Advice on resetting Intake/Exhaust Valves on a Vertical Walking-beam Engine

[Mfoxchicago]

Good Evening Steamboaters,

The TULE PRINCESS has been down for almost two years. But, at long last we have located suitable valves to provide Intake & Exhaust steam to her single piston, vertical engine. The old valves were 37 year old 1” Hoffman valves. The replacement Hoffmans we ordered ALL turned out to be defective and after much hassle with the Factory, even their attempt to fix the defect produced 2x defective valves. We had to go looking for as close an alternate as we could find.

The new ones FINALLY acquired and installed. The new ones are 1” Watson-McDaniel valves. We got up steam and made her wheels turn today, but the valves are not in sync and the action is not fully reliable. The timing is off. Thought the old settings would be the same. Not so. New valves need tweaking into true reliable service.

To me, it seems the Exhaust Valve on the spent piston stroke should open slightly before the attack of the reverse direction Intake valve providing compression. Then the alternate exhaust valve should open at the top of the closure of the intake, allowing the alternate reverse intake to take over the compression/release stroke. My description may not be textbook, but I am sure ol’steamboaters will know what I mean. Especially, anyone of you Captains or Engineers that have experience with walking-beam style engines.

My Chief Engineer (a veteran helicopter line Chief) and I welcome your advise and insights on how we can get this timing issue addressed.

Thank you all for you time and consideration in helping us out.

[barts]

Does this engine have a variable cut-off gear, or can one select between different cams?

In any case, I'd start with the exhaust valves just opening at bottom dead center, and closing as late as possible. Compression should be limited since the engine turns so slowly.

- Bart

[Mfoxchicago]

Good Morning Bart, Thanks for the quick reply. I am grateful for your insightful comments. For TULE, there is no variable cut off gear. We have a manual cam stroke actuator that we use to get the wheels rolling, once we're moving and at hull speed we drop the eccentric arms which take over automatic timing action - then she just runs.

I appreciate your suggestion as to first setting up the exhaust timing at the top & bottom dead center. With these new valves, I've been setting the timing up with the piston in the middle stroke point. I understand better why that would not be the most appropriate starting point.

[barts]

So if I understand things correctly, you manually control admission - intake - events when starting out, and once the engine is running at speed, you let the cams handle matters. Those presumably cut-off steam prior to full stroke, reducing power somewhat but using less steam. The boat itself in conjunction with the paddle wheels acts as the flywheel.

How is reversing handled? Is there a reversing lever?

- Bart

[Mfoxchicago]

You understand correctly. David Sarlin (the orginal designer & owner) modeled his walking-beam engine from that of the SACRAMENTO (Sister vessel is the EUREKA) from San Francisco, CA. The old walking-beams were started in the same manner. The Chief Engineer would manually control take off action until clear of the dock and running at speed, then "drop the hook". And yes, the forward or backward motion of the vessel on the wheels serves as the fly wheel to avoid any top or bottom dead center lock ups.

For Reverse, my Engineer will reduce throttle, pop up the hook, then reverse the timing action and kick open the throttle to power stroke, a vigorous "back stroke" action brings the vessel to a stand still.