An electric phaeton is an early open passenger carriage driven by electric motors. The reference illustrated here uses frame-mounted motor pinions engaging internal gears on the driving wheels, with batteries beneath the seat and in the rear extension. The calculator converts two motor speeds, a reduction ratio and driving-wheel diameter into ideal wheel and road speeds.
Electric Phaeton Interactive Calculator
Explore an early open electric carriage with internal wheel gearing. Compare two motor speeds, reduction ratio and driving-wheel diameter while the drivetrain animates.
Equation Used
- Fixed motor and wheel axes with internal gearing.
- Common reduction ratio for both motor-speed conditions.
- Driving wheels roll without slip at the entered diameter.
- Tooth counts and vehicle proportions are illustrative.
Ideal no-slip speed conversion. No torque, traction, battery range or vehicle rating.
A frame-mounted motor drives an internal wheel gear
Hiscox movement 859 shows an open carriage with a tiller, raised seat, folded hood, spoked wheels and battery storage above the driving-wheel area. Its description specifies motors attached to a frame under the floor, with each motor pinion meshing with an internal spur gear on a driving wheel.
The larger detail makes that drive visible. The motor axis stays fixed relative to the chassis. The ring turns with the wheel; the pinion does not orbit like a planet gear. An internal mesh with these fixed axes turns both members in the same direction.
The animation moves the spokes and road reference marks consistently for forward travel in the left-facing side view. The smaller front wheel turns faster than the larger driving wheel for the same illustrative ground speed. The carriage stays centered so the mechanism remains visible.
The previous article described a nearly universal chain drive and attributed specific dimensions and failure behavior to that arrangement. Those claims did not describe the illustrated reference and have been replaced.
Compare two motor-speed conditions
Enter motor speeds A and B, the ratio of motor speed to driving-wheel speed, and the driving-wheel rolling diameter. The results are automatically ordered as lower and higher values if A exceeds B.
The replay varies smoothly between those two motor speeds. It runs at one hundredth the calculated angular speed for visibility. This varying speed is a demonstration, not a model of the historic controller or vehicle acceleration.
Wheel diameters and vehicle proportions in the side view are illustrative. Changing the diameter input changes the calculated distance per revolution; the drawing retains a readable framing.
From motor speed to road speed
For a motor-to-wheel reduction R, wheel speed is n_w=n_m/R. With wheel diameter D in inches, one wheel revolution travels πD inches under the no-slip assumption.
Ideal road speed in mph is n_wπD×60/63360. The factor 60 converts minutes to hours and 63360 converts inches to miles.
The lower and higher output values use min(A,B) and max(A,B). The reduction is common to both conditions. Doubling R halves wheel speed and road speed; doubling D doubles road speed without changing wheel rpm.
The displayed gear detail uses a 20-tooth pinion and N=20R ring teeth. Each available ratio step produces an integer N. These illustrative counts preserve the entered ratio; they are not measured tooth counts from the historic carriage.
Default 8:1 drive with 36-inch wheels
At motor speeds of 1000 and 1500 rpm with an 8:1 reduction, the driving wheels turn at 125 and 187.5 rpm. A 36-inch rolling diameter gives ideal road speeds of approximately 13.39 and 20.08 mph.
Changing the reduction to 10:1 gives 100 and 150 wheel rpm, or approximately 10.71 and 16.06 mph with the same diameter.
These are kinematic results, not verified performance figures for a named vehicle. They do not establish that its motor, battery, tires or chassis could sustain those conditions.
What speed ratios cannot predict
The calculator assumes the entered motor speeds can be maintained and the wheels roll without slip. It does not solve motor torque, grades, tire traction, battery current, range or acceleration.
The gear outlines are illustrative involutes without manufacturing root fillets. Shaft support, lubrication, tooth strength, backlash and interference require a separate design assessment. The drawing is not a fabrication plan.
The historical construction establishes the mechanism shown here. It does not establish a universal drivetrain, controller, range or speed for all vehicles sold as electric phaetons.
Electric phaeton questions
Why is there no chain in the new drawing?
The selected historical reference uses motor pinions and internal wheel gears. Other vehicles could use other transmissions.
Why do the pinion and ring turn in the same direction?
They form an internal gear mesh with fixed axes. This differs from an external pair, whose members turn in opposite directions.
Why does the front wheel turn faster?
The smaller wheel must make more revolutions to cover the same ground distance. The front-wheel size is illustrative; the calculator input is the driving-wheel diameter.
What happens if motor speed A is higher than B?
The result columns remain sorted as lower and higher speeds.
Does the higher result guarantee that road speed?
No. It is a no-slip kinematic conversion of the entered motor speed, reduction and wheel diameter.
Reference
- Gardner D. Hiscox, Mechanical Movements, Powers, Devices and Appliances (1901), printed page 222, movement 859 — electric phaeton side view, frame-mounted motors, internal wheel gears and battery placement.
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