Quadvelo: Finally, after 50 Years, a Worthy Sucessor to the Pedicar

Many of my small number of followers know of my fascination for the 1973 Pedicar that made its debut in the US during the gas crisis. The Pedicar was revolutionary, but unfortunately, less than 20 units were ever built.

The post below goes into depth on the Pedicar's construction.

   https://lefthandedcyclist.blogspot.com/2012/04/pedicar-technology.html

The arrival of the Pedicar started my quest to design my own all-weather pedal-powered commuter vehicle, and I was presumptuous enough to think I could improve on the Pedicar.

My list of requirements for the design is listed below

1.The vehicle should have three or more wheels for stability on slippery surfaces.
2. It should place the rider's head at the height of a typical automobile.
3. It should be narrow enough to comfortably fit in a bike lane. I can be more specific on this. It should fit between barriers spaced 36" apart, so assume a maximal width of 34".
4. It should not overturn when cornering. Assume a tipping resistance of .7 gee.
4. It should be enclosed to protect the rider from the elements.
5. And for traction on slippery surfaces, it should drive at least two wheels.

The Pedicar met all the requirements, except the width being approx. 36" wide. In current dollars the cost was $3620. 

The Pedicar's technical failing was its linear pedal drive. The pedal levers pulled chains that ran over freewheels. This resulted in a constant torque at the wheels. A freewheel on each half-axle acted as a posi-traction differential. It had five forward speeds and a very impressive reverse gear. Braking was with twin discs on the rear wheels. 

It was 82" long with a 58" wheelbase and weighed 125lb. 

The chassis was an "I" shaped aluminum weldment with the long section supporting two crossbeams. There was no formal suspension and shocks were absorbed by the twisting of the central section.

The Quadvelo is 34", 98" long with a wheelbase of 69". It weighs 210lb. with doors and battery. It has a number of similarities to the Pedicar.

 Both used four 20" wheels. The Quadvelo's chassis is made up of a "T" shaped aluminum weldment. Perpendicular carbon-fiber leaf springs support the front wheels at the front of the "T" and longitudinal leaf springs support a transverse beam that, in turn supports the rear wheel axles. The seat can slide along the longitudinal leg of the "T". 

The seat's angles are adjustable and the handlebars are mounted below the seat.

The pedals drive a Sachs RS925 motor.

At the rear axle, the Quadvelo used a nine-speed freewheel cluster attached to a Samagaga differential . Two splined axle shafts are attached to the rear hubs. In the lower left of the picture you can see the longitudinal carbon-fiber leaf spring that supported the axle assembly. Also connected to the axle assembly are two dampers that are connected to an "L" shaped extension of the chassis. Braking is done by four hub brakes all around. 

The carbon-fiber leaf springs that support the front wheels is shown below.

The Quadvelo is 92" long with a wheelbase of 69". The vehicle width is 33.5" Vehicle weight is approx. 210lb and the cost of the basic model with doors is $13,2800.

Overall, I think the Quadvelo is well designed, but I think it could be improved. Looking at the assembled chassis without the body, I think that the wheelbase could be significantly shortened by at least 10" For reference, I am riding a delta trike with a wheelbase of 52"

Another concern is the cost. I don't know who would spend over $10,000 for what is basically an all-weather tricycle, limited to 15mph. If the Pedicar was updated with a derailleur transmission, hub brakes and a crank-mounted motor drive, the present day cost would still be less than $5000. So some of the Quadvelo's complexity should be eliminated to drop the cost.

Of course, the biggest problem with the Quadvelo is that four-wheel pedal assisted vehicles do not qualify as E-bikes in North America. The regulations state the vehicle can not have more than three wheels. 

Now a quad vehicle has 50% more roll-over resistance than a trike having the same track (lateral wheel spacing). So it is difficult to design a trike to meet my design requirements without having it be able to lean into corners. I won't discuss leaning trikes here, since I have written about them ad nauseum in other blog articles. So a quad layout, despite the complexity of another wheel, is a preferred layout for an all-weather, pedal-assisted commuter vehicle.

If E-bike speeds were all limited to 20mph, then I would recommend that four wheels would be allowable and require the width of both three and four wheelers to be 34" or less. Unfortunately, I feel that the 28mph speed limit for class 3 E-bikes is unacceptable with a vehicle as large as the Quadvelo.

Think of the potential damage a 400+lb vehicle could cause if it hit something or someone at 28mph.

Class 1 & 2 E-bikes can go up to 20mph and my experience is that when my leaning trike, that is plenty fast.

Hephaestus 

 

The E-Car-Go, a Compact, Leaning Cargo Trike

 

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

A Full-body Exercise Recumbent: The Omnidyne 3P

 

My readers will recall that I previous did a post on my experience adding arm power to my Avatar recumbent.

http://lefthandedcyclist.blogspot.com/2012/03/arm-power-and-avatar.html

Now to recap, the Avatar approach used a bolt-on rocking-handlebar and a freewheel added to the left side of the crank axle. Pulling on the handlebars pulled on a chain passing under the crank freewheel moving the pedals forward. A spring attached to the other end of the chain moved the handlebars backward when the pulling force was removed. The linkage connecting the handlebars to the steering was designed to decouple the rocking from the steering.

This arm-power-mechanism worked fine for riding on the flats but was not efficient for climbing hills. Since the handlebars moved at about half the speed of the pedals, the force from pulling on the handle bars was applied every other pedal stroke. On hills this resulted in there being more torque than needed for half the cycle and less for the other half.

The solution was to be able to push the handlebars as well as pulling them. The arms would contribute torque on each  pedal stroke.

 I would need two freewheels to accomplish this and couldn't fit them both on the left side of a single crankset. This meant I would have to add a second bottom bracket with three chainrings on the right side and two freewheels on the left. On the right side, innermost chainring would be connected to a single chainring driven by the pedal crankset.  This would be mounted in front of the second bottom bracket. Back to the right side, the middle and outer chainrings would drive the rear cassette in the conventional manner. 

The presence of a second bottom bracket required that I build a new frame to support it. And I realized that if I mounted the pedals directly over the 16" front wheel, I could shorten the wheelbase of the new bike by 12" when compared to the Avatar. The steering decoupled handlebars would be transferred from the Avatar but modified to facilitate the dual drive.

The freewheels used were the same size as used on the Avatar. Since the force produced by the handlebars with the Avatar was well matched to the pedaling, the goal was to keep things the same for the Omnidyne. The rocking handle bar has two beams attached to it, one on either side of the freewheel  pair. Pulling back engages the outer freewheel while the other freewheel ratchets. Pushing forward engages the inner freewheel while the outer freewheel ratchets. The beams started as the same length used on the Avatar, but since a greater force could be produced pushing compared to pulling, the pushing beam was lengthened. The distal end of each chain is attached to a spring to keep them taught.

As of late I haven't painted the parts and the Omnidyne has not been ridden outside. I like the new motion so much I have been using it as an exercise bike for the last year. I am confident that the push, pull, pedal motion, (3P), will drastically improve the bike's hill climbing.

Hephaestus