the first ever human powered car
for people, for the planet
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by Sebastian Cruft, the Inventor of the HUMO™
In the summer of 1995, I had arranged to visit the buyers at one of our significant customers. This involved a journey of 200 miles (300 km) in each direction. As I was still able to drive a car, I set off at about 6 a.m. and arrived in good time for the first meeting, showed samples of new products, took notes of the buyers' comments, and had a simple lunch. Then I had two more meetings, drove to a motorway cafe for tea, and set off for home. I arrived home quite late.
My wife suggested that I unwind with a magazine article which had interested her. Green issues were quite rarely discussed in the media at the time. The article described a new organisation which was campaigning to replace motorcar use with bicycles.
As I read it, I thought of my day. I had driven 400 miles in 8 hours, at an average speed of 50 mph, with a top speed of probably 80 mph on motorways, dawdling at 40-50 mph on country roads. I had been able to hold three meetings in business clothing, had carried the normal business 'stuff' of briefcase, laptop and sample-bags, and had done it all in one day. MS was already preventing me from riding a bike, but even 20 years ago, could I have done this on a bike? So I started doing some mental calculations, and concluded that to do on a bike what I had just done in a car would take about a week.
I suppose this was the Eureka Moment. I started thinking about possible alternatives to bikes and researching them. Recumbent bikes were just starting to appear, but although they were probably quite fun on a racetrack they didn't seem safe or practical on the road - too low and unstable.
Fortunately, the company I worked for was just starting a project for a 'one-off' slicing machine. Mike Moore, the engineer, kept talking about using sprag clutches in order to move the foam slab repeatedly in one direction. Nowadays you can look them up on Wikipedia, but that resource was not one I knew. It took me a long time to understand what he was saying but when I had seen the new machine working - it cut 80,000 sheets in two months, and saved knee injuries for 2 people. I suddenly realised that it would be ideal for turning the forward push of a human leg into rotary movement - and that moreover one could lengthen the crank arm to multiply the torque - and that moreover the rider could sit upright within four wheels like the driver of a car, with good all-round visibility and stability, and that in theory these vehicles could ride on rails with a simple railway-flange added to the wheels, and that they should be able to take brief-cases and laptops and shopping and overnight bags, and be boosted by electric motors etc. etc. - see British Patent 2403698.
However the infuriating disadvantages of disability now struck me. I could still walk a bit with a stick, but I couldn't squat or kneel, and my left hand was becoming useless. In earlier years I had been reasonably practical, but now I would have to pay for any prototypes and persuade engineers that they were not wasting their time.
Anyway, I persuaded Mike to make a proto-prototype - a 'rope-brake' dynamometer which compared the output of human riders on a conventional bicycle lifting a 25kg weight by rotation of the rear wheel with that of the same riders using the new sprag-clutch drive. My colleague, Paul, passed me a copy of the 'Rino'- now 'Ondrive' engineering catalogue. The cranks for each were normal 15 cm bike cranks. I was very much helped in this by an engineer friend John West, who drew up a scheme for the dynamometer and operated it (along with Mike).
The upshot was a clearly visible difference -
with the bicycle, the weight went up, then down, then up, then down.
with the sprag-clutch the weight went up, then up, then up - always up, until the rafters in Mike's workshop were reached.
I tried to get the measurements - a complicated business involving 'radians'. I did my best despite being unable to squat down. It looked to me as if the 'bike' method gave a power of 100 watts, and the sprag-clutch method gave 900 - 1000 watts - approx. 1 h.p.
Then the engineers said you should try it on a wheeled vehicle. Mike was too busy. He very tactfully pointed that, as with the cutting machine, most of his customers were people with ongoing businesses dependent on what he made for their daily income. He very kindly reduced his invoice and absorbed the VAT.
In despair I bought a go-kart kit from Gemini Karts, and started to look for someone to make it into a wheeled prototype. Mike suggested a friend, Des Chudley, who made it into the vehicle which you see being tested on the road and airfield in 2005.
Further delays followed due to my disability and the demands of the day job. Then in 2013 I resolved to try again. Seeing that the main problem with the kart prototype was the 80kg weight, my plan was to have a much lighter prototype made all in wood - like the 'stringbag' Fokkers and Sopwiths of the first World War - and covered in fabric. The REV21 series of drawings was prepared following my instructions by Ian Kennard of SK Drawing Services. Unfortunately, in the end, the vehicle was made with a 40mm steel frame and weighed even more than the first one - 115kg! John Hartnell built it to a very high standard. In the video, you can see it running efficiently but slowly in a barn, driven by Ian Kennard.
Thinking hard about the need to reduce weight, I tried researching an aluminium alternative. As I did so, I realised that if it was as light as I planned it would be an easy thing to steal, so I decided to adopt a folding configuration which would mean that it could be stored, like a bicycle, in the home or the office. This prototype will be covered by 'hi-vis' fabric, like the safety jackets worn by road-maintenance staff, to provide an aerodynamic, weatherproof bodywork.
This is the prototype for which your support is needed.
Ian is ready to design the wheels, gears etc. and John will attach them. Because the frame will be aluminium - and 21kg + running gear, it will be possible to use ratchets rather than sprag-clutches. (see our Frequently Asked Questions).
Any questions? Please get in touch -
Website designed and built by Chertstone
Original music © Benedict Cruft