Gear ratios and torque

Technical discussion on converting internal combustion to electric
Post Reply
Izabarack
Noobie
Posts: 5
Joined: Sun, 22 Jul 2018, 16:27

Gear ratios and torque

Post by Izabarack » Thu, 11 Oct 2018, 14:02

I hope this is simple and a search did not convince me. Am about to install 1800 Watt 48 Volt Brushless motor turning 9 tooth cog, in a small quad EV conversion. Chain drive is intended to be to a 74 tooth cog on the rear axle. So a 8.22:1 step down. Ignoring losses, am I correct in thinking that 8 times the motor delivered torque will drive the rear axle?

Iza

User avatar
jonescg
Senior Member
Posts: 2393
Joined: Thu, 21 Jan 2010, 23:05
Real Name: Chris Jones
Location: Perth, WA.

Re: Gear ratios and torque

Post by jonescg » Thu, 11 Oct 2018, 14:21

Yep, that's correct. You are of course limited by speed now, so it won't be a particularly fast mover, but should move OK.
AEVA National Secretary, WA branch vice-chair

Izabarack
Noobie
Posts: 5
Joined: Sun, 22 Jul 2018, 16:27

Re: Gear ratios and torque

Post by Izabarack » Thu, 11 Oct 2018, 14:30

Thanks for the confirmation, just checking. The chain drive is based on relatively small T8F spec so I do need to check what that size will handle. The project is intended of kids to use on a bush block and I don't want them going fast anyway.

Iza

User avatar
Richo
Senior Member
Posts: 3360
Joined: Mon, 16 Jun 2008, 00:19
Real Name: Richard
Location: Perth, WA

Re: Gear ratios and torque

Post by Richo » Fri, 12 Oct 2018, 12:31

4500RPM -> 547RPM
3.8Nm -> 31.4Nm

I see some buggies get about 35kph, stand up scooters 55kph.
Help prevent road rage - get outta my way! Blasphemy is a swear word. Magnetic North is a south Pole.

Izabarack
Noobie
Posts: 5
Joined: Sun, 22 Jul 2018, 16:27

Re: Gear ratios and torque

Post by Izabarack » Fri, 12 Oct 2018, 18:21

Those torque numbers are useful to me, Ta. Raw numbers I have produced suggest I should get about 38 Kph top at those ratios and rolling circ of the driven wheel. I'm on a steep part of the learning curve but having fun.

Post Reply