question about correcting error introduced by using straight slide in valve gear

question about correcting error introduced by using straight slide in valve gear

This topic has 2 replies, 2 voices, and was last updated 20 January 2025 at 15:56 by Chris Kaminski.

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20 January 2025 at 12:40 #778663
Chris Kaminski
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@chriskaminski64716
I have two drawings from K.N.Harris setting out how to correct error
introduced by using straight slide.
Both of them based on Greenly and mostly identical,
but for one dimension (that I have highlighted in red)

as far as I can see in one (from article about JMG) – “L” appears to be vertical, when vibrating lever is at FDC…

in another (from article about Radial gears) – it appears to be in line with vibrating lever…

which one is correct?

please (and why?)
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20 January 2025 at 14:56 #778694
duncan webster 1
Participant
@duncanwebster1
Which articles, without context can’t say?

When he says ‘correction’ it needs to be taken with a pinch of salt. Better than a straight slide, but curved can be better. KNH didn’t have the benefit of computer models, so couldn’t fully see the effect of various dodges. In any case, Heywood used the offset top joint when Greenly was still a boy in short pants.
20 January 2025 at 15:56 #778703
Chris Kaminski
Participant
@chriskaminski64716
Thanks Duncan,

1st article (Introducing the JMG Valve Gear) – starts in No 3205 vol 127 (13th Dec 1962)

2nd article (Radial Valve Gears) – starts in No 3432 vol 138 (7th Jan 1972)

Yes, I am taking it with a large pinch of salt.

Yes Heywood was first.

My question is – do I just fiddle with simulator until I get what I want (for straight slide), or…

do Heywood, Greenly, Harris, Webster can offer some suggestions 🙂
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