Stirlingengineforum.com

I am a newcomer to this site, a longtime modeler and I have made several sucessful stirling engines, but my latest is not working! Something is very wrong. It is a version of the Hayward rider water pump and I had to guestimate the essential parameters like the bore/stroke ratio, the swept volumes of each piston, and the size of the transfer port and other less vital dimensions. I have to contact people who have real engineering knowledge of these things. The best thing would be an engineering drawing showing and stating the vital statistics.
Is there anyone 'out there' who can and will help?
I should say that I am a lifelong precision toolmaker/designer by trade so to speak(now retired)
Auto cad conversant.
Cheers. Brian.

Hi Brian, The ratio of the two strokes is 1.5 : 1, displacer to power, one of the main problems you may have is friction caused by tight or miss alined bearings, or an air leak, possibly in the displacer. For the initial run try without the pump hooked up, if you use the water from the pump for cooling you could attach a hose to a tap, and turn that on so theres just a trickle.
The power piston should just slide down the cylinder under its own weightwhen its unattached to the crankshaft, NO OIL on the piston. Ian S C

Brian replies to Ian sc
Thanks for the response. I will post a picture soon, but I will give descriptions now. The engineering is of high quality. The cylinders are cast iron lapped to mirror finish and parallel to a few microns. The pistons are made of amorphous graphite and are almost friction free. There is total freedom and high compressive resistance even when hot.
Your comment as to the stroke ratios I have seen mentioned, but all the pictures and videos on line show no evidence of this however carefully they are analyzed. This refers to the many Hayward rider pump pics which I am trying to copy.
I am grateful for your comments and would appreciate any sketch/picture to help explain the stroke ratio, which mystifies Me some. Are the swept volumes for each piston different?
I have realized already that my transfer port/regenerator is much too small in cross section, and I have not included the internal baffle shown inside the 'hot cup which provides the initial heat, which seems to direct the heated air up the wall of this cup, to the transfer port
I hope this will be sufficiently descriptive to follow, assuming that we are both discussing the Hayward stirling water pump.
Cheers Brian Knight.

I'm not too sure the exact type of motor your's is, is it a single cylinder concentric, (BETA), or a twin cylinder (GAMMA), displacer type, or a two piston ALPHA motor. The first two are actually the same, just a rearraingment of cylinders, these the volume is 1.5 : 1 either by adjusting the stroke or bore to suit. The ALPHA motor has a 1 : 1 ratio, and has two compression pistons. Ian S C

Hi,I think you should do one thing. The power piston in the cylinder just slide under its own weight of his seminary separate crankshaft, no oil on the piston. Just try it.

To Martinnman
You should read my earlier comments! The pistons are dry and free in the extreme. The engine is an alpha type with 2 equal pistons and 2 unequal displacers as the many video and stills available on the net will show they are of full working engines not models. I have seen a working model actually running, but they seem to be very rare or very well hidden!!
Cheers Brian Knight.

Brian, the figures I gave are for a displacer type motor, your ALPHA motor the ratio should be 1 : 1. The hot piston usually has whats called a Heylandt Crown, this keeps the heat away from the head of the piston. You have proberbly studied Andy Ross's motors.
I have one ALPHA motor with a Ross Yoke, it runs well even though it has no complicated balance system, or regenerator. Ian S C

I had a query regarding the rider water pump.. The gas that rider water pump use should have a low heat capacity, so that a given amount of transferred heat leads to a large increase in pressure.But oxygen is a highly pressurized air engine gas that has high heat capacity..So using this gas might be little risky.So which gas would be the best gas that has low heat capacity???

Light gasses work better than heavy gasses. Hydrogen works very well, but is difficult to contain. Helium is the only alternate gas I have used in a Stirling engine. I like it because it is cheap, and it gives about a 10% boost in engine performance.

This motor is an atmospheric type, so air is the only real option, helium, like (but not to the same effect) hydrogen will actually leak through the metal that the motor is built of, apart from any gap how ever small. its OK in a sealed, pressurised motor, but the problems start with the sealed bit!! The Phillips motors were pressurised air motors. Ian S C