Gear pump

[Brian Rupnow]

Here we are as promised, driven by my side valve engine. Chuck fellows had asked in an earlier post if this pump would be suitable to pump fuel. I told him that I didn't know, but I would try it with water instead of oil when it was finished. I substituted plain tap water for the oil, and it pumped plain tap water at the same rate it was pumping the oil.
[ame]https://www.youtube.com/watch?v=VvsOyoBthuo&feature=youtu.be[/ame]

 

[gbritnell]

Sorry Brian,
It will limit my responses!
gbritnell

 

[Brian Rupnow]

Sorry Brian,
It will limit my responses!
gbritnell

Nah George--I'm sorry. My bad. I post on 3 forums and somebody on all 3 has warned me about the fact that my tooth form is not right for a pump and I shouldn't expect any pressure. I must have taken my ugly pill this morning. When I grow up, I want to be as good a machinist as you are.---Brian

 

[Brian Rupnow]

And should anyone want to build this pump for themselves, just keep your tolerances fairly tight, and don't expect it to be a high pressure pump.---Somebody let me know if the download link works, please.---Brian
http://www.mediafire.com/download/0pdg7jfpx3qnvd9/GEAR_PUMP.zip

 

[Swifty]

Great job Brian, you certainly proved what you set out to do.

Paul.

 

[Brian Rupnow]

I must have taken my grumpy pills this morning, because I gave a couple of grumpy a$$ed responses in this thread. I apologize. Generally, I'm a lot nicer.---Honest!!!

 

[Lathejack]

Hello Brian.

A very interesting thread. I have long been fascinated with gear pumps, and it's been one of those projects I planned to have a go at one day.

So this may spur me on to finally have a go, just as your bicycle dynamo project did.

I wonder, can you feel even the slightest pressure if you put your finger over the oil pipe outlet while the pump is running?

I have hoped to make one that does produce some pressure, as I plan to use it in an I.C. engine. They do require close clearances all round and are certainly trickier to make successfully than a plunger pump is.

I remember I once bought a new oil pump for a 1975 Triumph Trident motorcycle I was rebuilding. This was a double gear pump with scavenge and feed pump gears. It was a new non genuine pump, so I bench tested it first. It was totally useless, being unable to develop any pressure at all, the internal clearances were just too big.

I stripped, cleaned and carefully reassembled the old original genuine Triumph pump, and when bench tested this was light years better than the rubbish new one. When refitted to the engine it produced 92 PSI at idle.

I am actually working on the refurbishment of a full size gear pump at the moment for a friend. This is from a 1940's A.E.C. double decker bus he is restoring. It is powered by a straight six diesel engine. I have noticed that the edges of the teeth on one side of one of the gears have a slight bevel. The edges should be sharp, so that's one area where pressure will be lost.

Anyway, I am off to find suitable materials for my own gear pump.

 

[Brian Rupnow]

Lathejack--Yes, when I block off the flow with my finger there is "some" pressure, but not a lot. I am going to investigate a "lip seal" as a replacement for the o-ring. It sticks in my mind that some lip type seals are sized to be almost an exact interchange for o-ring seals.---Brian

 

[bmac2]

Cool pump. Looks like it would defiantly keep a water cooled engine happy. Um . . . One little thing . . . Please tell me that’s not what your tap water looks like.

 

[gus]

Brian,
The picture in post #23 which shows the gears in place looks to me like it will cause a problem. The reason being is that the gear teeth seem to be too thin and won't seal when rotating. The mechanics behind this type of pump is when the gears are rotating they carry the oil around the inside of the housing. Once the oil gets to the opposite side of the pump the close meshing of the gears seals the exit route for the oil and pushes it through the outlet.
To have any kind of pressure efficiency all of the dimensions need to be as close as possible, O.D. of gears to housing, width of gears to cavity, and mesh of the gears.
gbritnell

Hi Gbritnell.
You are right.
Been putting together Hydraulic Power Packs for the 200 ton Deep Draw Presses.It is true that gear profile is thicker,higher and mesh very close to give very good sealing with the hydraulic fluid to prevent leak back.For high pressure you sure need this precision. For liquid transfer,Brian's gear pump worked well with positive head. The test comes with negative head.
Will have to DIY a gear type lube pump for the Howell V-2. Will be fun.
for hydraulic pumps. Brian has demonstrated his gear pump moved oil.

 

[ShopShoe]

Brian,

Thanks for another interesting project with well-documented post. You seem to be on a roll with several things right now. I like all of 'em.

--ShopShoe

 

[vederstein]

Brian,

Congrats on your success.

Twelve years ago I was tasked at work to design a low cost hydraulic pump to develop approximately 1000 psi. I initially started with a gear pump design with limited success.

Eventually I went to a geroter (look it up) and stuck to the design guide's recommendation. Again limited success. It was only after further R&D adjusting rotor clearances did I meet then exceed my goal.

So I can appreciate your accomplishments with what you've done.

Again, congrats.

...Ved.