Tuesday, 4 May 2021

The Tea Tray...

Some years ago, Scrobs had an idea...

Skate boards were in their infancy, and while I'd grown up with 'go-carts', (not the powered ones, just the set of pram wheels nailed onto a wooden frame), and had enjoyed hours of immense fun racing down the hills near our home, I'd seen an article about a 'Gyrobus' in a magazine, which sparked something in the Meccano-riddled brain which inhabits this ol' head!

The concept is explained here



I wondered if the principle could be applied to a much smaller piece of equipment, and started to put together some ideas on paper, with absolutely no knowledge of what I was doing at all! Like many young boys, I'd had several of those toys which had a tiny flywheel driving the wheels, so you pushed the car along the floor, let go, and it would travel onwards for a few yards. I loved these models, and cherished their simplicity, as wind-up toys invariably broke when the spring got too tired!

The flywheel concept developed into these sketches...





Again, knowing absolutely nothing about the technology, as this was occurring way before the internet, I still felt that 'The Tea Tray' would work! I reckoned that the flywheel could be made from concrete set in a mould, with small indentations to fill with lead for perfect balance, and the flywheel boss connected to the rear wheels via a belt (not a chain), to drive the thing. 

One would sit on the machine, rather like you would on a small snow-sleigh, and you would start the fly wheel going with a pedal and ratchet. The clutch was a simple release device, which disengaged the axle at the rear with a bicycle brake lever attached to the side. Braking was by virtue of disengaging the flywheel, and sticking one's legs out as one always did on the go cart! If one kept the wheel engaged, going downhill would keep the motion going for longer.

Steering was an issue which was resolved by having a 'v' shaped rocker on the front wheels, so that if one leaned to the right, it would turn the wheels which were built onto a simple rack and pinion system. It all seemed to work - but in this ol' head only!

The Gyrobus didn't last either...


3 comments:

Sackerson said...

Interesting line of enquiry. E.g. https://www.youtube.com/watch?v=oeY1i4qkDgQ

A K Haart said...

Maybe you could have tried using a small energetic dog in a treadmill system to start the flywheel spinning.

Scrobs. said...

Sackers, that was most interesting - thank you!

Regarding friction, a good friend told me the following, which gives more understanding to the concept of friction .

"The mention of frictional losses reminded me of a promotional device which my Father once brought home for me. He was in the engineering business and dealt with a company in Plymouth who specialised in fine tubes made to infinitesimal tolerances.

They produced a cylinder which spun on a shaft that was machined to such tight tolerances that the cylinder rotated on an air cushion. Once spun up using a piece of string (a la pull starter) it would spin for several minutes (like 5 or 10) unrestricted by mechanical friction but ultimately, presumably, slowed by air friction".

The Professor descibes the system as working in a vacuum, so this may alleviate whtever friction might occur? I don't really know, but there seems to be some correlation between frictional loss and the technology described!

MY 'tea tray' relied on constant ratchet-'pump' by foot pedal to keep the flywheel going, so no vacuum was intended, but I imagined that like one of those toys, if you kept pushing it along more and more, the rate of speed would increase - well it did on one model car I had!