Bachmann 10-Wheeler Battery Conversion

The Starting Point

I came upon a Bachmann Big Hauler battery operated train set via the well known auction site, and my goal was the purchase of the track, the bonus was the wagons, accessories and the loco, which was described as “non-working”.  So my plan is to convert this 49 MHz radio controlled loco that uses 6 “D” cells, and has basic sound to 2.4 GHz, LiPo powered with a MLS sound card.

My loco and tender were similar to these, all plastic, including the wheels and motion. The batteries had been left inside and leaked, and the loco had to be stripped down to remove these corroded batteries.

A New Chassis

with all the negative points for the original chassis I decided that a replacement chassis with metal wheels and metal motion would be required, a new 81099 chassis was located and bought.

After an initial test on a rolling road using track power it was time to disconnect the power from the wheels to the motor.  On removing the bottom I decided that rather than remove all the wipers (which I considered would not cause too much drag) just the connections to the wiper would be removed.

As can be seen in the photo disconnection of the power from the wheels is just the removal of two plugs, allowing all the contacts to remain in place, so reversal should be simple if required.

The track power pick up plugs were pulled through the chassis and tied of to prevent short circuit.

The chassis came with two sliding switches in the harness, one to switch polarity and one for smoke.  I have no plans to utilise either of these, so these were also tied off.

With the chassis electrics tidied up, a trial fit of the body was carried out, and this generally fitted well, however, as the output connections at the rear of the new chassis were different to the new chassis the opening had to be enlarged to allow access to the two sockets and the switch.

NOTE: The left hand socket feeds power to the tender, but for me will provide the ESC power input to the loco, the right hand socket is the “chuff” sensor to the sound card, and is planned to be used, the switch switches on/off the “chuff” sensor.

Powering The Chassis

As per my Stainz and trailing wagon conversions I am using a plug-in curcuit board to keep wire splicing to a minimum and fault diagnosis easy.

All of this will fit in the tender when complete, the photo shows the original speaker and a trail run on a rolling road.

The power switch/charging socket/LED 2 repeater module is mounted in a raised platform

The raised platform is fitted on to the tender chassis, and with the tender body fitted all the components of the module can be accessed under the rear panel.

Adding Weight To The Chassis

As the donor loco was originally the battery operated model, the loco does not have a weight, the 6 D cell batteries providing the weight.  However the new chassis has mounting points for the standard weight, and after making enquires about the optimal weight of the loco for traction (6 lbs) work began on the weight.

The plan was to produce a plastic card base and side supports, fill with diving weights and secure with 2 part polyurethane resin.

With the new weight fitted to the bare chassis, a trial was required.  The R/C equipment was temporally fitted to the tender, and coupled to the loco and the two Bachmann Jackson Sharpe coaches were connected.

The consist was then trundled up my steepest gradient (1:25)  which it managed without any issue.  So one more stage down and on with the next.

Bodywork

On the trial fit of the loco body on the new chassis, the only real issue was the tanks forward on the chassis, when positioned in their original holes would not sit correctly as the front of the tanks interfered with the the cylinder chests.  My original consideration was to remove the front part of the tank, however after a little investigation I found moving the holes would work.  A small infill was added to the footplate, and new holes drilled.  A trial run found that the cross-head now caught the tank banding, so a small vee was filed in it, and as this is on the underside, it will not show.

Painting and Re-assembly

The tender, loco body, cab and larger ancillary items have been cleaned, primed and and black gloss top coat applied.  The TDF name on the tender and number nine on the cab, and finally a coat of gloss varnish applied.  I don’t think I need to go into detail as all of this is the standard practice for using “rattle cans”

Detailing has begun, and one of the main components so far in “handrail knobs”, these have been used with 1/16″ brass rod to replace all the hand rails on the tender, cab and loco body.

However closer inspection of the chimney and domes reveals that the primer is still visible on the loco body, so a quick strip of the details added and a re-spray will be in order.

The Finishing Line

The last of the detailing is now complete, which started with the quick re-spray over of the the visible primer.

External pipes, brass bell, Westinghouse pump, and front stanchions, also loco crew fitted.

1 mm clear acrylic sheet was used to glaze all the windows.

A test run has been carried out, but a video will follow in the warmer weather.

Main Suppliers used for the components:

  • G-Bits
  • Chalk Garden Rail
  • Micron Radio Control
  • CPC Farnel
  • Dream Steam
  • Garden Rail Outlet
  • Cathy’s Castings
  • S & D Models

Components used:

  • Bachmann 81099 chassis
  • Bachmann 31.0 mm metal wheel sets (tender)
  • Deltang Rx66b receiver
  • Deltang Tx 22X transmitter
  • Overlander 2200 mAh 35c 3S LiPo battery
  • Toggle switch/charge module (Micron own)
  • MyLocoSound steam sound card
  • Brass Bell
  • Westinghouse pump casting
  • Loco crew