17 hp engine bogs down with my new pump. Do I need a bigger engine?

[chad22]

Hello. I bought this new pump on ebay and it is a bit bigger than the haldex I had. The shaft is actually a 5/8" diameter instead of 1/2" but that was no big deal as I went and got a 5/8" Jaw coupler.

The problem is it wants to bog down and almost kill the 17hp opposed cylinder engine that's currently on my home made excavator.

eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices

Do you think I need an engine with more hp? If so how much hp do I need to run this pump? lol

The listing says it's an SAE AA mount. But looks more like an SAE A mount.

Here's the specs per the listing on ebay.

Specifications



Rated pressure: 2900psi.

Displacement .3759 cu. In/rev

Shaft: ｽ keyed. (actually 5/8")

Ports: G1/2 inlet: G3/8俳utlet.

Rated RPM: 2000, Max RPM 4000

Part Number CB1A-F6SA

I'm thinking it may be a bit big for my 17hp engine to pull. But wanted to find out.

Thanks

Chad

 

[J_J]

A .4 cu in pump running at 3600 will produce about 5.5 GPM.

5.5 GPM at 2900 psi only requires about 11 HP.

You should be able to pump 8.5 GPM with a 17 HP engine using a .5 cu in pump at 3600 rpm and 3000 psi

 

[gengine]

Is the rotation of the pump the same as the old one?

 

[J_J]

What psi did you set the relief pressure?

If you run that pump at 2000 rpm, you will pump 3.25 GPM.

At a pressure of 2900 psi, it will take 6 HP

Have you install a hyd gage in the system?

What was the cu in of the pump you had before?

Was it a two stage?

What is the model number of the Haldex pump

 

[gengine]

What psi did you set the relief pressure?

I was just coming back to ask that!
Chad, if you don't have a hydraulic gauge, go buy one. JJ told me to get one a year or so ago, I finally picked one up last month, and it can tell you a lot diagnostically.

 

[chad22]

Thanks for the help. Good to hear that the pump should work with my engine. I do have a hydraulic gauge. I ordered it quite awhile back. I never did get it hooked up though and have since misplaced it somewhere at our shop. :laughing:

I went searching for it today but couldn't spot it. If I can't find it I'll just get another one when I go to town probably Monday.

By the way. Where in the hydraulic circuit should I hook the gauge?

I'm not sure on the cu of the Haldex pump but will have to see if I can get some numbers off of it. I do know it was a single stage pump though.

Chad

 

[chad22]

Is the rotation of the pump the same as the old one?

Yes it's the same rotation.

Chad

 

[gengine]

I was also wondering about open center pump and closed center valves. When does it try to kill the motor? When does the pump try to kill the motor, is it when you pull a valve lever or just starting the engine up? With a bigger pump, how about hoses striating the flow? Just scratching my head here...

 

[chad22]

I was also wondering about open center pump and closed center valves. When does it try to kill the motor? When does the pump try to kill the motor, is it when you pull a valve lever or just starting the engine up? With a bigger pump, how about hoses striating the flow? Just scratching my head here...

The motor runs fine when starting up and as long as no valves are moved. It's just as soon as you pull a lever on the valve it sometimes bogs down and other times it just just wants to die.

Chad

 

[J_J]

You haven't told us what machine this motor and pump is on.

Can you post the flow path from pump to tank?

You can't mix open center hyd systems and closed center valves, as the open center valves passes the fluid from pump to tank with all valves in neutral.

Closed center hyd fluid flows to the valve and stops, waiting on a lever to direct flow, and then the used fluid is sent to tank.

 

[chad22]

The flow path goes straight from pump into valve and out the other end of the valve and heads straight back to the tank.

The valve is open center.

The machine the pump is on is my home made towable excavator/backhoe.

The specs of the pump on ebay could be wrong too. I'm not sure. It's really windy out right now. But once the weather clears up. I'll get out there and get the numbers off the pump.

Maybe the .cu's of the pump is more than what's in the listing. I know my old pump is a baby compared to this new pump. lol

Thanks

Chad

 

[J_J]

If you go to a larger pump, and keep the same rpm, the GPM will increase and if the pump is capable of producing about 3000 psi, then the HP requirement will go up.

For instance you use a 1.0 cu in pump and 3600 rpm, the GPM will be about 15

15 GPM and a pressure of 3000 psi will require about 31 HP.

Now, you can run this 1.0 cu in pump at about 1800 rpm and produce about 7.5 GPM, and that will require about 15 HP

Tell me again why you want to run the engine at low rpm using the pump you have now.

Is it the noise level or longevity of the engine and pump parts, etc

 

[James Eric]

Chad,

They may have sent you the wrong pump. I just purchased the same pump with the same part number from Ebay but it has a 1/2" keyed shaft not 5/8" like yours. By the way, did you notice that the ports are stated as G1/2 and g3/8 in the listing?

 

[chad22]

Chad,

They may have sent you the wrong pump. I just purchased the same pump with the same part number from Ebay but it has a 1/2" keyed shaft not 5/8" like yours. By the way, did you notice that the ports are stated as G1/2 and g3/8 in the listing?

I think your right. They probably did send the wrong pump. One of the ports on this pump is G 3/4".

Good thing is I did get it to work at lower rpm. Although not working the best but at least it will let me dig up the last 2ft of the trench I need for my water line.

I'll still just keep this pump and use it for something else later. But then again I may wind up putting a bigger engine on the excavator/backhoe.

I was planning on putting the current 17 hp engine on my sears lawn tractor anyway.

Chad