Building a double Fairlie chassis in 009
Jan van Mourik (2001)
Some photos can be enlarged and contain additional information.
My double Fairlie chassis was built using two 0-4-0 Fleischmann N gauge steam locomotives as shown in photo 1.
Photo 1. The Fleischmann steam loco, of which we need two for this project.
After taking off the loco bodies, the motors are removed. The bodies will be needed later, so we put them aside for a while. The next job is taking the mechanisms apart completely, and cutting off the motor mount and rear coupler pocket in one piece, from both chassis blocks. One of these also will be needed later. The worms are removed from the motor shafts and put in a safe place as they are easily lost. The photos below show a motor and motor mount from various angles.
Photos 2. The motor and motor mount taken from one of the mechanisms.
Thus, we are left with two sawn-off chassis blocks with wormwheel, axles, motion, cylinders and front coupler.
From the loco bodies a great deal has to be removed: the cab, the boiler fittings etc., and after further cutting down we have an arrow-shaped metal block with the threaded hole needed to bolt the chassis to it. Part of the tanks of the original loco body are left in place (see photos 3 and 4).
Photo 3. The remains of one loco chassis with the cut down body attached..
The cut down water tanks are needed for strength and to protect the chokes and capacitor fitted to the current collectors. From above we can now see the wormwheel.
Photo 4. The bogies ready for further work. Enlarge to show explanation.
Using two pieces of pertinax PC board and one of the sawn-off motor mounts we assemble a frame which is a tight fit around the motor. The electric feed to the sprung carbon brush housings on the motor is also carried by the PC board.
Photo 5, showing the motor and motor mount glued to apiece of pertinax. To the pertinax a steel frame is soldered which carries the attached worm shaft bearings. The new worm shafts are made from ordinary nails.
Photo 5 clearly shows the inner motor frame. The motor has been fitted with extended shafts which was realised as follows. After removing the worm I put the motor with its rear bearing on a vice the jaws of which were set slightly open to accommodate the motor shaft. Using a hammer I gave a sharp tap on the other end of the shaft, moving this through the collector and rotor. This is a risky operation as the motor may be damaged, but it survived all right. If it won't work, we always can use the other motor! The shaft extenders are fitted to the shaft ends using plastic bushes or sleeves that, together with the flywheel, came from the junk box. This proved to contain old insulated wheels from an H0 gauge locomotive which were ideal for the job. From one wheel I removed the flange, using a file, from the other I pressed out the plastic bush and used this as a connecting sleeve. It is impossible to fit a flywheel to the rear of the motor as this would obscure the fixing screws.
The extender shafts are two nails of correct diameter which have a corrugation about 3 to 5mm from the head which can be used to fix the worms. In the pictures the shafts and worms still have to be aligned correctly below the pivot holes.
Photo 6. View of the steel carrying frame.
The carrying frame as shown in photos 5 and 6 was made of 1mm steel sheet and consists of two identical parts that were bent to shape and soldered to the inner (motor) frame made of pertinax. In order to fit this assembly to the bogies, two small frames had to be made as shown to the left in fig. 1. These were fitted to the bogie top using an M2 bolt in a specially drilled and threaded hole.
Fig. 1 - to the right a flat layout sketch of half a steel frame, to the left the smaller frame which is fitted to the bogie top. Both of these need to be made up in pairs.
Fig. 2 - a half-frame after having been bent, with the bearing hole to the left and the pivot hole to the top.
Fig. 3. Assembly of the half-frame, which sinks through the elongated hole in the auxiliary frame which goes to the bogie top. The large screw is M3, the smaller is M2. The diagram also shows the worm and the extended shaft (the extension bush has been omitted).
The diagrams are not to scale and only serve to clarify the text and the photos. Photos 5 and 6 do not yet show the auxiliary frame which goes to the bogie top as this had not yet been made at the time.
The worm needs to be exactly in line with the pivot which consists of an M3 screw passed through the holes in the half-frame and the auxiliary frame, being locked up with a nut fixed with superglue.
Photo 8 showing details of the pivot and the auxiliary frame fitted to the bogie top.
Some freedom of movement is needed at the pivot as the bogies will have to adapt to the track. The worm wheel is driven by the worm on the extender shafts, but despite this the bogies can swing to a considerable degree without locking the transmission. The chassis can pass through 19cm radius curves without problem.
Photo 8 - Overview of the components of the chassis.
Photo 9 - Detail shots of the chassis and the wiring.
Photo 10 - all components built together, resulting in a smooth-running double Fairlie chassis.
Click on the icon for a video recording (4 seconds, 800kB).
Finally, some remarks to be made about the chassis.
Still to be done is scratchbuilding a suitable freelance body which needs to look like a Ffestiniog Fairlie to some extent.
A prototype Fairlie photographed outside Boston Lodge, courtesy M.A.Polet.
