I have built five versions of a commuter trike prototype. To reconcile a having a car-height posture with a width that is narrow enough for bike paths, they have all been learnable. To be controlable on slippery surfaces they all had two-wheel drive. With a hub motor in front, the trikes are all-wheel-drive. All these vehicle have the designator EcoVia.
EV1 and EV4 had tadpole layouts with rear steering. Both suffered from instabilities. EV2 and EV3 were delta trikes. EV3 worked well enough that I use it to run errands in my neighborhood. EV3 used much of the hardware from EV2, which resulted in the design being overly complex.
When EV4 failed last fall, I decided to fix the obvious defects in EV3 and came up with EV5. Some of the hardware from EV3 and EV4 were reused in version five. Because of its large cargo capacity, EV5 has been renamed "E-Car-Go"
EV3 is shown below.
The EV3's rear wheels are mounted on beams that pivot to facilitate leaning. The pedals drive a jackshaft with a cassette in the middle and freewheels on the ends. Chains connect the freewheels to fixed cogs on the wheel axles on the other end of the wheel beams. The freewheels act as a positraction differential. The EV3 is not free-leaning. A lean lever allows for controlled leaning and there is a lean lock that can bias the lean lever force from free to being locked up. Steering is the under-seat type and leaning is controlled by a lever on the left side of the trike. Pulling back on the lever leans left and pushing on the lever leans right. Lean control is very intuitive. Below is the lean-lock that was repurposed from the EV3
Below is the E-Car-Go. The overall length if 80in., the width is 32" and the seat height is 20".
Numerous improvements have been made in the ECG.
1. To prevent wheel slip form the front motor wheel, a wider tire of 2.125" was substituted for the 1.35" wide rear tires
2. The intermediate bottom bracket, crankset, chainrings and chain where eliminated by connecting the cranks directly to the jackshaft with one chain and an idler.
3. A 1x12 drive was used having a gear range of 26 to 94gear inches.
4. A stiffer scissors joint with .625" bronze bushings was used to support the seat beam.
5. A bicycle shock absorber was substituted for the coil spring of the EV3. Changing the internal pressure of the shock allows for spring-rate adjustment to match rider and cargo weight.
6. The lean angle limit was increased from 17deg to 20 deg.
The lean control lever is shown below.
Leaning left.
Leaning right
7. Return springs were added to the lean lever
8. The brake modulator linkage, which equalizes rear-wheel braking to keep the trike moving straight when stopping has been improved. It is now symmetric insuring that the cable lengths for each brake are equal and have the same friction.
9. The construction of the wheel-beam assemblies has been simplified.
10. A second transport crate was added below the first crate. The crates have a volume of 1800cu.in.
Below is a sketch of an enclosed version of the ECG with the wheelbase extended to enlarge the cargo carrying capacity.
Hephaestus
8/7/2024
