[modeleng] Re: Motor requirements

I have been looking at these motors as well John, especially the 24volt ones 
which seem less popular - possibly because car battery chargers etc are 
12volt, making the 12volt ones seem more attractive, so thank you for 
replying as well.  I am intrigued by your description of the use of the 
angle grinder though, but if I was to do something similar, could I use it 
for angle grinding again afterwards ??? :-D One of my first jobs has to be 
to check out the amphour ratings of the various smaller, lighter batteries 
that I can get hold of howeever, such as that on my rechargeable cordless 
drill / screwdriver as Al mentioned. I suppose that my mistake was not going 
up in to the 7+" gauges, then it would have all been so big that I would 
have had room for a small petrol generator on board as well .... ;-)

Please note that this last comment was a joke, as if I had done so, I would 
have used a lawnmower petrol engine instead ... IF !!! - another joke :-))

Tony.


----- Original Message ----- 
From: "John Baguley" <baggo@xxxxxxxxxx>
To: <modeleng@xxxxxxxxxxxxx>
Sent: Tuesday, May 29, 2007 9:42 PM
Subject: [modeleng] Re: Motor requirements


> At the 2½" Gauge Rally on Sunday one of the chaps had a little electric
> 0-6-0 shunter. The motor used was a 12volt 100W motor from an electric
> scooter. The motor was mounted vertically in the cab and used the bevel
> gears from an angle grinder to turn the drive through 90°. The final
> drive was by chain to all 6 wheels. The speed control was by a 35amp RC
> unit and as there was no room in the cab for any controls, you had to
> drive it by radio control as well!
> The scooter motors appear on Ebay regularly and seem to range from
> 80Watt to 120Watt in the 12 volt versions and more in the 24 volt types.
> The batteries used in the little shunter were only 4.5Amphour but it ran
> for quite a time as people queued up to have a go. Had a fair turn of
> speed as well.
>
> John
>
> Tony Wells wrote:
>> Well, I have finally surcumbed to the lure of the loco, and gone loco! My 
>> 3.1/2" gauge train now has a chassis, and both front and rear bogies, all 
>> in wood in true Richard Blizzard fashion though, so perhaps I should not 
>> be mentioning it here .... <VBG>
>> It is a scratch built 4-6-2, with 3-axle tender, all to be made from 
>> polished hardwoods, and not "hard words" as I just mistyped - they will 
>> come later! As I am working from the bottom up, I need to decide on the 
>> drive train next, so as to be able to design the body around it. The idea 
>> is for it to look like a steam loco, but be electrically driven, but more 
>> Basset Loake than Hornby Triang, hopefully! With an overall length of 
>> nearly 30", at least I have given up on the Basselt Loake clockwork motor 
>> idea though .... I am therefore thinking of putting a battery (or 
>> batteries) in the tender, with a disguised power cable through to an 
>> electric motor in the loco proper.
>>
>> Chatting to Al and Tel off list, I have come round to the idea of either 
>> a cordless electric drill or a recycled windscreen wiper motor, though 
>> whilst out shopping today, I saw some of the big 6-volt zinc lamp 
>> batteries, the ones (very) approximately 2" square and 3" high, for only 
>> £2 each and so may look into a 6-volt motor as well. I had thought about 
>> trying to find such as a small motocycle battery to fit into the tender, 
>> but decided that the additional weight made matters worse, not better, 
>> taking me into the lands of diminishing returns, incidentally. My problem 
>> is that while I have the bit of garden where the fruit trees are for some 
>> track, it is only 30' x 40' at the most, and so it would be a very twisty 
>> one at this size, round those trees, and so what design speed should I 
>> aim for please, so that I can determine how powerful a motor will be 
>> required?
>>
>> >From my working days, the clearance times for pedestrian crossings were 
>> >based on 1.2 metres (4 feet) per second, so should my train go faster or 
>> >slower than that, bearing in mind the lack of long straights where an 
>> >express could be wound up to maximum speeds? Should I be able to keep up 
>> >/ catch up with it in the event of an accident, such as when Unka Jesse 
>> >fell off his and could then only watch it disappear into the distance 
>> >until it (literally) ran out of steam ? As my driving wheels are 2.1/2" 
>> >diameter, I did a bit of mental arithmetic to work out that at 3mph, a 
>> >brisk walking pace but not rushing, the wheels would be doing around 
>> >225rpm.
>>
>> If I was to use a cordless drill with a natural speed of 900rpm to 
>> 1,000rpm, it would need to be greared down rather than using the standard 
>> sort of speed control, as these are inclined to over heat if used for a 
>> prolonged period of time. I would need a pulley ratio of 4:1 if I was to 
>> use the flexible drive belt that I am looking for. 1" to 4" would give me 
>> problems in housing the 4" pulley, whereas 1/2" to 2" might well give me 
>> slippage problems on the 1/2" one, however. Physical gears has (for me) 
>> the problem of achieving alignment as well as maintaining it due to 
>> possible moisture movement of the timber frame and chassis. This as well 
>> as being far noisier, though nylon gears might get around that if they 
>> could take the loadings.
>>
>> I am open to any help, ideas and suggestions that the Group may come up 
>> with, please, but precision engineering is just not possible for me I am 
>> afraid, as bittter experience has shown far too often.
>>
>> Thank you,
>>
>> Tony.
>>
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>>
>>
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