It is suitable for use with a fixed transmission ratio on a road vehicle whose total loaded weight in Kg multiplied by its intended top speed in Km/h come to a figure of 30,000 or less, if run on 60V (or 72V, which is safe if the motor is not overdriven above the speed at which it runs without a load). If the weight multiplied by speed come to more than 30,000 it will be necessary to use a gearbox (and accept a large reduction of speed when climbing hills) or to use more than one motor. With a fixed transmission ratio it will be possible to maintain near full speed when climbing hills, provided that the battery can supply the necessary power.
(1) a motorcycle weighs 200 Kg loaded and is to have a top speed of 120 Km/h; multiplying these figures gives 24,000 and there should be no problems. The reduction ratio needed will be about 2.75:1 with typical size motorcycle wheels (3.00×17, 23 inches overall diameter including tyre) or 2:1 with typical scooter wheels (3.50×10, 17 inches diameter including tyre). These ratios can easily be obtained in a single stage with various types of chain or toothed belt. Note: motorcycle and scooter tyres have quite high rolling resistance and it would be much better to use radial-ply car tyres if you can obtain acceptable handling characteristics with them. They lack camber thrust when leaned from vertical and may need unusual steering geometry for best feel.
(2) a delivery van weighs 1500 Kg loaded and is to have a speed of 60 Km/h; this comes to 90,000 and with a fixed ratio it will be necessary to couple three motors (two might be adequate if the vehicle is not to be used in a hilly area) or to use a gearbox, with which the speed on the steepest hills will be reduced to 20 Km/h with one motor or 40 Km/h with two motors. With a fixed ratio, or in top gear with a gearbox, the overall reduction ratio needed will be about 5.7:1 with typical size small van wheels (155/80×13, approx. 23 inches diameter including tyre). (If the drive is through a gearbox the ratio between motor and gearbox will probably be about 1.5:1 reduction).
(3) a small car weighs 750 Kg loaded and is to have a speed of 80 Km/h; this comes to 60,000 and will be satisfactory with two motors and fixed ratio or with one motor and a gearbox. With a fixed ratio, or in top gear with a gearbox, the overall reduction ratio needed will be about 3.6:1 with typical size small car wheels (145/70×12, approx. 20 inches diameter including tyre). This ratio can be obtained in a single stage with various types of chain or toothed belt. (If the drive is through a gearbox the ratio between motor and gearbox will be quite close to 1:1).
For vehicles to be used on soft and/or steep ground (trials/motocross motorcycles, golf cars etc) the figure of 30,000, quoted above as the product of weight and speed, should be HALVED, and the weight used in the calculation should include any trailer to be towed. Take into account also the power required to drive any accessory, powered by the same motor, which may be fitted to the vehicle. The power for an accessory may be considered separately rather than added to the traction power if the accessory is one (such as a lifting platform) that is only worked with the vehicle stopped.
If the motor is to be run on less than 60V the figure of 30,000 should be reduced in proportion to the voltage. For example if the motor will be run on 12V the weight multiplied by speed should not exceed 6,000. Example: an electrically-assisted cycle-rickshaw has a loaded weight of 350 Kg and the motor, running on 12V, is to assist up to 15 Km/h; 350 x 15 = 5,250; the performance will be satisfactory. The reduction ratio needed will be about 5:1 with 28-inch wheels (used on Indian and Bangladeshi cycle rickshaws) or 3.5:1 with 20-inch wheels (used on some British cycle rickshaws). This can be obtained in a single stage with a small-pitch chain (25H duplex, 219, 8mm, 0.375 inch).
For light rail applications gradients and rolling resistance are much lower, and a single motor can pull greater weights. With a design maximum speed of 30 Km/h and maximum gradient of 2.5% (1 in 40) a single motor can pull a total train weight of four or five tonnes. With driving wheels 10 inches diameter the reduction ratio needed is about 5:1, which can be obtained in a single stage with 25H duplex chain (19 teeth on motor, 95 teeth on axle) with sufficient clearance for the axle sprocket to pass over points without fouling. The drive can be transmitted to additional axles by further chains with 1:1 ratio or by coupling rods. Four-wheeled (as opposed to bogie type) vehicles with a long wheelbase should be avoided, because they have high rolling resistance on curves.