Petrol electric

[Phillip GrantParticipant @phillipgrant40491]

Does anyone have any ideas/information on building a petrol electric loco? I am considering a small electric start petrol engine driving a 55 Amp 24v alternator and thence to drive 24v electric motors (e.g. 2 @ 450w).

[Phillip GrantParticipant @phillipgrant40491]

[Ian S CParticipant @iansc]

Phillip, you'r proberbly looking at 3.5 hp minimum to drive the alternator to full out put, or about 2.5hp for your 900W of motor. For small generating systems I work on 50% efficiency, or worse. I have a 12V Lucas alternator (think its 45W), it's driven by a little Villiers 2 stroke off an old lawn mower, I can draw about 200W continuos, or 400W for a few miniutes, any longer and the motor siezes, the motor has no cooling fan. You would be best with a little 4 stroke. Can't tell you anything about the locomotive side of things, but I imagine it will be a shoe horn job fitting it all together. Ian S C

[Phillip GrantParticipant @phillipgrant40491]

Thanks for the info, Ian. Have youused any control gear between the alternator and the motor or direct coupling. There seems to be a school of thought that puts control gear in to protect any back-current from the motors from damaging the diodes in the alternator.

[Phillip GrantParticipant @phillipgrant40491]

Well,,, to any readers interested, I did a bit of local research here in Australia and there are a few petrol electrics successfully running here. I thank the locals for their help and am now working on my own Petrol electric armed with the knowledge that they have passed on.

I will be using a 6.5 h.p. electric start engine (resurrected from a now, unused go-kart) to drive an unregulated alternator (85amp). The output of the alternator will then be fed directly to the motors mounted in the bogies. The alternator is energized by the use of a Pulse Width Modulator (speed control). The PWM doesn't need to be able to handle any great loads as the rotors of alternators only draw a few amps,,,, so a small unit will be OK.

There are some pitfalls that some builders have had and they have been kind enough to pass their knowledge on to me. As this is a "new" idea, several club members are watching with interest.

[Phillip GrantParticipant @phillipgrant40491]

My "beastie" went for it's first run today. Delighted with the performance. 12 hp electric start motor driving a 12v alternator — for the ancillary equipment etc and a main alternator — a modified older type Lucas (85amp) which in turn supplies power for the 4 x 250W motors (one per axle making it a true BoBo).

The petrol motor barely got much above a decent idle while the train moved along at between 8 and 10km/h uphill and down-dale. The train was in use by a few people throughout a period of 3 hours and the main alternator stayed luke warm. The 12v ancillary alternator was warmer.

After today's tests, I think we may have one or two converts who might modify their battery electrics.

[doubletopParticipant @doubletop]

One of our guys has done a diesel electric with a 3 cylinder diesel engine from a small tractor. I'm not a fan of some of the lawn mower jobs but this really sounds the part, particularly when pulling away.

Pete

[Ian S CParticipant @iansc]

On my Kubota powered alternator, if it is over loaded, it shuts down, after the load is removed, it is required to restrike, ie either increase revs, or apply a voltage. Under normal use this set up does not need a battery.

The alternator has a 100 mm pulley, and is driven via an A section v belt from a 125 mm pulley on the motor. I have a 75 mm pulley I would like to try on the alternator, but can't be bothered with the mods required(or a shorter belt).

Ian S C

[Ian S CParticipant @iansc]

Here is the alternator unit, it's mounted on a home made sack barrow, that is arranged to be towed as a trailer behind my bike. Ian S C

[doubletopParticipant @doubletop]

Ian

OK somebody has got to ask. Why?

What do you use it for that you need to pull it behind your bike. Do you now have a petrol/diesel electric bike?

Pete

[Ian S CParticipant @iansc]

Mainly for something to do. It went along to the local A&P Show, to our machinery club display, Where a number of odd machines turn up, like a chainsaw sharpener that is operated by a vacuum windscreen wiper unit powered by a compressor driven by ( I think) a Sutton 4stroke motor.

Have thought of electrifying the bike, I have got a motor that would do it.

Ian S C

[doubletopParticipant @doubletop]

Ian

All very Kiwi, where's the #8?

Pete

[Ian S CParticipant @iansc]

Hi Pete, didn't forget the #8, if you look carefully, you will see a guard over the muffler on the far side of the motor.

Ian S C

[Neil WyattModerator @neilwyatt]

That had me running for Google!

Neil

[doubletopParticipant @doubletop]

Ian

You've got to do the bike!! Then they'll understand what #8 is all about

Pete

[Ian S CParticipant @iansc]

Number eight engineering is a Kiwi thing, it's the "art" of building,making things with what ever is lying around, including #8 gauge fencing wire (the wire that's used these days is high tensile #10 gauge).

Ian S C

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