RMweb Gold rodent279 Posted October 25, 2011 RMweb Gold Share Posted October 25, 2011 The cylinders on a Hornby Hall are fairly crude by modern standards. Has anyone tried fitting cylinders off say an Airfix Prairie? I know in real life the Hall cyls were 1/2" dia. larger, but I think you'd get away with that in 4mm scale. cheers N Link to post Share on other sites More sharing options...
34theletterbetweenB&D Posted October 25, 2011 Share Posted October 25, 2011 No I haven't; but I have at various times used cylinders from class 'A' on a chassis from class 'B' when making something not available RTR. The usual style of the pair of cylinders being on a stretcher which sits on top of the chassis block makes such transfers relatively straightforward. There may be a need for packing, or cutting a locating slot in the chassis block to compensate for different mounting heights and fore and aft positioning; and it may be necessary to fill the slide bar mounting holes and make new ones, to adapt them to different slide bars. The 'half inch' is indeed neither here nor there in 4mm: many, many 4mm RTR models have 'shrunken' cylinders which are well underscale in one or more dimension to enable clearance for a bogie or pony truck to swing out on set track curves. This is likely to be an issue with the Hall, which has cylinders about 3'9" long over casings, and a 4'2" gap between the bogie tyres - the oversize flanges on an OO model are going to 'eat' all the clearance if a scale size bogie tyre diameter is used - so you will need to look into where the larger cylinders sit relative to the bogie wheel positions on your tightest layout curves to see what is possible. The RTR manufacturers cheerfully carve lumps out of cylinder heads and the inside of cylinder blocks to enable wheel clearance in order to have as near scale size cylinders as possible when seen in side view; it is alos not unknown for cylinders and carrying wheels to be slightly out of position to buy a little more space. Small compromises can yield the clearance without undue violence to appearance... Link to post Share on other sites More sharing options...
DS239 Posted October 25, 2011 Share Posted October 25, 2011 Hello Rodent! The usual upgrade for the Tri-ang/Hornby Hall,-as the parts are a straight swap,-was to fit the cylinders,slidebars,and con rod/crosshead assemblies from the Hornby Saint class.[i'd give you the part no.s,but I can't lay my hands on my book of service sheets at the moment] I wouldn't recommend using the Airfix 61xx Prairie type cylinders though,as the plastic slidebars are notoriously weak and prone to breakage.. Another option,and maybe easier to obtain,as more recently produced,would be the similar parts from the 28xx [tender drive version]which,IIRC,are the same apart from the cylinders,but you would have to check the clearances for mounting the cylinders as per 34C's advice above.. Link to post Share on other sites More sharing options...
Silver Sidelines Posted October 25, 2011 Share Posted October 25, 2011 Hello R279, You may be interested in the attached picture of a Hornby tender driven 28xx fitted with the cylinders and crosshead from a Mainline 43xx. I was not happy at the angle of the Hornby cylinders nor did I like the grey plastic piston and crosshead. As noted above a straight forward conversion building a copy of the Hornby Cylinder saddle using bits of plastic cut from a CD case. Regards Ray Link to post Share on other sites More sharing options...
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