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Chronometric tach


Cyborg

Well Known and Active Website User
VOC Member
Can anyone hazard a guess as to what this might be from or direct me to someone who may know? It doesn’t have any numbers on the face. The case has a 7 and an odd symbol. 0A305E76-D7D0-483E-8854-EDC229EF72F1.jpeg
7446A090-B63D-4251-99AD-1258FD07D72E.jpeg662A9502-259B-48A2-82FF-0A354BD7BE92.jpeg91820740-04BB-470C-AA7C-E3AD3D9D1F04.jpeg
 
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Whiteshadow15

Active Website User
VOC Member
I can’t help you with any information but I also have a similar gauge with no face numbers and a mark on the case. The back has “RC115” etched into it which would be a lightning model but not sure since it’s not an actual stamping.
 

Attachments

Cyborg

Well Known and Active Website User
VOC Member
Well... I suppose if you could establish whether or not it is CCW rotation, that would narrow it down somewhat.
 

Cyborg

Well Known and Active Website User
VOC Member
I wrote to a fellow here in Canada who does restorations and his comment was:
Your yellow face instrument is interesting as I have not seen a prewar (Smiths MA) face before with a yellow face.
but that’s about all he could tell me without inspecting it.
 

vin998

Well Known and Active Website User
VOC Member
VOC Forum Moderator
Problem is in the last 25+ years new faces have been printed by quite a few resources. One chronometric repairer in Nottingham even has the original Smiths printing equipment which he uses to make new faces with white or yellow print. So anything turning up today could be real or replica. Who knows?
 

Cyborg

Well Known and Active Website User
VOC Member
In my case, the tach was squirrelled away long ago, so unlikely it has a replica dial. The insides look like they haven’t seen the light of day since before WW2. It seems odd to me that there are no numbers on the dial, although from what I understand they can be a little cryptic at times anyway. Assuming I know what I’m looking for, it doesn’t have an idler gear on the drive, so it’s not a CCW unit. Again, it’s an assumption, because I know nothing about chronometric instruments. I suppose if I figured out the ratio, that might narrow down what it came off. The history is unknown... it arrived along with Vincent, and Norton OHC bits, but that doesn’t necessarily mean it was from a Norton.
 

davidd

Well Known and Active Website User
VOC Member
I have one of these tachs also. It was quite normal not to have a number on the face of the instruments. Here is a Black Lightning speedometer at the 1949 Earls Court show:
2749 02.PNG
It does not really matter what is inside if you send it to be checked and cleaned. The person doing the work can interchange parts to meet your needs.

David
 

Cyborg

Well Known and Active Website User
VOC Member
So am I correct on my assumption that if it was... say a RC115, there would be an idler gear somewhere on the drive which makes it a CCW rotation?

If driven with a drill, what happens if it is driven in the wrong direction momentarily? Does that eat gears?
 

Robert Watson

Well Known and Active Website User
VOC Member
If you drive it with a drill, it won't eat gears, If you drive it with the drill in reverse (A #2 Robertson head works well) it should run the instruments as set up for a Vincent. Remember that Vincent tach drives run opposite to most British iron......
 

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