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Unread 15-07-2009, 18:32
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Re: Help: Bevel Gear Mounted On CIM Shaft?

Quote:
Originally Posted by 854 bears View Post
I am doing a little off season project and experimenting with different ways to mount the drive motors to save space. My current design involves a set of spiral bevel gears, with one mounted directly onto the CIM shaft and the other on an axle supported on both ends. I don't have any experience using or mounting bevel gears, but during my research one source said that these type of gears puts a strong horizontal force on the shafts. All I am wondering is weather or not the CIM will be able to handle this force, or if I need to support the other end of its drive shaft. I don't have many specifics yet, but the gears will most likely be a 3:1 reduction.
PS. these plates will be CNC'd so everything will be precisely aligned, and built strong.

Any suggestions or thoughts will be greatly appreciated.

Thanks,
Team 854
Jim's already addressing the thrust issues with you, so I won't be addressing that here. My concern is the gear ratio. 3:1 is a little low unless you plan on using very small wheels. (I'm assuming direct drive from the second bevel gear).
Here is a good general guide line when working with the CIMs to make sure you don't overload them.

The KOP Toughbox is a 12.75:1 ration gearbox. In addition, the output and wheel sprockets give an additional 22:15 reduction. So, 12.75*(22/15)= 18.7:1 total reduction. Now, the KOP wheels are 6in. dia. Therefore, 3.1417*6= 18.8 in circumference.

One quick way to look at this is, design for approximately one revolution of the CIM for 1 inch travel. This is for a 150 LB. robot and it is only a rule of thumb.

Now, from experience, +/- 25% on these numbers works, but is not always optimal. Make sure you take into account what you goal is: Speed, Torque, Longevity etc.
Your milage may vary.
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