Heljan Class 35: Pickups and Power

There are several options for arranging power pickups and you may have your own preference. However, as space is rather constrained in this bogie design, we describe here the method that we came up with and applied successfully.

Remove the undertrays and wheelsets from the drive unit.

Pickup mountings Using a razor or piercing saw, make a vertical cut, flush with the side of the drive unit, about one-third to half way down through the residual stubs of each of the sideframe mounting pillars.

Mark a vertical centreline on each side of each drive unit, mid way between the stubs. Mark two further vertical lines 4.5mm either side of the centreline.

Degrease thoroughly the phosphor bronze pickup strips, the sides of the drive unit around and between the stubs of the sideframe mounting pillars, and the top face of the drive unit under the drive coupling. Roughen those areas of the drive unit by scoring with a sharp knife.

Twisting the pickup strips Twist the ends of the pickup strips through 90°, so that the dimples in the extreme ends are facing downwards.

Hold the main part of the strip in a hand vice or pliers and use a further pair of pliers, about 1.5mm away, to make the bend in a single action. Take care, as the strip will quickly become brittle if overworked.

Glueing pickup strips in place Bend the ends of the strips outwards, and ensure that the bases of the strips, over and between the mounting points, are flat.

Using quick-set epoxy, glue the strips into place, locating them in the sawn slots at the bases of the sideframe pillar stubs. Avoid glueing in the area between the vertical marks (not as in this photo).

Allow time for the glue to set and gather strength.

Copper wire bus bar Unsolder the wires from the pickup strips.

Take a length of single-core copper wire (fairly hefty - say 0.9mm core), strip it and bend into a squared U shape, the base of the U being wide enough to span over the distance between the vertical marks. Make a further pair of 90° bends near the base of the U, so that the base of the U will rest on the top face of the drive unit, under the drive coupling, whilst its legs rest against the side of the unit, over the phosphor bronze strip.

Tin the copper wire, hold it in position and solder it to the phosphor bronze strip.

Bus bar, top view Put a good fillet of quick-set epoxy around the wire on the sides and top of the unit, again avoiding the area between the vertical marks (at the sides) and also avoiding glueing the two halves of the unit together.

Allow time for the glue to set and gather strength.

PB strip cut away Cut through the phosphor bronze strip just outside of each vertical mark. Remove the portion of strip, and any stray glue, from between the marks.

Solder the pickup leads on to the copper wire or strips, at the outer ends of the units, adjacent to the worm gear towers. (Refer to your note of which wire goes to which side).

Adjusting pickups Offer up the wheelsets into the units, ensuring that they are in the correct slots and orientations, and adjust the pick up strips to bear lightly on the wheel flanges.

Finished drive unit, from underneath Re-fit the undertrays to the drive units, securing the wheelsets in place.