| Author |
Message |
Admin (Admin)
Board Administrator
Username: Admin
Post Number: 19
Registered: 10-2004
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| Posted on Sunday, October 31, 2004 - 9:28 pm: |
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The reduction ratio you need depends on a number of variables: motor speed, vehicle speed and wheel diameter.
Ratio = (motor speed (rpm) x wheel diameter (m) x 0.117) / desired vehicle speed (mph)
Example: 6500 rpm motor, 215mm diameter wheel and a desired speed of 20 mph gives -
(6500 x 0.215 x 0.117) / 20
= 163.5/20
= 8.17:1
Once you have your ratio, you need to select suitable gears or sprockets to make up that ratio. Be aware that large ratios such as 8.17:1 are rather difficult to achieve in one stage of reduction and frequently require 2 or more stages. To find the overall reduction of multi-stage reduction, simply multiply each stage together. For example, to achieve 8.17:1, we would use say a 10 tooth sprocket on the motor driving a 40 tooth on an intermediate shaft (4:1). Also on the intermediate shaft would be a 20T sprocket drive a 40 tooth on the wheel axle (2:1). These combine to give 8:1 which is close to the desired 8.17:1.
Motor speeds are often quoted at off load and at nominal load. The value to choose depends on how hard your motor has to work to achieve the desired vehicle speed. Assuming you have an adequately sized motor, we tend to use a motor speed midway between the off load and nominal load figures. |
robin rice
Unregistered guest
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| Posted on Friday, December 8, 2006 - 10:41 pm: |
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hi i would like to mount a sproket on the shaft of a 2hp brigs & straton engine the size chain ime going to use is 3/8 i need a sproket with 11 or less teeth
the shaft has a 5/8 key way out put shaft |
Admin (Admin)
Board Administrator
Username: Admin
Post Number: 349
Registered: 10-2004
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| Posted on Sunday, December 10, 2006 - 9:14 pm: |
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Robin,
We stock a range of 3/8" sprockets including 8, 9, 10 & 11 teeth. See here where you can also download a data sheet that gives the sizes. All of our gears and sprockets are pilot bore so you will need to add your own keyway. We would not suggest using a sprocket smaller than 11 tooth with your 5/8" keyed shaft. |
robin rice
Unregistered guest
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| Posted on Monday, December 11, 2006 - 1:40 am: |
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thanks for the reply
is it posible to mount the sprokets to the wheel if i replace the bolts on the wheel with longer ones to go thro the gear
can you bore out a 3/8 12t sproket to 5/8 and tap a hole to put in a grub screw for the engin shaft and if you can how much would this cost and how hard is the steel the sprokes are made of |
Admin (Admin)
Board Administrator
Username: Admin
Post Number: 352
Registered: 10-2004
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| Posted on Monday, December 11, 2006 - 6:53 pm: |
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Robin,
It is quite common to mount larger size sprockets directly on the wheel using spacers and longer bolts. This has the advantage of not having to find some way of engaging the axle with the wheel, you can then use the internal bearings of the wheel assuming they have bearings.
Whilst we have the machinery to bore out and tap holes, we do not currently offer that facility as it would not be cost effective. The steel is not hardened so can be machined without too much difficulty. |
robin
Unregistered guest
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| Posted on Monday, December 11, 2006 - 7:04 pm: |
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ok thanks i will probabley get a 40t sproket from you soon and some chain ime going to get a clutch now if you want i will try to get some pics of it when i finish it. |
Admin (Admin)
Board Administrator
Username: Admin
Post Number: 353
Registered: 10-2004
|
| Posted on Monday, December 11, 2006 - 8:49 pm: |
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Robin,
We are always interested in seeing pics from customers especially if we can put them on the forum as it can be a help to other builders. |
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