Installing TrainBoss™
Axle Sensors

Axle Sensor in place

In this is the finished scene, the Axle Sensor LED peers over the farside railhead, with the back of the Infrared Sensor on this side of the rails.

The camera is just below the top of the railheads, which makes the LED appear lower than the railhead — which would be improper alignment.

This article explains how to install Axle Sensors with track already in place. These step-by-step photos supplement Step 4 in Section 1 of the TrainBoss™ Talking Defect Detector and TrainBoss™ Displaying Defect Detector Product Manuals.

Step numbers correspond to the installation steps in both product manuals.

Step-By-Step Installation

Axle Sensor Installation

Axle Sensor Installation (Figure 1 in the Product Manual)

One or more ties will need to be removed, depending upon your model railroad scale.

Note that for O Scale and larger, only one wheel is sensed.

Steps 4a - 4d

Steps 4a - 4d

Power down your track and remove the required number of ties as shown above.

Clear any balast or scenery materials from around the installation area.

Drill a 1/4" hole beneath the track and across the roadbed as shown.

Steps 4e - 4f

Steps 4e - 4f

Cut with a knife to extend the hole to the roadbed surface.

Using the Axle Sensor as a guide, mark and drill a 3/16" hole for the wires through the roadbed.

(A little cracked plaster is easy to fix.)

Step 4g

Step 4g

With the LED leading, slide the Axle Sensor under the rails (or just rail for O Scale and larger).

Step 4h

Step 4h

Thread the wires through the 3/16" hole.

Axle Sensor Alignment

After bending the LED to face the Infrared Sensor (Step 4i), you are ready to align the Axle Sensor. This step is critical to ensure correct axle counting by your TrainBoss™ Defect Detector.

Begin by aligning the Axle Sensor horizontally. The faces of the LED and Infrared Sensor should be equal distances from their respective railheads. This step is critical to ensure correct axle counting by your TrainBoss™ Defect Detector.

Check that all of your railcars and engines pass without interference.

Axle Sensor Alignment

Axle Sensor Alignment (Figure 1 in the Product Manual)

LED Too Low

If either LED or Infrared Sensor are too low, the Infrared Beam will not completely cross the railheads and the Axle Sensor will miscount — typically too low.

Best Alignment

The full faces of both the LED and the Infrared Sensor are just above the railheads.

(The face of the Infrared Sensor is the small round blister just above the midpoint of this square component.)

Infrared Sensor Too High

If either LED or Infrared Sensor are too high, low hanging details on engines and railcars will cut the Infrared Beam, resulting in an incorrect and too high axle count.

Best Alignment

Best Alignment

Note the complete face of the LED is visible and appears to be resting on the farside railhead.

Be sure you are looking exactly across the tops of both railheads when making this check.

Using the above photograph and figures as guides, now align the Axle Sensor vertically.

Flat toothpicks make excellent shims for this purpose.

Test your installation as described in Section 5 of the Product Manuals. Glue your Axle Sensor in place when you are satisfied with its accuracy.

WARNING: Give water based glues and wetting agents at least 48 hours to thoroughly dry before connecting your Axle Sensors to the Defect Detector. This is especially important after using water-diluted white glue for ballasting. If you connect your Defect Detector too soon, you may experience buzzing from your speaker, or worse.

If you find an occasional high axle count:

  1. Divide the offending train in half and run each segment by the Axle Sensor again.
  2. Take the half with the high count, divide it in half, and test each of these halves (now quarters of the original) to find the one with the high count.
  3. Repeat dividing and testing until you find the offending car (or cars). A bit of flash on the bottom of a truck sideframe or a low center sill or brake gear will usually be the culprit.
Step 6

Here is the finished installation.

To hid the Axle Sensor further, thin a tie and glue it on top of the Axle Sensor circuit board. A splash of ballast will finish the job.