How does this work?

[Solvo]

Thanks, I thought there would have to be a vent....those seals must be pretty special to cope with running repeatedly over it, must be very resilient even running over a smooth apperture,

Why would the vent be in a part of the cylinder that the seals pass over?
The output vent to the storage is most likely in the end, I dare say the intake is likely piped to that same end, or possibly even just a valve in the piston itself. It doesn't have to be in the sidewall of the cylinder, there are other options!

[air-tech]

Why would the vent be in a part of the cylinder that the seals pass over?
The output vent to the storage is most likely in the end, I dare say the intake is likely piped to that same end, or possibly even just a valve in the piston itself. It doesn't have to be in the sidewall of the cylinder, there are other options!

This. While not familiar with multipump guns, I know that with multipump lots of other stuff there is often a simple valve in the piston itself.

[robs5230]

This. While not familiar with multipump guns, I know that with multipump lots of other stuff there is often a simple valve in the piston itself.

The valve in the piston body is a valve that blows off when pumping gets to a certain pressure. Its for power regulation only

[bezzer]

Why would the vent be in a part of the cylinder that the seals pass over?
The output vent to the storage is most likely in the end, I dare say the intake is likely piped to that same end, or possibly even just a valve in the piston itself. It doesn't have to be in the sidewall of the cylinder, there are other options!

Yes, but pumpers are usually simple animals, the cylinder vent/air inlet hole is a very easy and simple system that works. My Blue Streak had a vent hole and was on its original pump seal after 40 years, still pumped fine with no leaks.

[T 20]

Why would the vent be in a part of the cylinder that the seals pass over?
The output vent to the storage is most likely in the end, I dare say the intake is likely piped to that same end, or possibly even just a valve in the piston itself. It doesn't have to be in the sidewall of the cylinder, there are other options!

There's either a vent hole at the end of the pump stroke or the piston head moves forward far enough so that it breaks cover in the cocking lever slot to take in air.

The vent hole in the cylinder is small enough and finished well enough that it causes no wear on the seal.

I've never seen a multi pump with a one way valve in the piston head to allow air in, it would just be an over complication that's not needed.



All the best Mick

[trajectory]

Thanks for all the replies, that's clearer now.

[TonyL]

On opening the pump arm, there's a point at which the vacuum in front of the pump seal will vent, either by the seal clearing a slot or a drilled hole, allowing the next lot of air forward of the seal to be compressed on closing

There's either a vent hole at the end of the pump stroke or the piston head moves forward far enough so that it breaks cover in the cocking lever slot to take in air.

The vent hole in the cylinder is small enough and finished well enough that it causes no wear on the seal.

I've never seen a multi pump with a one way valve in the piston head to allow air in, it would just be an over complication that's not needed.



All the best Mick

Yep, absolutely.

And, although unlikely to ever cause seal wear issues, the hole or slot could be de-burred if considered necessary.

[Shed tuner]

There's either a vent hole at the end of the pump stroke or the piston head moves forward far enough so that it breaks cover in the cocking lever slot to take in air.

The vent hole in the cylinder is small enough and finished well enough that it causes no wear on the seal.

I've never seen a multi pump with a one way valve in the piston head to allow air in, it would just be an over complication that's not needed.



All the best Mick

yup. The only times I have seen valves in piston heads is to dump air when over pressurised, to prevent them going OTT... nothing to do with air intake... quite the opposite in fact !