glow plug engines

[John EdwardParticipant @johnedward60693]

is it me not looking in the rite place or is there no gearboxes so my large model can go forward then in reverse if needed and stop to let bigger models by

[John EdwardParticipant @johnedward60693]

[ashley needhamParticipant @ashleyneedham69188]

John, I am not an I/C man myself, but I think I am right in saying that there are no gearboxes for i/c boats….you just go jolly fast one way only!!    If you want variable speed and reverse, go electric.   Ashley

[Paul TParticipant @pault84577]

Hello John

 

Ashley is correct…..if you want a gear box for a glow engine then you would have to make it yourself……try using a reversing kitchen type rudder.

 

Paul

[John EdwardParticipant @johnedward60693]

thanks for the help boys but electric power does not give the same performance even when using 4 motors.

 

i will however post a set of plans once i have got it working

 

[Paul TParticipant @pault84577]

Hi John

 

What size and type of engine are you using?

 

Paul (the petrol head)

[John EdwardParticipant @johnedward60693]

hi paul sorry it took so long 2 get back 2 you long days at work

 

the engine is a supersport 21 marine

 

why do u ask ???

[Paul TParticipant @pault84577]

Hi John

 

The reason for the question is that years ago I came across a marine gearbox for an IC engine that fitted onto a 3.5cc unit, I dont know if it was a standard model or if it been adapted from a standard unit.

The gearbox worked just like a full size marine gearbox (a bit like an autu box on a car) and was worked by a single servo.

 

You could try talking to Prestwich Models http://www.prestwich.ndirect.co.uk/fsrv/gearbox.htm

or try building your own gearbox from robotic parts. http://www.ema-models.com/products/04255-multi-ratio-gearbox.html

but I am not sure that nylon gears could withstand your engine.

 

Paul

 

 

[ashley needhamParticipant @ashleyneedham69188]

Hi, I think that making a forward/reverse gearbox of the simple one shaft sliding cog type would be easy enough, the trick is the clutch, without which any gearchanging is doomed to stripped teeth and failiure…Thinking about it,a centrifugal clutch is the way to go…might be buildable on a small scale, but your enging would have to reliably idle, or at least slow down a lot sufficient to disengage the clutch, perhaps a larger that usual flywheel could be used, even using this as part of the mechanism??? the fat controllers liking for strimmer engines with built in clutches becomes apparrent!!!   Ashley

[John EdwardParticipant @johnedward60693]

hi paul i once saw a gear box in a verry impresive 1/25th scale model of an articulated lorry using a twin cilender desel !!!!!

[Andy NightingaleParticipant @andynightingale93292]

It’s easy on model cars, just about all out of the box cars do, but it would be damn near impossible on a marine engine. Not only would it probably do untold amounts of damage to the engine, if you did manage to get it to go backwards, due to the design of most powerboats, and the fact you’re using a very high powered engine, the back of the boat would dive in and fill it with water.

[John EdwardParticipant @johnedward60693]

with the introduction of a cog between the gear box and shaft should work and if eny moter can lower a model boat that is a meter long and sits 25 cm out of the watter under it would be good for a laf

[Paul TParticipant @pault84577]

Hi Andy

 

Good point about the boat flooding from the transom and I agree that the type of engines that I like to use would drag the boat under the water if used at full speed in reverse.

That is the problem with RC car gears as far as model boat are concerned as they are designed to work at high speed.

With a marine engine you need a gear box similar to a full size boat or an automatic car where the gearing for reverse is slow i.e. geared down.

 

Paul

 

Andy and John would you do us the kindness of filling in your profiles as we would like to know a little bit more about the people we are talking to.

Edited By The Fat Controller on 29/03/2009 08:17:49

[phill dParticipant @philld]

Simple answer for foward  and reverse on a model boat is to fit a Jet  unit with bucket reversing aid.

This way you can get reverse and it wouldnt damage the engine, also you wont drown the boat by it diving into the water.

The downward thrust in reverse would keep it afloat..

 

There are a lot of jets nowdays becomming fashionable again.

 

 

 

 

 

phill

[Author]

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