SoftBank Team Japan

SoftBank Team Japan foiling at high speed. Photograph Matt Knighton

How those pedalling Kiwis aren’t the only show in town for innovative pedal power hydraulics.

55mph composite America’s Cup catamarans take hi-tech sailing to the limit

The foiling catamarans developed for the America’s Cup are serious engineering in Sarums’ eyes. Lightweight composite structures skim above the water at up to 55mph on foils and are driven by a massive solid aerofoil “wing” sail larger than a jumbo jet wing. The crowning touch is that rather than conventional rope “sheets”, this is a hydraulic sailing boat. And manual hydraulics as well. Three or four incredible human hulks turn hydraulic rotary piston pumps using ferocious “grinder” handles. These in turn charge up nitrogen gas accumulators which are then used to power assorted hydraulic cylinders controlled by the helmsman using up to 40 hydraulic control valves. Whether it is controlling a foil or trimming that massive wing sail, hand (or human) powered hydraulics has been the only power source allowed by the rules. 

Or at least hand-powered hydraulics has been the way to power the assorted hydraulic cylinders and actuators until now. Despite other teams disregarding the idea as “one we thought of but dismissed”, Emirates Team New Zealand (ETNZ) seems to have sorted pedal power. As these hot rod catamarans hurtle along, four hulks will run over from one hull to the other and jump on to four “bikes” then pedal furiously. From the media, our impression is that the Kiwis could just be on to something that is making a real difference. Might pedal-powered hydraulics be the winner that defeats the USA? 

Sarum Hydraulics are the experts in manual hydraulics. We know well that however optimistic a customer might be, arms will only generate a finite amount of energy. In a world that now loves power-assisted everything, arms will never produce as much power as you would think they should when you look at the hard facts. Humans evolved as runners, using their arms more for manipulative tasks — and a quick search on the internet will tell you that human legs are four times as strong as our arms, however that is quantified.

Pedal Power hydraulics on Emirates Team New Zealand
Photograph New York Times

 

Hand or pedal?

Look instead at bicycles and you soon understand the massive, explosive power harboured in our legs. The average fit person can generate 100 to 200 watts for 30 minutes without great exertion using their legs to pedal their bike. At his limit, Chris Hoy might be generating 400 watts consistently during a 60-minute period or peak at 1500 watts during a sprint. Putting this into context, a decent DeWalt or Makita battery hand drill (which seems to us to be pretty cutting edge compact portable power) will kick out around 350 watts. So, you can get a feel for what energy is available to run the AC hydraulic catamarans and what uplift Emirates Team New Zealand might expect from leg power. We have not studied how long the lads are pedalling for, but four people pedalling intensely for 30 seconds might well be kicking out upwards of 4kW or over five horsepower in old money. 

Pedal power was used in a massive range of machines before electric motors — think of spinning wheels, lathes, threshers and no end of other machinery. For many, that was the only available power for the cottage industry and the big plus was that using feet to generate power left hands to do the production job. Other than water pumps, these were purely mechanical devices rather than hydraulic drives.

Why not pedal power?

What other pedal powered hydraulics can we see in the modern world, away from the America’s Cup foiling machines? Well, entrenched are pedal powered hydraulic chairs for hairdressers and pedal lift hospital beds and day surgery trolleys. Here, depressing the pedal will pump up and lifting the foot pedal will allow the single acting cylinder to lower. You might incorporate a pressure-compensated flow control valve so that the unit does not come crashing down with a heavy customer or patient. Sarum has made a slick pedal-operated pump for years for a large UK medical manufacturer.

And that is pretty well the limit of enquiries to Sarum over 30 years for pedal-powered hydraulics. Why? We don’t really know. Maybe if “stuff” happens up at hand level, people don’t like a foot pump on the ground. Where there isn’t electricity, there seems to be quite an interest in pedal-powered washing machines and water pumps for domestic use and all manner of pedal machinery for third world agriculture. Those cocoa beans used to make expensive, artisan chocolate may have been ground on a pedal-powered grinder. Making your pedal-powered machine into a hydraulic machine adds complexity but can add a whole new dimension (and power) for doing jobs. High-pressure pumps, massive forces and storing hydraulic energy to give very high loads during part of a cycle are potential big wins.

Our four pedal hydraulic favourites.

Given the power of leg muscles to run serious hydraulic machinery, what about our four favourites?

– Pedal-powered desalination units might just cut out the need for exotic motor driven piston pumps on low tech RO units for the third world

– Foot-powered hydraulic waste compactors for domestic use. Could compacting waste at source dramatically cut the volume of landfill and the number of truckloads for recycling? Sprawling landfill sites are a challenge all around the world

– Foot hydraulic hard disk crushers. We don’t know how many hundred million hard disc drives there are kicking around in the world, but we would be happier to destroy our own locally. That is the sure way to be certain that the data has been destroyed.  

– Pedal-powered water pumps for the third world are always going to be a good product. Making them cheap but rugged is the engineering challenge

Going back to the America’s Cup in sunny Bermuda, the Kiwis have shown some true ingenuity. Despite all the ergonomic worries associated with fitting people onto a “bike” on a catamaran, clever design and ruthless training of the crew has made it work. Let’s wish them success now that BAR Land Rover are out. We love innovators who make a great idea work.

Contact the experts to discuss your hand or foot hydraulics application. Telephone Sarum Hydraulics on 0044 1722 328388 or e-mail us on pumpsales@sarum-hydraulics.co.uk

Useful Links:

There is remarkably little on the web on America’s Cup hydraulics, probably because of “secrets.” This article is good. http://www.sailingworld.com/tech-behind-americas-cup

Keep up to date on https://www.americascup.com/en/bermuda.html Great entertainment even if you are not a sailor.