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Message |
    
richarddurgee
Senior Member
Username: richarddurgee
Post Number: 2203
Registered: 11-2001
| | Posted on Saturday, October 10, 2009 - 07:31 am: | 
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Lots a "Pumpin" Nuf-Sed.
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billschaller
Senior Member
Username: billschaller
Post Number: 301
Registered: 12-2003
| | Posted on Sunday, October 11, 2009 - 02:10 pm: |
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Great information. I had always thought that they only worked in one direction, but hadn't really thought about it. Also, in the dozen of years I have been going to flea markets, they are a lot harder to find now.
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richarddurgee
Senior Member
Username: richarddurgee
Post Number: 2210
Registered: 11-2001
| | Posted on Sunday, October 11, 2009 - 05:01 pm: |
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Bill, More trivia, your photo above shows the petcock with the oil cup, Gray was the only Co that had that feature made into its Oberdorfer pumps (I Believe), Obviously a very handy way to prime the water pump when needed, also nice to see the original accessory on the pump after very close to a hundred years !
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keith
Senior Member
Username: keith
Post Number: 262
Registered: 02-2002
| | Posted on Sunday, October 11, 2009 - 05:38 pm: |
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Someone explain to me how a gear pump can be reversed and yet pump the water in the same direction. The inlet and outlet are located central to the two gears. |
solarrog
Senior Member
Username: solarrog
Post Number: 378
Registered: 03-2002
| | Posted on Sunday, October 11, 2009 - 05:48 pm: |
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i BELIEVE IT WOULD REQUIRE SOME ADDITIONAL PIPING AND VALVES TO WORK |
richarddurgee
Senior Member
Username: richarddurgee
Post Number: 2211
Registered: 11-2001
| | Posted on Sunday, October 11, 2009 - 07:11 pm: |
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Keith it can't be explained !
To reverse an external gear pump the inlet and outlet have to be reversed in some manner.
http://www.liquiflo.com/v2/files/pdf/Gear_Pump_Basics.pdf
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kerrigan
Member
Username: kerrigan
Post Number: 28
Registered: 06-2008
| | Posted on Sunday, October 11, 2009 - 07:26 pm: |
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What happens to the direction of flow when the pump's shaft rotation is reversed? |
kerrigan
Member
Username: kerrigan
Post Number: 29
Registered: 06-2008
| | Posted on Sunday, October 11, 2009 - 07:29 pm: |
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Does the engine care if the water inlet and outlet are reversed? |
keith
Senior Member
Username: keith
Post Number: 263
Registered: 02-2002
| | Posted on Sunday, October 11, 2009 - 08:26 pm: |
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Pump
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ernie
Senior Member
Username: ernie
Post Number: 1068
Registered: 01-2002
| | Posted on Sunday, October 11, 2009 - 08:48 pm: |
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On a Gray the pump doesn't work in reverse.
When I reverse the engine in my boat the exhaust gets a lot louder when the cooling water is no longer injected into the exhaust. When I go back to forward you can tell without even looking that is is pumping water again when the exhaust quiets down.
The oil cup on the pump is to add oil so it will prime. The amount of water that cup will hold is no way enough to prime the pump. I still have the one from my Gray however I replaced it with a grease cup which is a lot easier to deal with. |
billschaller
Senior Member
Username: billschaller
Post Number: 302
Registered: 12-2003
| | Posted on Sunday, October 11, 2009 - 09:38 pm: |
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I would assume that to have it reversible, there would need to be a way to swap the inlet and outlet around, which would not be very hard. The ad said no check valves, not that other valves wouldn't be required. |
kerrigan
Member
Username: kerrigan
Post Number: 30
Registered: 06-2008
| | Posted on Sunday, October 11, 2009 - 09:57 pm: |
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It may make a difference if you're cooling the exhaust too. Was that a feature on all engines? Look at at the inlet and outlet of the pump in the photo. If they both go to the drink what happens when you rotate the pump CW? What happens when you rotate it CCW? |
keith
Senior Member
Username: keith
Post Number: 264
Registered: 02-2002
| | Posted on Monday, October 12, 2009 - 10:13 am: |
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I guess the bottom line is you are not in reverse for extended periods of time. Therefore you don't have to worry about cooling. It would be somewhat complicated to have a system where you need to change the cooling system, throttle down and change the timing and ignition on/off to reverse. I imagine that Oberdorfor's claim only referred to the fact that the pump can be set up to work in either direction, not that it worked with reversing an engine in operation. |
miro
Senior Member
Username: miro
Post Number: 396
Registered: 11-2001
| | Posted on Tuesday, October 13, 2009 - 09:17 pm: |
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The only time I've seen the Gray gear pump work when the engine is turning backwards was at the Calvert Show.
The inlet and the outlet were in a water barrel and the exhaust went straight out into the atmosphere.
So, yes they CAN run in either direction, but I'm sure that's not what the factory had in mind when they wrote the ad all those decades ago.
miro |
