What calculator tab on the JVN would we use to calculate our winch needs? Or is there a better way to calculate the gearbox needed for our winch?
Depending on the use case, the linear mechanism tab or rotary mechanism tab.
Ok we used the linear tab, but what should we be looking for? We plan to use a CIM motor and a single gearbox. I’m not sure what numbers we should be looking for as being “good” for a winch.
Last night we used the JVN calculator for our winch and after plugging in the numbers for the gearbox we had installed and the pulley diameter and our time to go 24 inches was about 20 seconds. When we looked at the stall load, it was 7,900 lbs, which was way over-kill. We dropped the gearbox ratio down until we got to the loaded travel distance time we wanted and then made sure the current draw per motor was not too high and the stall load was not too low.
I’m going to suggest using my design spreadsheet for calculations like this. The mechanism calculator should let you determine the proper motor(s) and gear ratio for your application.
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I’m trying out your sheet, but when I change the linear feet per second to anything greater than 1 with 10 volts and a 154lb load I get errors.
Can you send a screenshot? If you don’t have enough motor power it may be physically impossible for the selected motor(s) to move that weight at that speed.
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As you can see in the max power column, the fastest one CIM at 10V can lift 154 lbs on a 1” radius is 0.89 ft/s. The motor simply doesn’t have the power to lift it any faster, no matter what gear ratio you put. If you need a faster speed, you’ll need to add more motors (or switch to a more powerful motor)
Ok, so using .89 as our speed, it shows a 16.65:1 ratio, with a stall load of 332lbs and a current of 51.8 amps. Changing to .85 ft/sec gives us a ratio of almost 20:1, stall load of 397, and current of 43.8. What would your recommendation be? 16:1, 20:1, or bigger?
It’s hard to say really without understanding your mechanism and use case. If you’re going to be lifting this weight for a long time, you probably want the current to be below 40A so you don’t trip your breakers. If it’s only for a second or two and you want the extra speed, you can go a bit over that.
It’s for the endgame climb
I would not recommend having your mechanism draw 40 amps or more for the endgame climb. Keep in mind that climbs also will occur using a less-than-full battery, lowering the voltage and raising the current. That said I think 10 volts is too conservative…
I would design your mechanism differently than how you are doing it. Start with the motor you are willing to use, pick a gear ratio in the JVN calculator that gets you below 40 amps under load, then read out the time to actuate the mechanism (also shown on the sheet) and see if that is acceptable to you. If it is not, you need to add more power (additional motors).
A 36:1 ratio gives us a current of 25 amps and a speed of .6 ft/s, which I think we can live with considering we only need to wind about 4 feet of cable max, which is about 6.5 seconds.
This seems like it would definitely be safe for your application. You can always iterate between events to make it faster if you need to.
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