Having been involved with a 7¼" gauge single-ended "diesel" driven by a petrol engine and "floating batteries", I am interested in designing and building a 5" gauge diesel locomotive (Class 37?) which is powered by a petrol engine driving a generator (DC) or alternator (AC with rectifiers) which is then directly linked to the traction motors without any further electrical or electronic means, other than reversing. There would have to be a 12V battery (for starting?) but otherwise ALL traction would be from the petrol/generator set.
Anybody got any ideas?
"Diesel" power
Re: "Diesel" power
Sounds like there's no takers for your problem so here goes with some thoughts from a steam locomotive man. Fools rush in and all that!
I did research this some time ago. First port of call was the "Handbook for diesel locomotive enginemen" or something like that, that was issued to BR drivers.
Basically you will have problems if you just connect an engine driven alternator or dynamo to the traction motors since there will be no control of the voltage, unless you put in some electronic gizmo to control it. In full size locomotives, control is through the electrical equipment, the diesel engine being controlled automatically by the demand, so as the volts x amps increases the the throttle is opened and visa versa. If it wasn't like that then the driver would need to control it manually and the engine would almost certainly stall as soon as the train started to climb a bank, or it would race away once over a summit. I think the issue is due to the effect of 'back EMF' which is controlled in full size installations by controlling the field in both the generator and the motors. They certainly don't have banks of resistors to control the motors as used to be the case in battery electrics before the electronic pulsed systems came along. Not being an electrical engineer I don't understand the theory, let alone the practice, but before embarking on this scheme I would recommend researching it thoroughly. Surely someone has done this by now.
I suspect the floating battery idea is one of the ways round this problem.
There was a series in ME in the seventies I think where a 3 1/2" gauge petrol electric was described. this included the manufacture of the traction motors as well.
Best of luck with it.
Eddie
I did research this some time ago. First port of call was the "Handbook for diesel locomotive enginemen" or something like that, that was issued to BR drivers.
Basically you will have problems if you just connect an engine driven alternator or dynamo to the traction motors since there will be no control of the voltage, unless you put in some electronic gizmo to control it. In full size locomotives, control is through the electrical equipment, the diesel engine being controlled automatically by the demand, so as the volts x amps increases the the throttle is opened and visa versa. If it wasn't like that then the driver would need to control it manually and the engine would almost certainly stall as soon as the train started to climb a bank, or it would race away once over a summit. I think the issue is due to the effect of 'back EMF' which is controlled in full size installations by controlling the field in both the generator and the motors. They certainly don't have banks of resistors to control the motors as used to be the case in battery electrics before the electronic pulsed systems came along. Not being an electrical engineer I don't understand the theory, let alone the practice, but before embarking on this scheme I would recommend researching it thoroughly. Surely someone has done this by now.
I suspect the floating battery idea is one of the ways round this problem.
There was a series in ME in the seventies I think where a 3 1/2" gauge petrol electric was described. this included the manufacture of the traction motors as well.
Best of luck with it.
Eddie
Re: "Diesel" power
The last time I was in the railway museum at York I remember looking at a model loco that had been built following the full size practice. From memory I think it was 5" gauge but I could be wrong! The note in the cabinet said something along the lines, the gentlemen that built it did get it running but had problems with it over heating. He unfortunately died before solving the problems.
Sorry I can't be more specific maybe someone could add to this,,,
Sorry I can't be more specific maybe someone could add to this,,,
Re: "Diesel" power
Yes. The loco you are talking about was by Roy Amsbury. the engine (not the locomotive) was a Deltic and it was described in ME.
Eddie
Eddie
Re: "Diesel" power
I recall seeing this back in the '70's.
Go to 4:15 and see Bob Symes type 4. for inspiration...
http://www.youtube.com/watch?v=YfCWcjvG ... re=related
Go to 4:15 and see Bob Symes type 4. for inspiration...
http://www.youtube.com/watch?v=YfCWcjvG ... re=related
Re: "Diesel" power
Bob Symes' loco is powered by a Taplin Twin miniature marine engine. Compression ignition 2 stroke, fueled by ether. The smoke is from the lube oil mixed with the fuel - Castrol M from memory. There is obviously some control gear but the engine is very powerful for its size so it might not need a very sophisticated control system. Touch of brute force perhaps.
Eddie
Eddie
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Malc Young
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Re: "Diesel" power
On a full size diesel electric locomotive there is a piece of equipment called a 'load regulator', this is attached to the diesel engine governor and matches the engine horsepower to the electrical load on the main generator, this prevents the electrical load from overpowing the engine and stalling it and reduces the engine revs and therefore the generator output should the load be reduced. The load regulator varies the field strength of the main generator which is fed from the auxiliary generator. The auxiliary generator is regulated the give an output of 110 volts continuously regardless of the engine revs and as well as exciting the main generator supplies the power for battery charging, lighting, compressors, vacuum exausters, tractin motor blowers etc.
Malc.
Malc.