So my niece (about 40 lbs) finally got to test drive the cart. It appears to not have the torque to push itself through the grass. It has a 12t sprocket on the motor and a 60t on the axle. I know that's not a torque monster gear ratio but I figured it would be able to move through the grass still. Any other ideas? Maybe my el cheapo controller is the problem?
500 watt my1020 motor too weak to push cart in grass
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the 500W motor with the 5:1 gear ratio is the problem.
you need more like a 10:1 ratio with a motor that size, even just 40lbs (and another 50lbs for the kart most likely)
5:1 just wont do I can't recall the exact rpm the motor is rated for but I think it's around 3000 rpm;
you want that motor to not be 'faster' than maybe 6 to 7 mph on grass
based on the rpm and your wheelsize (which I don't know),
you can figure the ratio out exactly...
for now I'd say 10:1 should work
'sid
you need more like a 10:1 ratio with a motor that size, even just 40lbs (and another 50lbs for the kart most likely)
5:1 just wont do I can't recall the exact rpm the motor is rated for but I think it's around 3000 rpm;
you want that motor to not be 'faster' than maybe 6 to 7 mph on grass
based on the rpm and your wheelsize (which I don't know),
you can figure the ratio out exactly...
for now I'd say 10:1 should work
'sid
It's 2050 RPM per the tag. It probably doesn't go 5-6 mph now. I have 10" diameter tires now. The motor was essentially free and this was just a trial run at the whole electric thing so I'm not out much.
My guess is it would actually go faster if it was geared differently. As under no load that tire spins pretty darn fast.
I'll see what I can do about setting up a jackshaft but seeing as how I have a 3hp motor and I can get a 10t clutch for $40 it might be cheaper to switch it over to gas although that might be too fast and I'll need a jackshaft anyway
My guess is it would actually go faster if it was geared differently. As under no load that tire spins pretty darn fast.
I'll see what I can do about setting up a jackshaft but seeing as how I have a 3hp motor and I can get a 10t clutch for $40 it might be cheaper to switch it over to gas although that might be too fast and I'll need a jackshaft anyway
well it's slow because of the missing torque, not because of the low ratio now.
mathematically with 2050 rpm, 5:1 ratio and 10" wheels it should go ~12 mph.
and.. allow me to point out:
if you GEAR it to 6mph (as it should go 12 with 5:1) you'll end up with 10:1 ..
you can fab up a small jackshaft from parts you have (all you'd need is some pillow blocks perhaps)
Or, since that's a lightweight kart and a very small motor I even think a bicycle hub could withstand the abuse, either a front hub (as a pillow block replacement) with two sprockets welded/bolted to the collar, mounted to two simple tabs on the chassis.
or an internally geared rear hub for 'more speed on tarmac';
I can only guess, but I think it should withstand the 500W the motor can provide.
if you have one laying around it might be worth a try
but check it's reduction rate to dial it in... and don't buy one for this task;
it's a lightweight kart/kid and a small motor alright, but it might already pushing the limits of a bicycle part.
it MIGHT work.. but then again it might NOT, I don't know for sure.
'sid
mathematically with 2050 rpm, 5:1 ratio and 10" wheels it should go ~12 mph.
and.. allow me to point out:
if you GEAR it to 6mph (as it should go 12 with 5:1) you'll end up with 10:1 ..
you can fab up a small jackshaft from parts you have (all you'd need is some pillow blocks perhaps)
Or, since that's a lightweight kart and a very small motor I even think a bicycle hub could withstand the abuse, either a front hub (as a pillow block replacement) with two sprockets welded/bolted to the collar, mounted to two simple tabs on the chassis.
or an internally geared rear hub for 'more speed on tarmac';
I can only guess, but I think it should withstand the 500W the motor can provide.
if you have one laying around it might be worth a try
but check it's reduction rate to dial it in... and don't buy one for this task;
it's a lightweight kart/kid and a small motor alright, but it might already pushing the limits of a bicycle part.
it MIGHT work.. but then again it might NOT, I don't know for sure.
'sid
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10" tires are kind of big. Harbor freight sells those red tire/wheel combos for about $7 each. The tires are about 9" and narrow with good tread for grass.
I have similar motor, 36v 500w. I run a 11t front and 55t rear sprocket. When I run 18 volts, It goes about 9kmh with my kids on it both weighing 35kg combined and kart weighing about 25kg. When I run full voltage i can get just under 20kmh, on grass it has no problem pushing me around, let alone my kids. Maybe this helps
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