Classic UK Minitrix Models  -  Black 9F
Valve Gear

The valve gear comes complete with the pistons and plastic mouldings - unlike the Flyings Scotsman and Mallard. Here the right hand side is correctly assembled. The left hand side has the piston and conrod waiting to be reattached. Very fiddly.

Same components, from above.

I fold the eccentric rod forward to keep it out of the way while I gently manoevre the unit from the front to rest over the locating screw hole. The conrods need to be kept in roughly the position shown, otherwise the can splay out, and start sliding back down the piston rod.

A single black screw holds the assembly in place. The lamp housing is held in place by a single brass screw.

And the bulb can slot into place. Its actually quite fiddly with the housing in place to get the lip of the bulb behind the metal keeper and the rear contact of the bulb in front of the brass sprung tab.

The next operation has to be done with the loco on its side. Protect the gear on the other side from damage first. Use a screwdriver to raise the conrod so that the eccentric crank pin can be dropped into the hole at the end of the conrod.

Use another screwdriver to keep the conrod raised while you gently manoevre the square pin into position. The idea is to get the pin to join together the two half connecting rods.

The first screwdriver can now be used to raise the two short connecting rods and the main conrod. This leaves everything in roughly the right position, but leaves a gap so that you can see the hole in the wheel. Go back to the previos photo The arm of the eccentric crank needs to point towards the balance weight) the blanked off part of the wheel where there are no spokes. The rivet st the end of the platic crank needs to be almost over the centre of the wheel. Manoevre the plastic crank with your fingers. You will be able to feel when it is resting on the sqaure hole.

Here it is. The small screwdriver is applying very gentle pressure to the large part of the plastic crank to get the square peg just seated inside the square hole in the wheel. Remember that any pressure you apply here is also transmitted to the delicate valve gear underneath the loco.

Both sides fitted - loosely. The crank pins have yet to be pushed in properly. DOing this with the engine upright is much easier and much less likely to cause damage to the opposite side. Use the flat part of a small screwdriver to push the pin home. Do not squeeze both sides with your fingers. Fingers are too big and may cause other components to bend or break. Rivets can easily pop out of their holes with such mis-placed pressure.

I haven't mentioned the removal of the two sets of connecting rods. Here they are on a chassis which needs to be 'attended to'. Unlike the very tiny screws on the A1 and A4 locos, the devices which hold the conrol to the wheels are a simple push fit.

While you are looking at the picture, note that the copper contacts for the fron two wheels are not actually touching the wheel. This may make for some erratic running over points.

Maintaining Classic UK Minitrix Locos
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