Modifying the Heljan Bogie Drive

This section describes the operations involved in modifying the drive unit for one bogie.

Removing bogie sideframes Unplug the cosmetic sideframes from the two mounting studs on each side of the drive unit.

Top cover Cut the pivot hole tag from the top cover of the drive unit and clip the top cover back on to the drive unit.

Removal of Undertray Spring off the lower cover from the drive unit. Remove the three wheelsets and put them to one side.

Use a relatively beefy screwdriver to unclip the four clips on one side of the undertray, working from one end to the other. The tray may then be lifted away.

Coupler pocket If you do not wish to retain the coupler pocket, the two halves of the drive unit may now be separated slightly and the coupler pocket removed. Cut off the mounting eye and forked spring mouldings associated with the coupler.

Axle spacer mouldings Reduce the depth of the arched shaped spacer mouldings around the end axle holes of the drive unit. The overall width should be no greater than about 10.5mm.

Sideframe mounts Remove the pickup contact strips from the sideframe support studs and then trim back the studs to leave about 1 - 1.5mm projecting from the drive unit.

Undertray Remove the moulded bumps from the lower surface of the undertray; in many cases they can be taken down flush without making a hole in the moulding, but it does not matter too much either way.

Take a little of the thickness off the outer ends of the undertray moulding.

Modified drive unit Enlarge the central axle slot to give at least 1mm clearance around the central axle.

This photo shows the completed modifications to the drive unit.