I recently spent six months living in India (July 23rd, 1998 to January 9th, 1999). During my stay there, I observed thousands of Autorickshaws. Autorickshaws have three wheels, two in the back and one in front, one driver's seat in front, and a seat that can hold two or three in the back. The canopy is made of canvas or sheet metal. I am in love with them. Note: All information presented here is gathered solely by my observations, and maybe a trip or two to the Bajaj Autorickshaw page, although they don't have much there.
There are three models of autorickshaws, which I call the Belt Drive (BD), Rear Axle (RA), and Rear Engine (RE, the official name). The two older models, BD and RA, have an engine located under the driver's seat. In the BD model, the rear wheels are driven by two belts that run down the side of the autorickshaw. The wheels are not connected by an axle, so if one belt snaps that wheel is no longer driven. The RA model has a rear axle driven by a perpendicular cam-shaft extending from underneath the driver's seat. The newest model, the RE, has the engine located over the rear axle, accessible from a rear hatch. The RE models are much quieter (when tuned properly) and less bumpy.
Steering an autorickshaw is accomplished through the handlebars mounted in front of the driver, almost exactly like a motorcycle or scooter. The left handle rotates with a twist of the wrist to change gears, with the clutch lever attached (it looks like a bicycle hand break). The right handle controls the throttle. On the right side is also a small panel of switches and buttons that control the windshield wiper (except on the ones with a hand driven wiper), the turn signals (rarely used in India), and the horn (used VERY often in India!).
Autorickshaws are seriously lacking in the fuel department. The fuel tank is unpressurized and does not seal with a gas pump nozzle. Also, the engine lubricant is mixed with the fuel. When refueling, the driver pours in some oil, then sticks a pipe in and starts the gas pumping. The tank is located on one side of the handlebars (in the BD and RA models), at a higher level than the engine. Since the tank is unpressurized, the gas would flow faster when the tank is full than when it was half full. To fix this potential problem, a small valve is located on the gas tube to adjust the gas flow.
The BD and RA models do not have any energy storage system; the headlights, brakelights, and turn signals are all run through a generator directly off the engine. Revving the engine causes all the lights to brighten. The RE has a 12V electronics system, including a battery, allowing steady lights, although no starter motor.
All models of autorickshaws have no starter motor; the driver either uses a pedal or a hand lever located to the left of the engine to get it turning, much like a lawnmower uses (except that they don't have gas-powered lawnmowers in India).