Self starting steam engines

[michael howarth 1Participant @michaelhowarth1]

I recently bought a small marine steam engine with 2 x 5/8" single acting pistons with 11/16" bore. The cranks are set at 180 degrees so that when one piston is at tdc the other is at bdc. The engine runs sweetly on low air pressure and will self start about 25% of the time. Unfortunately this is not good enough as I intend to use the boat on a river and a midstream stall would be mighty inconvenient.

Other than remaking the crankshaft so that the cranks are at 90 degrees is there any other wheeze i can use to encourage self starting?

Mick

[michael howarth 1Participant @michaelhowarth1]

[Tony HadleyParticipant @tonyhadley]

Two thoughts –

Send a copy of your message to Richard Simpson who writes the monthly Boiler Room column in MB magazine. Contact would probably need to be an email to the magazine editor or as a message to Colin Bishop, website editor.

As you say, 90degrees (quartering) is the normal method for self-starting a steam unit. For sailing in a high-risk environment, might it be worth fitting an auxiliary electric drive system. These were a simple on/off system fitted to some i.c. powered models as a 'get you home'. Whether a separate drive line or as some kind of clutch/gear system to disconnect the steam and engage electrical drive to the existing propeller shaft.

[Ray Wood 3Participant @raywood3]

Hi Michael

I'd agree with Tony about the auxiliary motor and prop to get you home if it stalls and the burner keeps going! Quartering only really works with double acting cylinders. The single actiing twin should self start in theory :-!

Regards Ray

[Charles OatesParticipant @charlesoates31738]

This is not my field, but I remember seeing an unusual arrangment. A gear wheel was put into the drive line, about 2 cm diameter. Then a simple push rod was connected to a servo so that it gave the gear a nudge to start it. I think he usually used the mechanism to start the model so it certainly worked.

[michael howarth 1Participant @michaelhowarth1]

This ai the plan of the engine I am referring to.

[michael howarth 1Participant @michaelhowarth1]

I have been playing around with it this morning and I have found that the only position for repeatable self starting is when No.1 cylinder is at 45 after tdc. I can achieve 100% self starting on very little air (5-10psi) at this setting. What does the forum think of inserting, say, a round headed rivet into the circumference of the flywheel with a very lightly sprung plunger bearing on the surface of the flywheel circumference (plunger could have say .020" clearance) to encourage the crank to stop in the desired position? Experiments continue.

Mick

[michael howarth 1Participant @michaelhowarth1]

I have received a suggestion on the MEW forum which sounds good and is pretty much the opposite of my idea above. It involves making a small disc which is fitted to the crankshaft and a dimple. of a depth yet to be determined, drilled in to the circumference of the disc. A spring mounted plunger with a tip that will match the dimple can then be mounted so that it engages the dimple when the crank is at optimum position for self starting. I wondered about the "click, click,click….." that will occur when the plunger engages/disengages but a teflon tipped plunger should sort that I think. Any thoughts on this very simple proposal?

Mick

[Andy StonemanParticipant @andystoneman15177]

Hi Michael,

What makes you think your engine will stall midstream, I think prior to making the changes your intending you might before trying a river for cruising carry out some steam testing of your engine out of the water.

You will gain more confidence in its operation. When your happy it runs well you'll gain more confident in it, after that try a few bath tub trials, if all goes well you know the next step

Andy

[michael howarth 1Participant @michaelhowarth1]

Thanks Andy. Perhaps my lack of confidence derives from a lifetime of falling foul of Sod's Law but your good wishes and advice are appreciated.

Mick

[Richard SimpsonModerator @richardsimpson88330]

Mick, There have been numerous ideas on this very theme. My own favourite is to use a controllable pitch propeller, they are being made in brass again by a supplier in China, but there are also reversing gearboxes to consider as well as an electric motor connected to the shaft that free wheels under normal operation and can be powered to turn the engine if it stops in a dead spot. I would love to see someone use the motor as a generator when it is being turned by the steam engine to charge up the battery!

By the way your disc with the hole and the plunger idea I am sure will sap a huge amount of power from the engine that will reduce running time as well as performance.  The electric motor idea will as well but it should have a lot less drag.

Edited By Richard Simpson on 15/12/2018 10:46:31

[michael howarth 1Participant @michaelhowarth1]

Nearly a year on but I have found the solution to a non self starter starting. It involves the use of a one way needle roller bearing (about £3) fitted on the crankshaft. A brass collar with a drop arm is made to fit over the bearing. When the engine is running the crankshaft spins freely within the bearing. When the engine stops running a "nudge" on the bearing from an appropriately placed solenoid linked to the drop arm will push the crankshaft off of TDC or BDC and enable it to start on application of steam.

If the idea is of any use to anyone, feel free to PM me for details.

Mick

[Andy StonemanParticipant @andystoneman15177]

Hi Mick

I made a get you home safe motor for the very same reason, it sat alongside the flywheel of the engine. Using r/c if needed to engage, This was enough to turn the engine over and self start again.

Andy

[Andy StonemanParticipant @andystoneman15177]

[Andy StonemanParticipant @andystoneman15177]

Hi Mick not the best pic, i'll see if I can track it down If your interested

Andy

[TelstarParticipant @telstar]

Hi Michael, Have you thought about a Kitchen/Kitchener? rudder. there is no need to stop the engine then. If I've got my facts right this type of rudder was used by the R.N. on steam Pinnaces. These had a single cylinder steam engine, so to go astern the rudder system was used.

A number of modellers (including myself) have made RC versions of this rudder

Cheers Tom

[michael howarth 1Participant @michaelhowarth1]

Hallo Andy and Telstar. I would love to see pictures of your starter and Kitchen rudder.

Mick

[redpmgParticipant @redpmg]

Simplest solution was one used by a member of the Johannesburg MBC – servo with a prodder fitted to it – nudged the flywheel on the Stuart 10 ( from what I remember – 25 years ago). seldom took more than a couple of prods to get it going

One of the modern smaller servos should do the trick – could be hidden/disguised easily enough

Edited By redpmg on 01/06/2019 20:52:05

[TelstarParticipant @telstar]

Hi. This shows a Kitchen rudder on a model. **LINK**

On you tube search kitchen rudder, and there is video of a full size one operating.

cheers Tom

[Andy StonemanParticipant @andystoneman15177]

Hi Michael,

They still used Kitchener gear on the workboats and cutters in my Day, diesel engine propelled though.Here is another option as I can't find the photo I was after showing more detail of the home safe motor. A is the Input shaft and B the output shaft, in between are two rollers which using the lever will give forward or reverse without stopping or reversing the engine.

Andy

Edited By Andy Stoneman on 02/06/2019 01:33:50

[michael howarth 1Participant @michaelhowarth1]

Thanks Andy. Pretty much the same as the reversing set up on my lathe.

Mick

[Andy StonemanParticipant @andystoneman15177]

Hi Michael,

Pretty simple I thought and not real hard to set up.Good luck with either way you try out.

Andy

[michael howarth 1Participant @michaelhowarth1]

 

Thanks for all the help and suggestions.

Mick

Edited By michael howarth 1 on 15/08/2019 09:34:47

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