of passenger ropeway damaged after sudden stop
August 30, 2018
A mechanical reaction due to a sudden stop resulted in a significant torqueing force being applied to the haul rope tension system counterweight. The torqueing force caused multiple counterweight guides to fail and in turn cause the counterweight to tilt from its vertical position. The side loading to a bullwheel (due to the tilt) caused its axel to dislodge and become wedged between its channel mounts.
It is very likely that the torqueing forces to the counterweight and the failure of the roller guides to maintain the level position of the counterweight caused the side loading to the bullwheel. That in turn caused the flexing of the bullwheel channel mounts and caused the bullwheel axel to partially extract itself from the bore of the mounting channel and the bullwheel in turn tilting from it vertical position. A contributing factor very likely is that the counterweight guiding equipment and the bullwheel mounting channels were not providing adequate structural support in resisting the torque forces encountered during the emergency stop situation. The failure of one of the speed buttons used to slow the ropeway may have also contributed to the incident, given that delays using the rheostat allowed an emergency stop to occur, which caused excessive forces resulting in bullwheel damage. Another possible contributing factor is that the bullwheel channels were not designed to take excessive side loading which may occur during an emergency stop.