Classic UK Minitrix Models  -  Britannia


Remove the loco body. A single screw on the top holds this in place. Remove it, lift the cab slightly and move the entire body forward slightly. The body should lift off. Note that there is nothing to keep the valve gear in place. Remove the weight (which may have a locating pin on the top. If so, the weight will require a little manipulation for the pin to clear the hole.

Remove the valve gear. To do this, you need to prise out the plastic crank from the centre wheel. It is easily damaged, so take care. Position a small (not too small) screwdriver blade between the conrod - which connects the centre wheel to the piston, and the coupling rod which connects all 3 wheels. Twist the blade. The leverage is applied to the metal rods which act to distribute the pressure, rather than to the plastic crank. See photo.

The conrod and the piston rod are now free to fall off. Remove the screw from the centre red moulding (you will have to gently move the wire to one side). Place the valve gear safely to one side, and make sure that you have the piston pin and the conrod.

Remove the plastic crank from the centre wheel on the other side, and place both valve gear assemblies somewhere safe.

The complete valve gear assembly, correctly assembled. Note that the conrod will fall off the plastic peg, and then slide down the round piston rod. The piston rod is also free to fall out of the hole on the plastic slider. That slider is extremely fragile. When handling the valve gear it is extremely important that it experiences no force. This may happen if the piston rod slides out at an angle, and is then knocked. Best to note how it is assembled, and remove the piston pin and con rod.

Note how the plastic mouldings are fitted and place both halves and the screw somewhere safe. (For reference, the right hand moulding in this picture was on the chassis. The tag on the valve gear was placed in the half slot, and the other piece fitted on top, trapping the valve gear in place.

Remove the coupling rod which connects all 3 wheels. Note that the rod is held in place by a screw in the front and rear drive wheels. The screw has a hexagonal head and requires a 2mm socket. Fine pliers will work, with care, but expect them to damage the head of the screw - as can be seen in this photo. Note that the rod has tabs above each of the holes, and these face upwards.

The screws are extremely tiny. As soon as they have been removed, place them somewhere safe. They are not easy to replace.

The wheels are held in with 2 screws. The baseplate in the picture is not the original - it is a home made version to replace the original. The screw at the left end (front) is acting as a pin, which on the original is moulded onto the top side of the plate.

With the plate removed, the 3 drive wheels are free to fall out. The front bogie is also free and the rear bogie will be attached to the tender. Note that the front bogie has a shaped brass strip on the top side, and that this may fall off. Place the 2 screws, the 3 drive wheels and the front bogie (and strip) somewhere safe.

Remove the screws holding the motor in place. These are at the rear of the cab, and are countersunk. The screw is very short and could be lost easily. A magnetic screwdriver helps, but remember to place them safely out of the way.

The motor itself slides out of its housing to the left of the engine (towards you in the photo), but it is first necessary to unsolder the wires. Move to one side any part of the wire whose insulation may touch the iron, and have a small pair of pliers handy to pull away the soldered connection as soon as the solder gets hot. Note that there is a plastic sleeve on the spring which retains the bushes (light green in this photo). You may wish to slide this back before heating the connection to prevent it from melting.

The other side of the loco has a blue wire which connects to a capacitor, the tab for the drive wheel contacts and the front lamp. My Mallard has no capacitor, but this photo from a Flying Scotsman (same chassis) shows where it fits. My Flying Scotsman doesn't have a front light bulb though ! This blue lead needs to be disconnected from the tab. It is possible towork around this if you don't fancy soldering it up again afterwards.

The wiring from the Mallard. On the right, the soldered tab for the drive wheel contacts. On the left, the soldered tab for the front lamp. There never was a capacitor on my Mallard, although the hole in the frame upright seems to have a blob of solder in it. But I've had it from new, so I'm not sure what has happened there. It makes soldering that much easier.

The tender cover is held in place by a single screw in between the pairs of wheels on the underside.

Remove the cover and the weight(s). The circuit board is retained be a screw at one end and a tag which slots into the frame at the other end. Remove the screw and GENTLY lift the circuit board............

......keeping an eye on the tiny spring that is at the right hand end of this photo. On the Flying Scotsman, and perhaps later model Mallards, there is a red moulding which provides insulation between the chassis and the spring. The spring transmits power from the right hand track, through the axle and pickups, throught thie spring and on to the motor via the green wire.

Note the soldered joints, and the need to keep this flat. They go face down onto the chassis, separated and insulated by a thin piece of insulating material. Any sharp wires protrucing through the solder would perforate the insulation. If you intend to replace the wire, you will need to desolder the joints. Be careful to leave the choke coil in place, or else remove it and keep it safe.

The wheel bodies can be removed. These are a special screw which allows the brass collectors to fit over the screw head and rest on a flange on the screw. Removing these can be tricky, and replacing them is also a little awkward. However, if the copper isn't springing against the axle adequately to make a proper connection, then they need to be removed, cleaned, bent to provide the necessary contact and replaced. However, when I took my screws out, the rear one cracked the red plastic insulating moulding. The screw would not then stay in place to maintain the electrical contact. I had to create another solution see the cleaning and repairing section. The point is - ask yourself whether or not you need to remove these screws.

  And that's it. You now have a box full of bits, a chassis, and a body. Time now to clean it up and make any repairs that are necessary.

Maintaining Classic UK Minitrix Locos
The Minitrix trademark is currently owned by Märklin Inc.  Gebr. Märklin & Cie. GmbH, Stuttgarter Straβe 55-57, D-73033 Göppingen, Baden-Württemberg

Website ©2002-2018