Ken, et al,
There is a very good aricle in the current G1MRA magazine on Stephenson's
Link by JvR--it's part three of a series and refers to the following
concern raised by Ken and relates how Aster attempted to solve the problem.
""I am very short on space below the boiler. In fact, the model that you
see has eccentric links that would hit the boiler in full gear""
My Email does not suggest that I understand any of this.
Geoff
Steve,
>
>Thanks,
>
>The light green part (hard to see & vertical) is the hanger which supports
>the eccentric links (purple). The slightly darker green horizontal part is
>the lifting arm, which raises and lowers the hanger (and therefore the
>eccentric link) as the johnson bar is moved. I am hoping our terminology is
>similar.
>
>As far as I know, the typical Stephenson motion has the eccentric links
>pivoting around the link block. The motion of the link block drives the
>valve through the rocker. The amount of motion is controlled by the location
>of the link block in the eccentric link as the eccentric link is raised and
>lowered by the lifting arm and hanger.
>
>If there is another method, I would be really interested in seeing it, as I
>am very short on space below the boiler. In fact, the model that you see has
>eccentric links that would hit the boiler in full gear. I am still
>contemplating going back to slip-eccentric as it's going to be a squeeze to
>get all of the stuff below the boiler and between the frames. I spent last
>night looking for ways to prevent hitting the boiler and ended up shortening
>the eccentric rods by quite a bit, which seems to help. The motion still
>appears to be OK, although with a bit more distortion between forward and
>reverse than I would like to see. But I'm not entirely sure on how to
>interpret the diagrams. Still learning.
>
>The worst parts to make is going to be the eccentric links. The rest of the
>pieces are mostly connecting links and rods. I am planning on equipping my
>mill with CNC controls and that should make the curved parts a lot easier to
>make. No rotarty table needed and less file work.
>
>Once I get comfortable with the position of the parts and the motion of the
>gear (and time allows) I am planning on posting an animation of the valve
>gear. I did a few frames last week as a test and it looks really nice.
>
>
>Ken
>
>> -----Original Message-----
>> From: [EMAIL PROTECTED] [mailto:sslivesteam@;colegroup.com]On
>> Behalf Of steve boylan
>> Sent: Tuesday, November 12, 2002 7:08 AM
>> To: Multiple recipients of sslivesteam
>> Subject: Re: American valve gear pic
>>
>>
>> Ken,
>>
>> You wrote:
>>
>> > I just posted a jpeg of a preliminary model of the valve gear for my
>> > American project locomotive. Take a look here:
>> > http://moosedog.home.mindspring.com/ at file American valve gear.jpg &
>> > American valve gear 2.jpg.
>>
>> Looks really good. A couple technical questions: is the light green
>> lever at the top the lifting arm? And it looks like you're lifting the
>> links rather than the blocks, right? (Not that it makes a difference, as
>> long as it works!)
>>
>> Yeah, it looks like a lot of eensy-weensy bits, but not outrageous.
>> Personally, I'm just happy e-rings come in sizes down to a .040 shaft ...
>>
>> - - Steve
