RosiesBoss Posted February 10, 2016 Share Posted February 10, 2016 Introduction As noted by Sarahagain in post 4440 here: http://www.rmweb.co.uk/community/index.php?/topic/69535-great-british-locomotives/page-178, the GBL Britannia is a model based, not on either of the preserved locos, but on the 1960s-era Tri-ang model. Around 1998, I mildly upgraded one of the first-issue examples with new wheels, valve gear, name and number: More recently, I used the front bogie, pony truck and motor of a rough post-1961 Brit, together with parts from a Princess and A3 to assemble my version of Gordon: My spares box contained a good X04 motor from my Crownline conversion of an Ivatt 2MT into a BR Standard 2MT: In addition, I always maintain a good stock of loco, coach and wagon wheels – “just in case”…… I therefore had quite a few components on hand when my local newsagent received (in mid-Dec 2015) her usual stock (2!) of the then-latest GBL model: 70000 Britannia. Not surprisingly, I bought one and set it aside until other projects were complete. As received, it looked like this: Comparison with my existing model showed few differences from the 1960s-era Tri-ang model. One notable improvement was the closed tender axleboxes. Unfortunately, the pony truck axleboxes were still open, as on the Tri-ang model. Once I had stripped-down the GBL model, I was pleased to see that, unlike some of the other GBL models I had motorised (eg City of Truro and Caledonian Single), the front bogie and pony truck were moulded in plastic, with separate wheels which could be replaced easily. Comparison of the model’s dimensions and wheelbases with those provided in the excellent article in Model Railways (Jan 1972) gave the following information: Front bogie Bogie to Drivers Drivers Drivers to Truck Tri-ang and GBL 5’10.5” 6’3” 6’6”+6’6” 11’3” Actual 6’3” 5’6” 7’0”+7’0” 10’0” Clearly, motorisation of this model, using old Tri-ang components was not going to result in a highly accurate model. Instead, it was an opportunity to have a bit of fun using up some otherwise useless bits and pieces in the scrap-bin. I therefore resolved to avoid any unnecessary expenditure, while still assembling a presentable model. Parts List GBL Britannia Tri-ang Britannia chassis block, complete with cylinders, valve gear and Magnadhesion wheels Tri-ang-Hornby X04 motor and gear Romford 12mm dia wheels (for front bogie) Alan Gibson 13mm dia wheels (for pony truck) Mainline tender wheels 0.3mm dia phos bronze wire for handrails and pickups Turned brass handrail knobs 2mm dia “top-hat” bearings Brass strip and tube Stainless steel eyelets Humbrol enamel paints HMRS Pressfix lining Modelmaster cabside numbers Home-printed nameplates Chassis Minor changes were made to the diecast chassis block, to ensure a good fit at the rear (where it locates into the base of the backhead) and at the front (where it has to fit under the angle made by the front end of the footplate). A small hole was drilled to provide a screw point to locate into an existing pillar moulded inside the front of the GBL body. (This was later countersunk to improve clearance above the bogie.) Both the GBL bogie and pony truck were carefully dismantled and the solid wheels (on square-section axles!) removed and discarded. I decided to install two pairs of concentric brass tubes 3.2mm and 2.3mm dia, one inside the other, in the space vacated by the original bogie wheels. Each of these pairs then provided a good fit for some spare Alan Gibson 2mm dia axles, onto which I mounted spare Romford 12mm dia wheels. A couple of washers were then used to limit sideplay before I completed assembly. As the top of the bogie moulding was too high to fit under the Tri-ang chassis and still leave room for a swing-arm, some careful trimming was done to reduce that height. A small stainless steel eyelet (from the scrapbox) was then super-glued into the central hole, to reinforce the moulding. A brass swing-arm was then fabricated to locate the bogie correctly under the chassis and carefully bent to provide slight downward force, to compensate for the lack of mass in the plastic bogie frame. Given that the pony truck already had (non-prototypical) holes in the outer faces of the axleboxes, I deepened them with a 2mm drill and pressed in some plain brass bearings. After opening up the slots in the centre frame of the pony truck, I then installed a pair of Alan Gibson 13mm dia wheels on pinpoint axles. I then adjusted the brass bearings until they just met the axles without binding. They were then fixed in place with super glue. The outer holes in the axle boxes were filled later. The front hole was opened up and then reinforced with the same type of eyelet used in the front bogie. A brass bottom plate was then fabricated and superglued into place to strengthen the pony truck and facilitate transmission of tractive force from the chassis to the tender. Seen from the top, the plate is not visible. Once everything was assembled onto the chassis, it was tested and adjusted until all ran sweetly and reliably on Peco code 100 track, including live- and dead-frog points and a double-slip. Loco Body The body required few alterations to fit onto the Tri-ang chassis: Removal or shortening of internal plastic pillars Creation of two square holes in the base of the backhead, to fit to the rear of the chassis. The otherwise unaltered body was fitted to the rebuilt chassis and looked like this: It was now time to improve the details of the model. Moulded handrails and regulator rods were carefully removed. New brass handrail knobs were fitted (where required) and then strung with 0.3mm dia phosphor bronze wire. A new regulator rod assembly was fabricated from scrap brass sheet and phosphor bronze wire and then fitted. A new smokebox door dart was fabricated from a spare handrail knob and handrail wire and then mounted on the door. Moulded (plastic) safety valves were replaced by brass ones recovered from a battered Tri-ang Britannia body. Pony truck axleboxes were filled with automotive body filler. Tender The GBL tender chassis, having fixed wheels, was consigned to the scrapbox. A mounting pin which fouled the front axle was cut away. 2mm dia holes were drilled into the inside surfaces of all six axleboxes and brass top-hat bearings installed. Spare Mainline tender wheel assemblies, on pin-point axles, were then fitted and adjusted until they ran freely. Sheet lead ballast was glued to the floor, inside the body. The front (plastic) coupling pin was cut off and replaced with a 6BA bolt/nut. A Bachmann tension-lock coupling was glued to the rear of the tender, under the buffer beam. Moulded handrails were replaced, as for the loco body. Painting/Decorating I decided to renumber/rename the model as 70021 Morning Star, one of those sent new to the WR. This was the only one of that batch whose smoke deflector handrails were not removed and replaced by hand holds cut into the smoke deflectors. The loco (including chassis and wheels) was completely repainted with Humbrol enamels. Once these had cured, Pressfix lining was applied. Fine lines on the edge of the footplate were picked out with paint, using a fine sable brush. Cabside numbers and new nameplates were then fitted. When all transfer adhesives had completely dried, the model was varnished with Humbrol satin clear. Results The model runs as sweetly as she looks and can haul an 8-coach express with ease. Reflection This project aimed to motorise a static model using only components already to hand. This aim was achieved. The only cost was the purchase price of the GBL model: A$19.95 (under GBP10.00). I think I’ve achieved good value for money and now have another presentable BR(W) loco in my collection. Construction and finishing took just under 2 weeks of (spare) workshop time and provided an enjoyable exercise. Other Motorising Projects (http://www.rmweb.co.uk/community/index.php?/topic/67037-motorising-a-kitmaster-stirling-single/) http://www.rmweb.co.uk/community/index.php?/topic/70438-gwr-4-4-0s-on-carmarthen-junction/ http://www.rmweb.co.uk/community/index.php?/topic/59875-motorising-kitmaster-08/ Post #5 here: http://www.rmweb.co.uk/community/index.php?/topic/70550-carmarthen-junction-miscellena/ http://www.rmweb.co.uk/community/index.php?/topic/96216-motorise-gbl-city-of-truro/ http://www.rmweb.co.uk/community/index.php?/topic/102076-motorisation-of-gbl-caledonian-single-and-upgrading-of-her-coaches/ http://www.rmweb.co.uk/community/index.php?/topic/103776-motorise-gbl-stephenson%E2%80%99s-rocket/ References Model Railways (Jan 1972) Richard Derry et al.: “The Book of the BR Standards” (Irwell Press, 1997) Link to post Share on other sites More sharing options...
hallmodelspares Posted April 3, 2016 Share Posted April 3, 2016 An excellent project well done on using those parts supplied with the gbl model for the bogie and pony truck Link to post Share on other sites More sharing options...
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