Human Electric Trike Thesis

Design of an electrically assisted human powered trike

Archive for September 21st, 2006

Received Stealth 1000 scooter

Posted by Bob Dold on Thursday, September 21, 2006 10:28 PM

I received the Schwinn Stealth 100 scooter today and assembled it and then took apart the rear wheel drivetrain to measure the motor/gearbox. I was able to remove the wheel ad motor assembly after removing 12 screws and then tapped the wheel off the gearbox shaft. the wheel was keyed to the 12 mm shaft with a 4mm key. After removing the motor guard/mount I weighed the assembly and took of the gearbox cover to inspect the gears. The gearbox uses a 10 tooth pinion, 58 tooth idler gear , and 68 tooth drive gear for an overall reduction of 6.8:1. The gears are packed with grease as shown in the picture below:

Several other Stealth 1000 owners posted  that they replaced the grease with oil to get a quieter geartrain, although I didn’t think it made much noise on my first test drives. The next picture shows the gearbox with the guard/mount removed, this assy weighs about 9 lbs.

After measuring the gearbox I created a SolidWorks model of it and started trying to fit it into the rear frame:

After evaluating various methods for getting the gearbox power to the rear wheel I settled on driving a 5 speed cassette mounted from the swingarm with a 14 tooth freewheel on the gearbox output shaft. With this driving the 38 tooth cog on the freewheel I will be able to gear down the motor enough to drive the 7 speed rear cassette at the same speed as the rider’s cadence.

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