FOOT PUMP for PCP's?

[Gerry52]

After years into this activity I'm always surprised that I've never seen a HP foot pump. I'd think a foot pump would be far easier to operate & generate the force needed for pumping up a PCP. Thoughts anyone?
EDIT: I've definitely lost upper body strength & KNOW my legs are much stronger. I just figured with leg strength plus full body weight a "foot" operated pump might be easier (not that I need a pump, either hand or foot). Just curious.

 

[nervoustrig]

A foot (leg?) pump would seem attractive if the established crop of hand pumps actually relied on arm strength. Fortunately they don’t. Pumping technique relies on locking the arms and then driving down with one’s body weight.

 

[AlanMcD]

The problem with a foot pump for PCPs is that these are multi stage pumps - there is pumping that occurs in both directions in our handpumps (meaning on the upstroke as well as the downstroke on a hand pump). That means that a foot pump would not be able to return to the "up" position after we step on it, as we see on foot operated bicycle pumps - in those a spring does the small amount of work needed to raise the foot peg.

I suppose one could be made, but you would have to make two different stepping motions on it, and one would take much more weight to achieve compression than the other.

 

[Nomadic Pirate 66]

Rowing machine, rowing machine, rowing machine.....with 2 big pumps one on each side.



Please someone make it, I would be the first to buy one !

 

[jarmstrong]

a stepping exercise / foot pump is do-able, BUT higher material cost and takes up more room , the stair stepper would need a handle bar for balance.
stepping is easier as It does not require upper body strength,,, is it market feasible? that is the Question
yes, your arms and shoulder muscles work just to hold your weight in balance over the pump handle,,, if it was easy, we/I would not be complaining about it

 

[Scotay42]

Rowing machine, rowing machine, rowing machine.....with 2 big pumps one on each side.



Please someone make it, I would be the first to buy one !

Shoot i got an old total gym, now just need 2 hand pumps and a couple hinged brackets.

 

[WorriedMan]

Shoot i got an old total gym, now just need 2 hand pumps and a couple hinged brackets.

Imagine a company coming out with a kit to modify those unused workout machines to PCP pumps.

 

[BackStop]

The problem with a foot pump for PCPs is that these are multi stage pumps - there is pumping that occurs in both directions in our handpumps (meaning on the upstroke as well as the downstroke on a hand pump). That means that a foot pump would not be able to return to the "up" position after we step on it, as we see on foot operated bicycle pumps - in those a spring does the small amount of work needed to raise the foot peg.

I suppose one could be made, but you would have to make two different stepping motions on it, and one would take much more weight to achieve compression than the other.

I have seen this posited a couple of times over the years and it always makes me wince.

Hand pumps AND compressors, regardless of how many "stages" are involved, have a compression stroke and an intake stroke.

I have NEVER had nor seen a hand pump that makes compression on both the up and down strokes as you seem to be claiming.

However, I could be wrong. If I am, prove it. PLEASE! (smile)

I would love it. (grin)

Thanks

All my best!

Kerry

 

[AlanMcD]

I have seen this posited a couple of times over the years and it always makes me wince.

Hand pumps AND compressors, regardless of how many "stages" are involved, have a compression stroke and an intake stroke.

I have NEVER had nor seen a hand pump that makes compression on both the up and down strokes as you seem to be claiming.

However, I could be wrong. If I am, prove it. PLEASE! (smile)

I would love it. (grin)

Thanks

All my best!

Kerry

I'd be happy to do so . . .

I put a detailed explanation of a how a three stage hand pump works up back on the old Yellow, but sadly it is gone. So I had to dig out my old illustrations. Here is a short explanation of how it works - I figured it all out as I had to trouble shot my Hill Mk2 years ago and made some crude (not to scale) illustrations to show what is happening in the pump as it works.

Remember that these are three stage pumps, so four things have to happen - an intake, and three separate stages of compression - from just two actions of the pump (upstroke and downstroke). Logic says that two should happen on each stroke . . . and that is made possible because these pumps consist of nested tubes for the different stages.

Bottom line, the upstroke delivers the intake and the 2nd stage compression, and the downstroke delivers the first and third stage of compression. The downstroke is much more difficult (on purpose) as it is performing two stages of compression, including the harder third stage. Also, it is the nested nature of the cylinders that result in the long cool down periods required for these pumps as it is hard to get the heat out from way inside them.

I never took apart a four stage handpump, so I don't know how those work in as much detail. While this is for a Hill pump, I'm pretty sure most three stage pumps have the same general construction. Here are the illustrations - the first one shows the layout of the illustration, while the 2nd and 3rd show what happens on the strokes:

 

[BackStop]

I'd be happy to do so . . .

I put a detailed explanation of a how a three stage hand pump works up back on the old Yellow, but sadly it is gone. So I had to dig out my old illustrations. Here is a short explanation of how it works - I figured it all out as I had to trouble shot my Hill Mk2 years ago and made some crude (not to scale) illustrations to show what is happening in the pump as it works.

Remember that these are three stage pumps, so four things have to happen - an intake, and three separate stages of compression - from just two actions of the pump (upstroke and downstroke). Logic says that two should happen on each stroke . . . and that is made possible because these pumps consist of nested tubes for the different stages.

Bottom line, the upstroke delivers the intake and the 2nd stage compression, and the downstroke delivers the first and third stage of compression. The downstroke is much more difficult (on purpose) as it is performing two stages of compression, including the harder third stage. Also, it is the nested nature of the cylinders that result in the long cool down periods required for these pumps as it is hard to get the heat out from way inside them.

I never took apart a four stage handpump, so I don't know how those work in as much detail. While this is for a Hill pump, I'm pretty sure most three stage pumps have the same general construction. Here are the illustrations - the first one shows the layout of the illustration, while the 2nd and 3rd show what happens on the strokes:

View attachment 438038

View attachment 438039

View attachment 438040

There is NO compression on the UP stroke. All of the compression happens on the down stroke. The up stroke is simply for intake of air.

This is true for hand pumps and compressors. If there was compression on the up stroke with a hand pump, it would be damned hard to lift the handle. The same is true for compressors.

What you posted did NOT prove compression on both strokes by any means. Anyone who has used a hand pump for any length of time can attest to that.

All my best!

Kerry

 

[nervoustrig]

Kerry, you may want to look again.

 

[AlanMcD]

There is NO compression on the UP stroke. All of the compression happens on the down stroke. The up stroke is simply for intake of air.

This is true for hand pumps and compressors. If there was compression on the up stroke with a hand pump, it would be damned hard to lift the handle. The same is true for compressors.

What you posted did NOT prove compression on both strokes by any means. Anyone who has used a hand pump for any length of time can attest to that.

All my best!

Kerry

Sadly, I figured that would be your position. But what I posted is how it works.

Feel free to take one apart and show what you determine to be how the air moves through the pump.

I don't know how to "prove" it to you, and I don't really care to . . . Peace.

 

[Camaro454]

This could help.

 

[Sawney Bean]

This could help.

That really seems like a goofy pump design to me. Assuming their animation is correct, the second stage does nothing and ultimately it just turns into a one stage pump at the end of the stroke anyway. It seems to me that you could just ditch the added weight and complexity and just make it a one stage pump from the start.

 

[RIshooter]

The problem with a foot pump for PCPs is that these are multi stage pumps - there is pumping that occurs in both directions in our handpumps (meaning on the upstroke as well as the downstroke on a hand pump). That means that a foot pump would not be able to return to the "up" position after we step on it, as we see on foot operated bicycle pumps - in those a spring does the small amount of work needed to raise the foot peg.

I suppose one could be made, but you would have to make two different stepping motions on it, and one would take much more weight to achieve compression than the other.

I can see it now, the first pcp stair master.

 

[F6Hawk]

I have seen this posited a couple of times over the years and it always makes me wince.

Hand pumps AND compressors, regardless of how many "stages" are involved, have a compression stroke and an intake stroke.

I have NEVER had nor seen a hand pump that makes compression on both the up and down strokes as you seem to be claiming.

However, I could be wrong. If I am, prove it. PLEASE! (smile)

I would love it. (grin)

Thanks

All my best!

Kerry

Every stroke (up AND down) creates pressure in a multi-stage pump, whether hand- or motor-driven.