Converting the Hornby Mallard to Twin Track Sound and a Fixed Drawbar.


Parts Required:


X6211 - Drawbar or modify existing item.

X6113 - 4-pin Plug and Wires.

X9958 - 4-pin Socket.

X9333 - Small parts pack including various screws - optional.

X-various - Sound ready and/or fixed drawbar tenders.


Spares can easily be obtained from Hornby Spares Shop, Peter’s Spares, New Railway Modellers Shop, and other suppliers.


Reference:

Hornby A4 Service Sheets listed in the introduction.


Method:


Note: - You can save a lot of work if you can find a sound ready and/or fixed drawbar installed tender chassis - ref the above service sheets for details of associated part numbers.


1 Disconnect tender from loco by lifting the tender post from the powered drawbar.


2. Support loco body inverted in a suitable cradle. I made mine from a few pieces of polystyrene foam glued into a U-shape.


3. Remove the shouldered screw securing the drawbar to the fixed pony truck block - pictured. Unsolder the 2-wires from the drawbar. Retain the screw and drawbar for later.























4. Remove loco body by removing the single shouldered screw under the front bogie - swing bogie aside for access to the screw - pictured. Retain the screw for later. Lift the body at the front rotating about the cab and lift clear of the chassis and set aside in a safe place.
























5. Remove the tender body by first removing the rear fishtail coupling and then removing the screw concealed beneath - pictured. The tender lifts at the back (taking care not to damage any buffer beam details) and rotates about a lug at the front. Set aside the tender body for later.























6. Unsolder the speaker wires from the TTS speaker and set the speaker and enclosure aside for later.


7. Cover the decoder with a piece of heat shrink tube and plug the TTS decoder into the 8-pin socket on the loco chassis fixing the decoder on the block at the front of the chassis with double sided tape or similar.


8. Screw the new drawbar back onto the loco chassis using the old shouldered screw - pictured.























If you do not have a new X6211 drawbar to hand then carefully drill out the brass rivet holding the electrical contacts to the old drawbar and use that metal ink - pictured. Discard the electrical contacts.























9. Take the X6113 plug and tag the wires per the picture The 6-wheel tender is there to show the relative orientation of the plug and socket.























10. Solder the wires from the old drawbar to the 4-pin plug such that the left pickups attach to the left outer plug wire and the right wheel pickups attach to the right outer plug wire. Solder the speaker wires from the decoder to the inner pair of plug wires - it doesn't matter which way round they go.


11. Route the 4-pin plug under the pony truck frame and adjacent to the new drawbar. Make sure you have enough slack to allow movement when the plug is attached to the tender socket. Secure all loose wires to the loco chassis and motor with tape.


12. Modifying the tender. I removed the old tender post and replaced it with a bolt as shown in some of the illustrations, but in hindsight it would have been just as easy to leave it in situ so I will describe the conversion as if the post is left in situ. Unsolder the 2 pickup wires from the tender post - one top and one bottom.











































13. Remove the weight from the tender chassis by removing the 2 small countersunk screws, set aside for later.


14. Invert the tender chassis and remove the 2 screws securing the tender bottom which secures the wheels. Modify the tender bottom by cutting off as shown hatched in the illustration and also make a rectangular hole shown red in the chassis to accept the X9958 4-pin socket. Replace the wheels and tender bottom making sure you do not damage the wheel pickups.
























15. Solder the existing pickup wires to the outer contacts of the 4-pin socket taking care that left wheel pickups attach to the left outer contact and right wheel pickups attach to the right outer contact.


16. Solder 2 wires to the inner pair of contacts long enough to reach the speaker.


17. Secure the socket into the well in the tender chassis with glue and pack above it with plastic card or wood shims - arrowed. Make this thick enough such that the chassis weight will press on the shim to support the socket when plugging/unplugging.


Note: - There is a hole in the socket for a tiny self tapping screw to secure it but if you use this method ensure you use an insulating washer under the head to prevent shorting any contacts out. Such a screw on my tender would have fouled on the first axle, hence why I just glued the socket in.

























18. Refit the chassis weight and run the speaker wires as shown above via the front to the speaker. The speaker is mounted face up in an enclosure made from an old plastic Humbrol paint ‘tin’ cut down to suit. The enclosure tube is trimmed so that the speaker will clear the coal chute inside the tender body. Secure the enclosure to the chassis weight as shown with glue and fix the speaker into the enclosure using blu/white-tak mastic.


Note: - If you have a sound ready chassis then mount the speaker face down with its enclosure on top. Seal with mastic as before.


19. For the face up speaker installation only, drill 3mm diameter holes in the coal chute and 1mm diameter holes in the dummy coal load to allow sound to escape. Face down speakers allow sound to escape through holes in the chassis.























20. Invert the loco and tender and attach the 4-pin plug to the socket, locate the tender post onto the drawbar and set the loco/tender on the programming track. Attempt to read the decoder address - CV3. If all is OK then the installation wiring is OK and the decoder can be given its permanent address.


21. The loco and tender bodies can now be refitted and Mallard  returned to service.


RH/Feb-2017/v1.0







ROB’S RAILS            

Article 7 - Improving Mallard By Fitting a Fixed Drawbar And Installing TTS Sound                     

Hornby R2339 - Class A4 Mallard


This article is about improving Hornby’s DCC Ready Mallard by replacing the unreliable spring finger and clamp power transfer drawbar with a fixed drawbar and a 4-pin plug/socket arrangement.



Hornby ‘s Twin Track Sound (TTS) is also installed in the tender. At the time of the conversion  a Class A4 3-cylinder  sound was not available in TTS, so the similar Tornado sound module was used in lieu.


Reference should be made to Hornby Service Sheets numbers 256, 275, 350, 358 and 394 as applicable to your model and for new replacement parts.


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