[modeleng] Re: Finding dead centres on a loco

  • From: "AndyA" <AndyA@xxxxxxxx>
  • To: <modeleng@xxxxxxxxxxxxx>
  • Date: Sun, 19 Feb 2006 16:34:07 -0000

Hi John
Could you take the front cylinder cover of and use a DTI acting on the
piston face? Ive done this myself a few times and found it to be the easiest
and most accurate.

Andy
----- Original Message -----
From: "John Pagett" <john_pagett@xxxxxxxxxxxxxxxx>
To: <modeleng@xxxxxxxxxxxxx>
Sent: Sunday, February 19, 2006 2:53 PM
Subject: [modeleng] Finding dead centres on a loco


Just to start something off...

I've got to determine the lengths of the rods which run from the return
crank to the expansion link on my Sweet Pea fitted with ouside admission
Walschaerts' valve gear. To do this I have to set the engine on front and
rear dead centre. I've seen the method where you mark a point on the wheel
and a point on the slide bar when approaching dead centre, rotate past dead
centre to the point where the mark on the slide bar is in the same place
relative to the crosshead, mark the wheel again and divide the distance
between the marks on the wheel to find dead centre.

First question "Is this the best way?"
Secondly, "how do you divide a curve into two equal parts?". I can do a
straight line with a rule and dividers, but as I see it half of the
construction space is in thin air outside the wheel!

Any thoughts gents?

TIA

JohnP

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