Aerolight Posted October 1, 2020 Posted October 1, 2020 Over the last few months I've been working on something new with pneumatics (still a few weeks away though), and while dissecting cylinders I came across the stroke quirk. The small cylinders don't have a stroke of 2 studs but slightly less, this is why the good pneumatic engines use connecting rods - the extra pin connections add just enough slack to allow a 1 stud crank to spin relatively freely. This has been known since they first came out. A similar problem occurred with the original small pump and later Lego released a new style pump that did not have this problem (it did like to crack through) as is was longer. You may have noticed these later pumps look very similar to a power cylinder just missing the top port and adding a one way valve. Well when measuring the inner depth of these pumps, we find they are longer than the stroke plus piston. Infract the inner wall is the exact length to allow a power piston with its top seal(pumps don't have this witch is why they do not take up the entire length) to travel 16mm (2 studs). From this we can say that lego once planed to make a new small cylinder with a slightly changed pump frame (only structure change is adding a to air port). The only new element would be a slightly longer piston rod/connector, but at some point they decided against it. However if someone wished two they could make a new piston rod and make a new improved cylinder out of a pump, although removing the one way valve is a bit tricky you can always count on Mr drill. The added internal length of the pumps also allow to make something a bit more interesting if u are so inclined.... Quote
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