Buffer switches are used to determine if the Buffer has returned to within 1/2 in of full extension on all cars with Gas Spring-Return Oil Buffers. They must return to full extension within 90 seconds. The Exception is Type C Buffers. Here the Auxiliary Safety Plank has Switches to prevent movement if the Plank is out of level by more than a 1/2 inch, and another Switch to prevent movement if the Buffer is compressed more than 10% of it's stroke. Also another switch if the Oil Level is below minimum. All good reasons that there are only a few Type C Buffers around. I have only seen Type C's on Montgomery Elevators.
