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billybobbooth

Starter motor ring gear

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Bit of an odd question but ive found a company that do a 20 inch bolt on starter motor ring gear.

 

How easy would it be to bolt it to the back of any marine flywleel?

 

I realise its getting it strait but if you can get the bolting serface flat,with some very accurate measuring surly it couldnt be that hard? Also surly it would work out cheaper as the rings are only £140

 

The only issues i could see was getting the front of the starter to clear the flywheel if the flywheel is much bigger than 20 inch

Edited by billybobbooth

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Might find it hard to find enough 'meat' in the ring gear to drill through and I expect the gear will be hardened as well. could be easier to get a big pulley from the back of a washing machine drum, bolt that on and weld a pulley on the starter motor, tighten the belt with an idler pulley and a lever then loosen it if the engine fires. I was going to do this but not sure if it would work. I eventually rigged up a chain drive to the hand start sprocket but the strain broke the ratchet mechanism so don't try that.

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Might find it hard to find enough 'meat' in the ring gear to drill through and I expect the gear will be hardened as well. could be easier to get a big pulley from the back of a washing machine drum, bolt that on and weld a pulley on the starter motor, tighten the belt with an idler pulley and a lever then loosen it if the engine fires. I was going to do this but not sure if it would work. I eventually rigged up a chain drive to the hand start sprocket but the strain broke the ratchet mechanism so don't try that.

I read it that he had found a ring gear designed for bolting on so I would expect it to have holes in the ring already.

Bit of an odd question but ive found a company that do a 20 inch bolt on starter motor ring gear.

 

How easy would it be to bolt it to the back of any marine flywleel?

 

I realise its getting it strait but if you can get the bolting serface flat,with some very accurate measuring surly it couldnt be that hard? Also surly it would work out cheaper as the rings are only £140

 

The only issues i could see was getting the front of the starter to clear the flywheel if the flywheel is much bigger than 20 inch

Any pictures of the ring, how proud does it sit from the face of the flywheel

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I was looking at this

https://www.stationaryengineparts.com/Electric-start-components/

 

As the do a starter to match although i could prob find out the teeth gap and get a cheaper one to match.

 

My biggest concern was if my flywheels is bigger was depending on how much was having to cut effectively 1"×1" out the back corner of the flywheel. To clear the starter motor.

 

The other option was to just buy one of there flywheels and see if i can have it made to fit the national.

Edited by billybobbooth

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If you need to reduce the size of the flywheel to allow the ring gear to fit, you would have to remove the flywheel and have it machined.

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If you need to reduce the size of the flywheel to allow the ring gear to fit, you would have to remove the flywheel and have it machined.

Yes my plan is i have 2 options if it fits

 

. Measure my flywheel best i can

 

1. if my flywheel is over 22 inch fit a cummings engine starter ring as the internal size of the biggest ring they do is 22.3 inches

 

2 if my flywheel is under that cummings size fit a lister flywheel bolt on one and pray i dont need to machine much of my stock flywheel

 

Option 2 is preferred as i can do all the work in house as long as i can get the starter ring to sit level and in the middle.

 

Option 1 it will have to be machined to get it tight but not too tight to be pushed on.

 

The idea is that if i can find a

Cheap and easy way to do it it will make it far more of a viable venture as it will hardly get used for me but others may choose to convert theres if the system is cheap and reliable.

 

As alot of places quote 1k-2k to convert and that may seem right but seams very pricy too.

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Beware of chopping sizeable chunks out of the flywheel to get starter clearance. The flywheel has the mass and inertia that it does for a purpose. The main inertia comes from the outside rim which is why flywheels are usually thicker at the outside.. Adding the small ring gear will restore some inertia but not as much as is lost from the rim.

 

There are also potential torsional vibration issues but they are more complex than ensuring you have enough inertia to tick over in gear.

If you can get the flywheel macined to accept a ring gear on the outer edge that will marginally increase the inertia and is much the best solution.

 

Try talking to HPC gears. They will make one-off bespoke gears for reasonable prices. Somewhere on the board Martyn posted details of the gear tooth profile which you will need to match. It was in either the Listrr threads or the Gardner threads IIRC.

 

N

 

 

S

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Yes if i have to remove much of the flywheel i wont bother im hoping i only need to make it miss the starter by a few mm if it turns into more than this ill pos look into a spacer.

 

My hope is my flywheel is just bigger than the internal size of the cummings one really.

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NB Fern ( see other topic) used to have a bus dynamo V-belted to the JP2, you could motor the dynamo to start the engine, then once it was running the dynamo provides battery charging. The system was 24v and the dynamo was a 7in diameter CAV type. I have used a similar system but 12v on smaller engines . Worth investigating?

Our National has had a conventional electric starter fitted a few years ago but it was tres expensive, done by the then RN company.

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Yes i was trying to look into belted start which would be the best idea as i could use hand start but once turning over use the motor to power it, i just know my dad inlaw wouldnt be able to totally start it by hand. 24v wouldnt be so bad but the rest of the system items are 12v like fridge and all lights.

 

Yes i went to rn and wanted silly money. Unfortunately the job was quoted but then never finished due to a death.

 

So looking into cheaper options. I cant get in the engine room as im cutting wood in back cabin but will measure it in a bit.

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Would anyone know what sort of power dc motor i would need if going to use a 12v dc motor to turn the engine over ov with the decomposition open as would only need to spin the engine over once up to speed drop the decompression lever.

Found this http://www.labworld.co.uk/dc-motor-12v.html?gclid=CIGVrIeO7NACFSm-7Qod5qwLyw

 

Im not saying to use this motor but would i need one like this or bigger?

 

If that would work with a bracket to tention the belt i cant see it doing too much damage to the bearings if i ran it off the alternator front pully so was on a smaller pully wheel.

 

Was thinking turn engine over by hand kick motor in then once at speed drop decomposition lever shut off motor once started.

Edited by billybobbooth

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Beware of chopping sizeable chunks out of the flywheel to get starter clearance. The flywheel has the mass and inertia that it does for a purpose. The main inertia comes from the outside rim which is why flywheels are usually thicker at the outside.. Adding the small ring gear will restore some inertia but not as much as is lost from the rim.

 

There are also potential torsional vibration issues but they are more complex than ensuring you have enough inertia to tick over in gear.

If you can get the flywheel macined to accept a ring gear on the outer edge that will marginally increase the inertia and is much the best solution.

 

Try talking to HPC gears. They will make one-off bespoke gears for reasonable prices. Somewhere on the board Martyn posted details of the gear tooth profile which you will need to match. It was in either the Listrr threads or the Gardner threads IIRC.

 

N

 

 

S

Well said, I should have added that the machining would be a small recess for the ring gear!

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Would anyone know what sort of power dc motor i would need if going to use a 12v dc motor to turn the engine over ov with the decomposition open as would only need to spin the engine over once up to speed drop the decompression lever.

Found this http://www.labworld.co.uk/dc-motor-12v.html?gclid=CIGVrIeO7NACFSm-7Qod5qwLyw

 

Im not saying to use this motor but would i need one like this or bigger?

 

If that would work with a bracket to tention the belt i cant see it doing too much damage to the bearings if i ran it off the alternator front pully so was on a smaller pully wheel.

 

Was thinking turn engine over by hand kick motor in then once at speed drop decomposition lever shut off motor once started.

It will be surprisingly large. A 5 in CAV starter is of the order of 5 or 6 kW I think. You could roughly calculate what is needed if you knew the inertia of the flywheel and the speed you want to get it up to in a given time- say 3-4 seconds. work out the energy in the rotating flywheel and engine (1/2 Inertia x speed squared) and then divide this by the time and that will give you Watts if you use the right units.

 

The type of motor will need to be one that produces good torque at very low speed (because it has to accelerate the flywheel from a standstill or nearly so if you get it moving by hand) and yet does not go ballistic on no load. That means a universal motor or a series wound DC motor is out and you need either a compound or shunt wound DC motor. My motor stuff is way old so you would need to speak to an expert. It doesn't have to run long so cooling is not likely to be a problem.

 

The simplest approach might be to look at modifying the drive arrangement of a standard vehicle starter motor or Dynastart. Getting the thing sufficiently strongly mounted will also be a challenge- as said above there will be substantial torque reaction.

 

However, if you are going to turn the engine over by hand why not just hand start it?

 

N

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Dynastart strapped to the lining plank is an option we're looking at for an installation in a wooden boat. We'll let you know how that goes!

 

Dan

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However, if you are going to turn the engine over by hand why not just hand start it?

 

N

As stated i have no problem hand starting. The idea is so my dad inlaw can start it should he wish to use the boat or any one who cant start it by hand e.g. my wife.

 

Once its started its fairly easy to start again. But its got very good compression so if it ant turning fast when you drop the decompression it just stops there is no ill go over a few times even if you dont lift the decompression when shutting it of when it gets slow it will just stop dead.

Its all food for thought. Ill get measuring in a bit as a starter would be the best way if i can get a good ring thats close to my flywheel size, i thought i found a company that make bolt on starter rings that were in halfs but cant find them now

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A dynastart might do it but not belted to the alternator pulley it won't, it needs to be on the flywheel and you might as well machine it for a ring gear as a pulley. Starters are almost invariably series wound by the way but a rare few do have additional shunt fields. It's the right machine for the job so I wouldn't bother looking for an alternative.

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No help to the OP but a bit of reading I was doing last night indicates that some cars with auto Stop/start use the alternator to start the engine.

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No help to the OP but a bit of reading I was doing last night indicates that some cars with auto Stop/start use the alternator to start the engine.

That's a flywheel mounted motor/generator not something you can just bolt on and belt up.

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That's a flywheel mounted motor/generator not something you can just bolt on and belt up.

I don't intend pulling the car to bits to find out boat.gif

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That's a flywheel mounted motor/generator not something you can just bolt on and belt up.

Being from car back ground this is something i looked into but the electronics to do this isnt simple and its not use in a way to start a car its used to generate electricity by a way of engine braking and its also designed to runs sum aux items like aircon when the engine is shut down via electric or magnetic idle pullys ect. Its not a strait forward motor really used for starting engines but it is an area being developed to use for starting or assist starting.

Unfortunately i havent had chance to get the flywheel measured purly as i cant get into my engine room as these is i big amount of oak in the way.

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Some modern starter motors are geared, they work very well.  BUT the reduction ratio with a big flywheel will mean it is difficult to get the engine up to a good starting speed unless the motor is able to get it turning at a sensible rate.

 

Have you considered air start?

Edited by Boater Sam
added more

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On 11/12/2016 at 08:41, billybobbooth said:

It may not work was just ideas.

It won't work they are out of stock of the ring gear  ?

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