Spokes on a wheel?

[Tom Dunlap]

Thunderstorms here this morning so I decided to rewatch The Guns of Navarone. In this scene with Anthony Quinn I see a wheel crank with spokes that have mystified me for years.

Maybe one of the mechanical engineer coves here could solve the mystery for me.

A simpler design would be with straight spokes. Having them in the S shape uses more material it seems but there has to be a purpose. There are lots of examples of this type of spoke on a wheel crank or single arm crank.

I've wondered if this configuration puts more torque on the axle than a straight spoke. I dunno???

 

[TreeLogic]

i'm no engineer..well maybe a wannabe. anyway, seems stronger with the curves to me, tom.
1) like you said, more material
2) covers more area between spokes
3) doesn't the bending pretension the iron?

 

[surveyor]

It may have something to do with the crank being cast iron and allowing for the relief of thermal stress after being cast, or not. Perhaps is is merely an aesthetic design element.

 

[boreality]

I'd guess mostly for looks or it could make for better ergonomics during a storm when more than one crew has to pull on the helm. Or it could help with tying the wheel off with rope to prevent the knot slipping into the hub.

 

[Tom Dunlap]

Here's a reply from another forum that I posted the same question:


Metallurgical Cove here - The answer has to do with solidification and shrinkage stresses associated with taking a metal casting from the liquid metal state to room temperature. The curved configuration, allows the spokes to shrink with the rest of the casting without pulling apart.
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There is still more to answer about the s shape though. I see the same s shape on single handled cranks too. I'm going to try and find examples later.

After pasting the above answer in I checked the third site that I asked. This answer accounts for the right or left handedness of cranks:


I have spent a few years in merchant marine {when I was younger and better looking) including some in the engine room lot.

Curved spokes simply indicate which way the wheel has to be turned to open or close, especially useful in the dark when you can tell by feeling the spoke shape.

 

[Adkpk]

Great piece of trivia there Tom. Good one.

 

[marlinspiker]

love that movie.