PortaTree Eliminator Asphalt Tracks - Manual (Page 6)

beam height using a triangle as performed on the stage beam. When you are working on the prestage
beam height, it is best to block or shut off the stage beam light source or reflector. You must now
establish the prestage beam height and test the rollout with a rollout wheel. When you have the rollout
set at 12 inches, you can now test the distance between the prestage and stage beams.
Unblock the stage beam light source and make sure that there is no crosstalk between the
prestage and stage photo detectors. This is done by going over near the light sources or reflectors and
blocking each light source separately to make sure neither light source has an effect on the other. We
usually take a 4 inch square object and move it through the beams at the light sources or reflectors. This
will immediately tell if there is any crosstalk.
The rollout wheel should now be placed in the racing groove and should be rolled into the
prestage and stage beams. Each time a prestage light or stage light goes on or off on the christmas tree,
make a mark on the track surface with chalk. Roll in - - prestage on - - mark track - - roll in - - stage on
- - mark track - - roll in - - prestage off - - mark track - - roll in - - stage off - - mark track. Take your
ruler and measure the distance between marks and you should have 7 inches - - 5 inches - - 7 inches. If
you have done your previous work correctly, then these measurements should be obtained.
The layout of your entire track can now begin. The starting line is the most difficult to setup and must
be square and true with the rest of the track and photo cell layout. If you know where your stage beam
line is located due to past surveying, then the rest of your track can be measured per our track layout
drawing.