Curtiss 75 part id
- Thread starter yaarge
- Start date
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MiTasol
1st Lieutenant
Interesting part and in great condition but you have me confused.
I suspect that English is not your first language as some of what you wrote looks like it was translated in to English by computer
Some more photos from different angles would probably help.
Firstly there appears to be what could be a part number cast in to the flange below the # 483 - what does that say and are there any other numbers or inspection stamps around the flange? Photos please if possible.
Secondly - which model of Hawk 75 did this come from as some had Wright R-1820 engines and some had P&W R-1830 engines and there were multiple sub-model engines involved.
Thirdly, and the reason I think your post was computer translated, is the statement part of supercharger vacuum pump. Superchargers do not have vacuum pumps so I am guessing you mean part of the vacuum pump drive mounted behind the supercharger. I hope that translates properly.
You say On the engine diagram there is a similar looking assembly. Can you please photograph that part of the diagram so that I can see what your diagram actually shows.
I suspect that English is not your first language as some of what you wrote looks like it was translated in to English by computer
Some more photos from different angles would probably help.
Firstly there appears to be what could be a part number cast in to the flange below the # 483 - what does that say and are there any other numbers or inspection stamps around the flange? Photos please if possible.
Secondly - which model of Hawk 75 did this come from as some had Wright R-1820 engines and some had P&W R-1830 engines and there were multiple sub-model engines involved.
Thirdly, and the reason I think your post was computer translated, is the statement part of supercharger vacuum pump. Superchargers do not have vacuum pumps so I am guessing you mean part of the vacuum pump drive mounted behind the supercharger. I hope that translates properly.
You say On the engine diagram there is a similar looking assembly. Can you please photograph that part of the diagram so that I can see what your diagram actually shows.
- Thread starter
- #3
Hello thank you for your reply. English is my first language, hopefully any lack of clarity is down to my poor knowledge of engineering and ww2 planes 
. I have attached photos as requested and an information card supplied by seller. I bought the piece at a militaria fair at the weekend.
Show quoted text
. I have attached photos as requested and an information card supplied by seller. I bought the piece at a militaria fair at the weekend.Show quoted text
Attachments
- Thread starter
- #4
The smaller stamped numbers are 1 (or7) 8192. There is a stamped circle with 17 in it next to this. The raised eroded numbers appear to be 18573-13?. 423 is stamped further to the right. There is a small single 2 stamped on the other side. I cannot find the diagram referred to in my first message unfortunately. Thanks
MiTasol
1st Lieutenant
Thanks and no problems with the lack of specific knowledge - I am sure that in your field you know infinitely more than I do.
I do not have any R-1830 parts lists earlier than 1943 when the engine had been in production for 11 years and undergone many changes (and a 50% increase in power) but what you have appears to be an earlier version of this part which does also drive the vacuum pump (well spotted).
Unfortunately the parts are not all drawn from the same angle but the shape of the gasket and gear item number 8 (tachometer drive gear) are both very distinctive and limited to this component so your overall identification was correct. This item is mounted on the rear crankcase behind the intermediate rear crankcase which mounts the carburettor and much of the supercharger.
These three drawings show the area quite well. I cannot give you its correct title but it would be something like tachometer and vacuum pump drive.
The vacuum pump provided suction for instruments and, on some aircraft, both suction and low pressure compressed air for operating the de-icer boots on the wing and tail leading edges.
The R-1830 model fitted to the H-75 aircraft also had two drives for gun synchronisation which are not shown in these diagrams.
I do not have any R-1830 parts lists earlier than 1943 when the engine had been in production for 11 years and undergone many changes (and a 50% increase in power) but what you have appears to be an earlier version of this part which does also drive the vacuum pump (well spotted).
Unfortunately the parts are not all drawn from the same angle but the shape of the gasket and gear item number 8 (tachometer drive gear) are both very distinctive and limited to this component so your overall identification was correct. This item is mounted on the rear crankcase behind the intermediate rear crankcase which mounts the carburettor and much of the supercharger.
These three drawings show the area quite well. I cannot give you its correct title but it would be something like tachometer and vacuum pump drive.
The vacuum pump provided suction for instruments and, on some aircraft, both suction and low pressure compressed air for operating the de-icer boots on the wing and tail leading edges.
The R-1830 model fitted to the H-75 aircraft also had two drives for gun synchronisation which are not shown in these diagrams.
- Thread starter
- #6
I understand the broad function of engine parts, but aero engines are particularly complicated so this is a real help. Thanks again for your time and expertise 
MiTasol
1st Lieutenant
No problems - all of us here are always learning new things - even us old fellas that have been working in aviation for well over 60 years
