Chris's Diesbar Engine Build

[crueby]

Top notch! (and top lever and top operating rod too) ... Looking great Chris.

You were peeking!  I just was back in the shop filing the notches in the control levers!   


 

[Michael S.]

It looks like it will work. Pressing the rod disengages the cam. That’s how I saw it, too.

Michael

[crueby]

It looks like it will work. Pressing the rod disengages the cam. That’s how I saw it, too.

Michael

Great!  I tried to make mine look just like the original,  though mine is slightly  larger than absolute  scale, mainly to get room for screws.

[Michael S.]

Chris, making compromises is perfectly fine.

Michael

[crueby]

This morning I turned up the handles for the release levers. They have a 1-72 screw threaded into the base, head trimmed off, and the end of the lever was tapped to match.

Here is one assembled on the engine. In this picture, the post is engaged in the center horizontal slot in the block. The control lever is pulled forward, and you can see part of the notch in the bottom of the lever as it hangs down over the top of the block.

In this picture the handle was pushed back, pushing the post out of the slot, and the notch is down over the block, holding the lever in position so that as the eccentric turns and/or the valve is manually moved (by another lever not yet made), the post cannot slip back into the slot.

Next I'll make up the spring and its lever. The spring attaches to the rear of the base frame and sticks up behind this mechanism, with a rod coming forward to the base of the block, giving continuous pressure against the block so that when the post is engaged in the horizontal slot it cannot slip out on its own. Right now, without that spring, if I rotate the crankshaft, partway around it does slip out. The spring arrangement is on the original engine.

[cnr6400]

  I'd say you have a good handle on that assembly! (or two, in fact)  It's looking great Chris.

[crueby]

I'd say you have a good handle on that assembly! (or two, in fact)  It's looking great Chris.

Yup, starting to think I have a grip on this build!   

[Kim]

Very interesting indeed! I've never seen anything like this on any other engine.   

I'm sure you've covered this, but what was the purpose of releasing it from the eccentric?  Stopping the engine?  Reversing?  And you'd have to pull the handles on both cylinders to get it fully disengaged.

Kim

[crueby]

Very interesting indeed! I've never seen anything like this on any other engine.   

I'm sure you've covered this, but what was the purpose of releasing it from the eccentric?  Stopping the engine?  Reversing?  And you'd have to pull the handles on both cylinders to get it fully disengaged.

Kim

Hi Kim,


Its part of the reversing process. The single eccentric slips on the crankshaft, with two stops to limit its rotation. Each cylinder has its own throttle valve too. To reverse direction, both throttles are closed. One release is pulled and the manual lever, which I  have not made yet, on that valve is used to move the valve to the other end. That cylinders throttle is opened, causing that piston to drive the piston back the other way. The eccentrics will slip till they hit their stops for the other direction. The release lever is disengaged so the post can go back in its center slot as it comes by. Both throttles can then be opened, and the engine takes off again. The engineer has to pick which valve to manually move based on where the crankshaft stopped. Lots of steps to this dance! In later years, the Stephenson  style linkage replaced the Penn slip style with an easier to run engine.

And the other question  you asked, only one side would need to be released  since there are separate  throttles, assuming the proper one is picked for the crank position.

Hope that helps?


Chris
 

[Michael S.]

I recently acquired an engine that still needs restoration—a Sanderson Beam, I believe. I am currently looking into this model and have searched online for comparable ones to find references and examples for completing the build. In one picture, the valve gear appears to feature a mechanism for starting the engine—for instance, when it is at a dead center position. It also looks like there is a catch for opening and re-closing it.

[crueby]

Ah - yes!  Now that you mention it, I recall that the MEM Corliss engine has a release mechanism on the top of the valve links like that! This is the engine in the upper left corner of the forum home page. A number of members here have built versions of it, I did a scaled down twin version several years ago. Its been a while since anyone has built one here, about time someone did!     The plans are available here on the forum, as are several build threads.

In your picture, if that linkage is released, the hand lever on the rod below the cylinder could be used to manually move the valve for starting, then the link re-engaged for running.
 

[Kim]

Thanks for the excellent explanation, Chris!  That really helps.  I'm sure you said it early and it all just flew past me.  But I'm catching it better this time through!

Very interesting.  And probably rather error-prone!

Kim

[crueby]

Thanks for the excellent explanation, Chris!  That really helps.  I'm sure you said it early and it all just flew past me.  But I'm catching it better this time through!

Very interesting.  And probably rather error-prone!

Kim

I bet there will be attempts at my reversing this model that fail, go sideways, and flip over backwards! The engineers  on the Diesbar make it look so easy, but I'm sure  it's  not.

[Admiral_dk]

I believe it is one of those things, where a great teacher and loads of practice, makes it easy (if you aren't hard pressed for time or in an emergency situation) - the young man in Michaels video obviously pre plan and time every move to perfection (practise).

How long it takes to get there ...? 

Per            

[crueby]

Its well past Spring here, but today is Spring Day for the model. I made up the leaf springs and mounting plates for the release mechanisms on the eccentric arms. These springs will push against the lower ends of the arms, keeping the post on the link plate in the horizontal slot in the release blocks when the hand lever is disengaged. When engaged, the block is pushed back against the spring so the post comes out into the vertical slot, and the hand lever is held there by the notch in it that I showed yesterday.

Next I'll make the rods/yokes to connect the spring to the blocks. Also need to get a coat of paint on the springs and plates.