h a l f b a k e r yOn the one hand, true. On the other hand, bollocks.
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Skates such as roller blades that are powered by the users redistribution of weight.
As an integral part of the skate is a mechanical mechanism that transfers a downward force (user stepping on the skate) into forward drive - this could be done via the use of a crank arrangement with chains/gears/pulleys
etc. Platform of skate returns to top after push cycle.
Benifit - bicycle type speeds could be reached on skates!
Converting downward force into forward motion
http://www.howstuff...cycle.htm/printable
I completely fail to see how this is not reinventing the bicycle. (But if the standing up part is really important to you, there is always that pedal board toy that I cannot seem to find a link for.) [DrCurry, Jun 07 2002, last modified Oct 04 2004]
powerskip
http://www.powerskip.de/mainpage.html
watch fantastic videos (russian army by the way made motor driven jumping boots, but dicontinued them because of severe back aches and leg damage to testing staff. [pashute, Oct 04 2004]
Old invention
http://www.american...ma/invent/skate.htm
Seems someone attempted something similar once [pashute, Jul 13 2006]
[link]
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How is the downward force converted into forward motion? |
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1st stride, your weight shifts to one side, which consequently slides forward, leaving the other stationary. Could be pretty tricky to master. I picture this looking something like moonwalking, only forwards. |
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[scltd], some sort of racheting clockwork system, I imagine. |
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See thats whats missing. The idea in this istance could be applied to any mode of transport. The important and interesting thing here is the actuall mechanism. I think a little bit more explanation needs to go forward in order to show Osborns true genious. |
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I can picture the mechanism okay. (I'm picturing the heel part of the skate as being the bit that lifts and depresses.) |
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But this method presumes that the amount of force necessary to move a skated foot (and its carried weight) forward would be equal or less than the force generated by pushing down with the foot. Is this the case? It seems to me it would not be, but I don't know what I'm talking about. |
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OK, imagine a sissor type stucture - wheels at the bottom, foot platform at the top and pivot point in the middle. The arangement is 'normally' held extended by means of a spring - you put your weight on it the 'sissors' open and the spring compresses.
On of the 'arms' of this 'sissor' arrangement is like a crank which pulls a chain - turning bicycle style cog wheel and driving skate.
Chains and cogs would be best to use here as they are more efficient at transfering energy than gears - simple bike parts could be used along with pneumatic tyres for low rolling resistance. |
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Ah, so it's like a crank and follower type thing. See, a little explanatio goes a long way. Croissant. Well done Osborn. Hiphip Huzzah. |
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waugsqueke, amongst other things it would depend on the efficiency of your mechanism - But a given amount of force being 'pushed' down would take you forward by a given amount - think of a bicycle!
How far you go per downward stroke would depend on gearing, wind resistance, rolling resistance, rider weight and size and prehaps technique. |
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Hm. Still dubious about the force bit. Not quite the same deal as a bike, as a bike's pedals are connected to the same gear business, whereas your feet are ideally not connected to each other. |
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Perhaps an alternate method would be to create skates that have the same sort of pull-back-and-let-go wind-up mechanism that kids' toy cars have. To move forward, roll your foot backward and hold on. |
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Um, how do you decelerate from your bicycle speed? You're going to need to stop quickly in case of an emergency. |
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Perhaps a simpler form would be to just have skates with one-direction ratcheting wheels. |
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Dag - you could add on brakes. |
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waugsqueke - you are right - having both feet connected to the same power means is an advantage (like on a bike) I am just suggesting this as a way of improving skates. The human body can deliver 250Watts of power continously - this just is a better way of ultilising this power compared to existing skates - where the drive means is inefficient. |
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Rayfordsteele - I have seen skates with one directional ratcheting wheels - this is good especially for climbing inclines (or even steps for that matter).
However, with this kind of skate you will still have a limited top speed. |
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You know those flashlights that are brighter when you pump the trigger (rev it up)? What if the skates were bolted together and the trigger was in the heel. This way it would kinda be like running. Did any of that make sense? |
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Barnzenen - good idea - though if both skates are mounted together balance would be harder. But you could take this mechanism and put it on a skateboard. |
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You'll never reach bicycle speeds without a great deal of gearing - a 10-speed rollerskate? Why not just use one of the motorized ones available now? |
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"this just is a better way of ultilising this power compared to existing skates - where the drive means is inefficient"
I'm not buying it. Your idea relies on gearing and gravity to power the skate. Conventional skates allow me to use muscle and gravity to power the skate. I can't push down with any more force than I weigh (without pushing off something else). On the other hand, I *can* push forward with more force than I weigh. |
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phoenix: just because you're pushing down with maximum force now doesn't mean that you are using the downwards force from gravity as effectively as you could be. |
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phoenix, please do not bring hands into this - I am confused already <po wanders off , looking slightly strange in the direction of the home for the bewildered> |
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[yamahito] Don't tell me, tell [Osborn]. |
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[po] Hands placed POlitely behind by back, standing 'at ease'. |
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You'll never reach bicycle speeds anyway. Wheel / bearing size ratio is too small. Too much rolling resistance. Take a little rubber superball and a big kickball and roll them down a hill; the kickball will win every time. |
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From a technical standpoint I agree with phoenix. This won't be an improvement in force utilization, because of crank system losses and other factors. You can push backwards harder than gravity will pull downwards. But it sounds like fun, anyway, if a nightmare to learn how to control. |
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If we really want bicycle speeds, we're going to have to
make "penny farthing" roller skates, where the wheel(s)
on each skate is (are) several feet in diameter. The
wheels would have to be either on the outside or on both
sides of the skate, and the skate's boot will have to
extend quite high up the leg to provide support, but you
will look really cool on those... |
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You are all right - rolling resistance is important - I have already suggested using larger (prehaps pneumatic) wheels - not the 'didy' skates wheels currently employed by many street cruising devices. |
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Using say 4-5 inch wheels rolling resistance would be pretty neg. - actually air resistance would contribute more - about 80% of the resistance encountered (for speeds over 12mph)- similar to a bike. |
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In fact if this product was developed properly it could out perform a standard bicycle. |
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Increasing the wheel size would create problems with balance: it would be like trying to walk in very high platform shoes. |
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Another issue is in tailoring this to the way the leg works. Bicycles let you push down your leg a considerable distance, from bent right up to straightened out. This is close to the action in running, for which human legs are relatively well designed. Doing shorter and quicker motions would be less efficient, and if you sought to increase the distance of vertical travel on your skate, so you had to lift the (possibly heavy) boot a foot in the air for each stroke, this would probably cause problems for balance. |
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To solve the balance issue, the centre of mass could be way below the axles. |
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At bicycle speeds (20-25mph) uneven surfaces would pose a serious danger to small wheeled devices. 16" is the smallest serious bike wheel size, and even these would usually have suspension.
Braking from 25mph is another problem. It would be easy to add a braking mechanism to halt the skates, but the rider would continue at 25mph, pivoting about the axis of the front wheel, or if the users survival is important, continuing until intercepted by a soft biped. |
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I have multiple friends who can out pace cyclists when they are on roller blades. |
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Skates are already self-powered. If you've got a concrete design for better efficiency, go for it, but without that it's just hand-waving. |
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My wife bought me a scooter coming back from Sydney, that works by pressing on alternate parts of the footstand. Looks real fancy and she knows I love gadgets. They told her it was one of the first of its kind in the world, and they were just checking peoples responses, before improving the design. |
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Anyways, my girls love to play with it, but its completely not practical: wont help when going down, and doesnt work at all going up, in any case its too heavy. |
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I hate saying bad things about ideas. Instead, I would rather help you think of a good solution for problems which arise with your idea, so here are my thoughts. The problem, I think, is the ratio and size of the moment. The solution is to have the thrust rod all the way up to your arms: so your whole body: Foot, hands and stomach muscles, help with the downward thrust. |
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And bookworm: take a look at [link: powerskates] which can show you that there is a lot to be done over nature's feet using our own body's power downward thrust. (Actually a bicycle and regular skates themselves show this, so do not poo poo away this idea). A Jewish sage once said: "Do not disregard ANY idea, or look down at any person, for there is no person without their correct place and no idea without it's correct time." |
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3 years later found a [link] from 30 years ago... |
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