I came by a massive CAV dynamo last evening. Over a foot long & about 8" 
across, it is a two handed grunt to lift it & it came complete with its 
regulator. It lacks a pulley, but the input shaft is an inch thick. The 
massive double brushes are disposed at 90o to each other & there are only 
two sets.

It is 12 Volts & is "low speed" according to the plate. The regulator speaks 
of "batteries" and 25 amps.

It sits in two neat cast iron cradle brackets and is strapped to them by two 
flat hold down steel straps. Although rather automotive in appearance, I'd 
say it was not used in that context - aside from anything else like 
mountings, it lacks any oilyness! I wonder what its original application 
was?

How do I figure out what "Low speed" is? If I motor it & check the speed 
with a tachometer, will that be accurate enough?

It is an ideal bit of kit for an engine to drive, but can its output be only 
25 amps considering its bulk?

regards,

Kim Siddorn

On Tue, 22 Apr 2008 10:15:03 +0100, "Kim Siddorn" 
wrote:

>I came by a massive CAV dynamo last evening. Over a foot long & about 8" 
>across, it is a two handed grunt to lift it & it came complete with its 
>regulator. It lacks a pulley, but the input shaft is an inch thick. The 
>massive double brushes are disposed at 90o to each other & there are only 
>two sets.
>
>It is 12 Volts & is "low speed" according to the plate. The regulator speaks 
>of "batteries" and 25 amps.
>
>It sits in two neat cast iron cradle brackets and is strapped to them by two 
>flat hold down steel straps. Although rather automotive in appearance, I'd 
>say it was not used in that context - aside from anything else like 
>mountings, it lacks any oilyness! I wonder what its original application 
>was?
>
>How do I figure out what "Low speed" is? If I motor it & check the speed 
>with a tachometer, will that be accurate enough?
>
>It is an ideal bit of kit for an engine to drive, but can its output be only 
>25 amps considering its bulk?
>
>regards,
>
>Kim Siddorn
>

It's an early bus or truck dynamo by the sound of it.

If you can get the details off the plate, I'll look through my CAV service
manuals and see what I have for it. There are about 10 dynamo sheets IIRC.

We have a 60A 28V alternator sitting on the bench outside my office, AC203 CAV,
made to fit onto a Gardner bus engine and fully waterproofed.




Peter
--
Peter A Forbes
Prepair Ltd, Rushden, UK
peterforbes@prepair.co.uk
http://www.prepair.co.uk
http://www.prepair.eu

On Tue, 22 Apr 2008 10:15:03 +0100, "Kim Siddorn"
 wrote:

>I came by a massive CAV dynamo last evening. Over a foot long & about 8" 
>across, it is a two handed grunt to lift it & it came complete with its 
>regulator. It lacks a pulley, but the input shaft is an inch thick. The 
>massive double brushes are disposed at 90o to each other & there are only 
>two sets.
>
>It is 12 Volts & is "low speed" according to the plate. The regulator speaks 
>of "batteries" and 25 amps.
>
>It sits in two neat cast iron cradle brackets and is strapped to them by two 
>flat hold down steel straps. Although rather automotive in appearance, I'd 
>say it was not used in that context - aside from anything else like 
>mountings, it lacks any oilyness! I wonder what its original application 
>was?
>
>How do I figure out what "Low speed" is? If I motor it & check the speed 
>with a tachometer, will that be accurate enough?
>
>It is an ideal bit of kit for an engine to drive, but can its output be only 
>25 amps considering its bulk?
>
>regards,
>
>Kim Siddorn
>
Sounds like something from a bus or marine engine, except that 24V
would be more likely in that context and for that size. I've seen CAV
'low speed' dynamos before, but can't really help on what it means.
Serial/type number?

Tim

Tim Leech wrote:
> On Tue, 22 Apr 2008 10:15:03 +0100, "Kim Siddorn"
>  wrote:
> 
> 
>>I came by a massive CAV dynamo last evening. Over a foot long & about 8" 
>>across, it is a two handed grunt to lift it & it came complete with its 
>>regulator. It lacks a pulley, but the input shaft is an inch thick. The 
>>massive double brushes are disposed at 90o to each other & there are only 
>>two sets.
>>
>>It is 12 Volts & is "low speed" according to the plate. The regulator speaks 
>>of "batteries" and 25 amps.
>>
>>It sits in two neat cast iron cradle brackets and is strapped to them by two 
>>flat hold down steel straps. Although rather automotive in appearance, I'd 
>>say it was not used in that context - aside from anything else like 
>>mountings, it lacks any oilyness! I wonder what its original application 
>>was?
>>
>>How do I figure out what "Low speed" is? If I motor it & check the speed 
>>with a tachometer, will that be accurate enough?
>>
>>It is an ideal bit of kit for an engine to drive, but can its output be only 
>>25 amps considering its bulk?
>>
>>regards,
>>
>>Kim Siddorn
>>
> 
> Sounds like something from a bus or marine engine, except that 24V
> would be more likely in that context and for that size. I've seen CAV
> 'low speed' dynamos before, but can't really help on what it means.
> Serial/type number?

There were some large vehicles with lower voltage electrical systems 
made. Mostly a long time ago. Caterpillar made a D8 crawler with a 6 V 
system at one point:
http://www.armyvehicles.dk/caterpillard8.htm

Best wishes,

Chris