A gearbox from a Meccano sports motor car, model 10.2. I’ve been asked about this gearbox and how to construct it, so here we go, also how it works. First of all we have reverse gear, like so. That’s the output shaft and this is the input shaft here. 25t gear going to a 19t idler going to a 25t, then over this this 19t and this 25t. This might look like one shaft in the middle, but the input shaft ends half way through this gear here. And the rest is the output. That’s why it can work independently. So that’s effectively 25:19 ratio. 1st gear we have 19t to 25t and 19t to 25t. That’s effectively 625:381. So that’s actually a lower gear than reverse gear which is slightly odd. We move that into neutral and move that over. Now this is 1:1. That 19t gear goes out to that 25t gear and then back to the 19t gear on the output shaft. So that’s 1:1. And finally top gear. We have a 25t gear there going to a 19t gear, that goes out to that 25t gear. So that’s a step up ratio and that’s 381:625. Beware you need a lot of short grub screws on this model or the gears jam against each other. Another thing is how to keep this lay shaft stationary while it’s not kept in place by the gear stick. The manual says put a 3/8″ bolt in that hole there and that will go against that rod gently. The shank of the bolt will go against that rod gently and you’re meant to use lock nutting to adjust that. I think that’s quite ridiculous. So what I’ve done is you have this fishplate here going to a threaded pin. There’s a compression spring on it. There’s also two washers to increase the pressure. The compression spring goes against the shaft and stops it from moving of its own free will. I think that’s a much better way to do it. The manual is very bad in this area. For this bolt it doesn’t say which hole to put it in. It just says it is in the top of the gearbox somewhere along here. This is effectively the top of the gearbox, like that he whole thing’s upside down. But anyway that’s how it works.