Speed control

[Southern SailorParticipant @southernsailor76583]

I am trying a new tack on this one.  Can anyone tell me how do you control speed on a twin cylinder (or multi cylinder for that matter) in line steam engine?

Thanks

[Southern SailorParticipant @southernsailor76583]

[Eric Moffat 1Participant @ericmoffat1]

G’day Brian,  I reckon there are only two ways to control speed on a steam engine. One is by adjusting the heat under the boiler i.e. reduce steam pressure.

Second is by reducing the steam supply from the boiler to the engine . Make sure your safety valve is in good nick if you use this method!!

 

[Gondolier88Participant @gondolier8892148]

Of Course if you have a slide valve engine you can also ‘link up’ using the reversing gear which uses less steam by expanding what steam is used more than full ahead or full astern.

 

Greg

[lyle gadsdenParticipant @lylegadsden69524]

Avatar, controlling steam on a twin or single cylinder is EASY ,( why all the experts?). You install a normal steam cock ( like your kitchen tap) in the line from the boiler or superheater in the lagged steam pipe to the steam cylinder piston(s). I have installed a cog on the spindle and the servo is fiddled with by removing the potentiometers, ( in early Model Boat issues , repeated several times in issues ), so the servo gives about 135 degrees rotation clockwise & rotation anti clockwise. On the servo disc you fit a large cog say 2.5 times diameter to the smaller cog on the stop cock spindle. You then gethobby chain drive around from each dosc to disc as simple as like a bicycle set up with rotation in either direction and beautiful progressive opening or closing of the steam supply , to totally and accurately regulate the throttle or steam supplty to the piston (s). It works so smoothly like the accelerator of say a car OR give her the gun (without any stalling, however you do not want to clown around too much with the grace of steam, fin. Lyle.

[HS93Participant @hs9317166]

brian what steam engine is it ? 

 

Peter

[Southern SailorParticipant @southernsailor76583]

Thanks Lyle, I suspected it would be something like that.  I find it strange that quite a bit is said about the reversing gear, but little about the speed control.  Also in photos, the steam cock is not really shown or referred to.

 

Greg, I am not sure what you mean by linking up with the reversing gear.  Can you expand on that?

 

Peter, I am going to tackle the TVR1A kit by Graham Industries as my first twin in-line engine.

 

Thanks for your input.  Happy sailing.

 

Brian

[HS93Participant @hs9317166]

http://www.mainsteam.co.uk/products/regulator.htm

 

this something made for the job, it will give you good control , you will also need a second servo to controle the valve gear for forward and reverse, it will make a nice set up in a boat, he sels them on ebay at times as well.

 

Peter

Edited By HS 93 on 04/10/2009 02:13:19

[HS93Participant @hs9317166]

Hi just re read your post and as it is only a single you are buying  it wil not be self starting so there is no need for the extra servo for reverse.

 

Peter

[JC Uknz 1Participant @jcuknz1]

If you are up to the engineering side of I would suggest that the best form of speed control is a variable prop propellor.   One of our Club members worked out his own design and wouldn’t use anything but it for his steam and petrol powered boats.   One of his boats has alternative steam and petrol motors which are interchangeable with about ten minutes work.

 

My own tentative efforts, yet to be tested in the water, come from an early Model Maker [ forerunner of Model Boats ].    The principle is to have the propellor blades mounted on a shaft which passes through the propshaft.  Rotating with that is a tube with slots machined in it to set the prop angle. This is moved backwards and forwards by the servo arm.  I suspect that it only gives forward and reverse unlike my fellow member’s version which gives variations from stop to full forward and full reverse.

 

The advantage of the variable prop is that you don’t have to stop the motor and re-start to change thrust direction.  My motor is a single cylinder oscilator so it is important it doesn’t stop!

[JC Uknz 1Participant @jcuknz1]

As far as single oscilators not self starting I am reminded of the WWII G45 RAF Gun Cameras which had a cunning set-up which when the motor was switched off the camera came to a stop at a fixed position … methinks maybe the answer for ossies

 

Another thought … while the normal steam motor is relatively slow rotating and uses a ‘large’ propellor … could it be that the Ossie needs to run fast so needs a smaller prop?

[JC Uknz 1Participant @jcuknz1]

A steam engine in a boat is like a railway steam engine so the same things that control speed with say Garden Railway engines would work for boats.

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