|
|
|
![]() |
|
|||||||
|
||||||||
![]() |
| Thread Tools | Rate Thread | Display Modes |
|
#16
|
|||||
|
|||||
|
Re: 2.5" CIM Motor stops when climbing
Unfortunately I don't think so. You need a bigger reduction for this than you can get from just a chain reduction. Look into a versaplanetary or a banebots planetary. Shipping may be an issue so id try to contact some local teams to see if they have anything laying around.
|
|
#17
|
||||
|
||||
|
Re: 2.5" CIM Motor stops when climbing
Quote:
The biggest ratio you can get practically with sprockets (at least easily available ones) is about a 5:1. Now that said, at a 5:1 ratio, if you double the number of motors running it (like adding a second CIM to the opposite side of the system) that 5:1 ratio would work just fine. Ideally though you would want a proper gearbox that will get you closer to that 9:1 ratio. Last edited by cbale2000 : 04-02-2017 at 16:30. |
|
#18
|
||||
|
||||
|
Re: 2.5" CIM Motor stops when climbing
Quote:
|
|
#19
|
|||
|
|||
|
Re: 2.5" CIM Motor stops when climbing
Actually no. Not yet.
|
|
#20
|
||||
|
||||
|
Re: 2.5" CIM Motor stops when climbing
I have enough power to climb a hill on my bicycle... but I cannot do it quickly. I have to do it very slowly. I must shift to a lower gear ratio in order to do it without getting too tired.
Similarly, the CIM motor has enough power to lift your robot, but it cannot do it quickly. It must be (as we say in the US) "geared down". That means, you will have to use a small gear on the motor shaft to drive a shaft with a larger gear. That same shaft may need a small gear driving another shaft with another large gear. Eventually, the power will be "geared down" enough to lift your robot. A gearbox is another way to do it. Another thing that could help is to wind your rope onto a smaller diameter. That too will have the effect of "gearing down" the CIM. Good luck, and I hope we have been helpful to you! Last edited by chapman1 : 04-02-2017 at 17:24. |
|
#21
|
||||
|
||||
|
Re: 2.5" CIM Motor stops when climbing
Quote:
|
|
#22
|
||||
|
||||
|
Re: 2.5" CIM Motor stops when climbing
If obtaining or making gear is box out of question, consider 2 stages of chain reduction - 5:1 each?
|
|
#23
|
||||
|
||||
|
Re: 2.5" CIM Motor stops when climbing
Quote:
You are going to have a hard time doing more than a 3:1 per stage with shaft driven sprockets, since the large tooth counts tend to be plate sprockets. Not sure what size sprockets are easily available there. |
|
#24
|
||||
|
||||
|
Re: 2.5" CIM Motor stops when climbing
Quote:
If you don't mind the slower speed a 15:1 will give a more comfortable margin. |
|
#25
|
|||||
|
|||||
|
Re: 2.5" CIM Motor stops when climbing
To sort of cut through what has been posted -- a single CIM has PLENTY of power to execute a robot climb in a very few seconds. The key factors are -- did you gear down enough so that you can wind up on your drum diameter? How much will your effective drum diameter increase as your rope wraps on top of itself? As a reference point, 3946 is planning to wind some 3/8" line on a 1/2" shaft with a 12.75:1 reduction. Our biggest problem appears to be keeping the rope centered on the robot. Larger diameters will require more aggressive gearing, but will be less susceptible to a wrap or two of line.
|
|
#26
|
||||
|
||||
|
Re: 2.5" CIM Motor stops when climbing
Quote:
|
|
#27
|
||||
|
||||
|
Re: 2.5" CIM Motor stops when climbing
Didn't see that response.
In that case would depend on how that specific cord wraps up. The example I gave was based on my own testing and estimates, individual results may vary. Quote:
|
|
#28
|
|||||
|
|||||
|
Re: 2.5" CIM Motor stops when climbing
Maximum robot mass = 70 kg. Maximum robot weight = 70 x 9.8 = 690 N.
Effective winch radius = (winch diameter + rope diameter) / 2 = 2.25 cm. Winch torque needed to lift robot = 2.25 x 690 = 1550 N-cm = 15.5 N-m. At maximum power, CIM motor torque = 1.2 N-m. [Note: climbing is fastest at maximum power.] Climbing time = lift height x robot weight / winch power = 1 meter x 690 N / 330 W = 2.1 sec. Gear ratio required = 15.5 / 1.2 = 13:1. Andymark Toughbox with 12.75:1 ratio is in stock as I type this. All of the above calculations are simplified by neglecting fricition losses. A real robot will require more climbing time. Last edited by Richard Wallace : 05-02-2017 at 07:28. Reason: Climbing time calculation |
|
#29
|
|||
|
|||
|
Re: 2.5" CIM Motor stops when climbing
You've described very well. Thank you all. I'll inform you about the advancements.
|
|
#30
|
|||
|
|||
|
Re: 2.5" CIM Motor stops when climbing
If we can find a gearbox, which model do we need for CIM motor? 15:1 Ratio
Thank you. |
![]() |
| Thread Tools | |
| Display Modes | Rate This Thread |
|
|