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SupportOld Support Forum Archive - Info OnlyTransmission (Bearings, gears, sprockets & wheels)Gears / Sprockets / ChainGear reductions and mounting gears / sprockets to shafts
SupportOld Support Forum Archive - Info OnlyTransmission (Bearings, gears, sprockets & wheels)Gears / Sprockets / ChainGear reductions and mounting gears / sprockets to shafts
Gear reductions and mounting gears / sprockets to shafts
| Technobots FAQ » Transmission (Bearings, gears, sprockets & wheels) » Gears / Sprockets / Chain » Gear reductions and mounting gears / sprockets to shafts | « Previous Next » |
| Author | Message | ||
| Simon Morrell (Simonmorrell) Member Username: Simonmorrell Post Number: 1 Registered: 4-2006 |
Hi I just bought two of your Bosch 750W motors for a project I'm working on. I'll be using these to drive two separate driving wheels on my model. I want to acheive a maximum wheel rotation of 200rpm (about 6mph on 10" wheels) I think that I need to put a 15t gear on the motor output and drive a shaft with a 50t gear on it (3.33:1 reduction). This shaft would have an 11t kart sprocket connected to a 65t sprocket on the wheel axle (5.9:1 reduction). I think this is correct but I'm struggling to figure out how to do all this. My questions are these:- 1) If you wanted to reduce the Bosch rotation by 20:1, what method would you suggest? 2) If I used the gears I saw on your web site, how would I secure them to a shaft? One needs to secure to the motor output, the other to the shaft with the sprocket on Thanks in advance for your advice Best regards Simon Morrell |
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| Admin (Admin) Board Administrator Username: Admin Post Number: 168 Registered: 10-2004 |
Hi Simon, 200 rpm will give some 6mph on 10" wheels as you say. The Bosch motor on 24V will have a nominal speed of 3300 rpm at 750W output power but best to assume 3600 rpm as you should not need full power to maintain crusing speed. This gives a ratio of 18:1. Personally I favour to use spur gearboxes but will require machining facilities. 18:1 in one stage of reduction is very large, in fact this is far greater than can be achieved with Technobots sprockets or gears. Two stages as you suggest is far more practical but the difficulty here is diameter of the lay shaft. In your example you would have a 11t and a 50t on the same shaft with their difering bore diameters causing problems. Stepped shafts are possible. Depending on your project, it is not uncommon to see spur gearboxes, 2 stage chain reduction or a single stage spur gearbox followed by a single stage of chain reduction. As I say, I favour spur gearboxes but the more common way is chain and sprockets. Depending on the project, you would need 3/8" or 1/2" sprockets or MOD 1.5 or MOD 2 gears (although we have seen MOD 1 used very successfully by one user) All of our gears and sprockets are supplied as 'blanks' so you can choose your own fixing method. Tapped holes with grub screws are popular on the motor drive gear but best to pin the gears on the axles using taper pins or similar. If you have accessto a milling machine, keyways offer the best performance. Others may have different views or solutions which may be worthy of consideration. We even know that some weld the gears onto shafts (makes maintenance a challenge!!). Regards Paul |
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| Ben Buchanan Unregistered guest |
Hi, I am really interested in using your 24V motor, 11 and 40 tooth sprockets and a chain to drive my 20mm drive shaft in my project. My question is what is the best method of fixing the 40tooth sprocket to my drive shaft. I understand that I can drill out the pilot hole to 20mm so that it will fi on my drive shaft, but how can I get it keyed? Is there a service you can recommened? Any help appreciated. |
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| Admin (Admin) Board Administrator Username: Admin Post Number: 982 Registered: 10-2004 |
Ben, A look in your local yellow pages may reveal a machine shop that can cut keyways but it is quite specialised. You can always drill through the sprocket boss and shaft and insert a pin / dowel all the way through. You can cut a keyway easily in the shaft with a milling machine, the slot in the sprocket is not so easy. I have cut slots in gears using a milling machine and then filing square, takes a while but certainly works. Here is a link to a picture where the keyways were made in this way http://www.technobots.co.uk/M2XT/M2XT-Home/M2XT_Build/Transmission/Gearbox_Inter nal.jpg |
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| John Dunn Unregistered guest |
Hi, I need a pair of drive gears that at a 5:1 ratio, smaller gear on a 10mm shaft and larger gear on 20mm shaft. Both gears need to have hubs and allen keys to fix gear to shaft. I am looking at your Mod 2 steel spur gear range but I cannot tell from the pictures whether they have bosses and allen screws on hubs to allow me to secure them to the shafts? If they do not have hubs and allen screws, which of your other gear ranges might be suitable? |
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| Admin (Admin) Board Administrator Username: Admin Post Number: 1132 Registered: 10-2004 |
John, The gear description should state the boss diameter but all of our MOD 2 gears are pilot bore which means the method of shaft fixing is down to you. You will need to drill and tap your own fixings. The reason we do this is that it allows the customer to choose their own fixing method such as dowel, taper, keyway etc.. This applies to most of our gears except for a range of brass hub nylon gears which are much too small for your application. It is very easy to drill and tap the boss, if you require advice on tap size, let us know what gears you need and we will advise. |
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