Water pump dimensions

Hi, On my 2 in D & NY Traction Engine that i'm building I seem to have a problem with the water pump dimensions. That or I missing something. The water pump plunger is described as 3/8" bore with a stroke of 1/2" . When I look at the eccentric drawing, the offset from the centre of the drive shaft to the centre of the eccentric is shown as 1/2" To me that gives a stroke of 1". If that is right, then the plunger dimensions are wrong because at a 1" stroke the graphite packing on the plunger will come out of the bore. Of course, I could be completely wrong. So can any one help me please.

Cheers Garry

I think this drawing is the D&NY water pump, there seems to be a difference in the pump ram and pump bore dimensions, looks like the pump bore is the wrong size

Drawing says ream 3/8" and shows ram as 3/8".

1" stroke does sound too much for that engine, he did use 1" stroke for the larger horizontal pump but 1/2" stroke eg 1/4" offset is more likely. By comparrison my 2" Fowler is 3/8" bore x 3/8" stroke.

Edited By JasonB on 20/08/2019 20:41:07

Jason did you mean 1/2" stroke from a 1/4" offset eccentric? I think 1/2" stroke would work for the shown pump body, but not 1" stroke.

Yes Jeff, altered it now

You only need to look at photos of other engines to see what the offset is, look at teh gear behind the eccentric, no way is it offset by 1/2"

Thanks for the replies. I will now go ahead with 1/4" offset on the eccentric. The eccentric dimensions on the drawing are wrong then. Thank god for that. I've fabricated the body, but did not start on the eccentric yet.

This video shows the pump quite well, about half way through you can see that the ram lifts a little more than it's diameter so 1/2" stroke.

Thanks for the help Jason.