I am building a gas powered hydraulic pump to run a tailgate sand and salt spreader. The spreader has two motors, 1 runs up to 10 GPM and the other runs 5 GPM. These are usually run off central hydraulics on the truck, but mine doesn't have the setup. The vendor for the spreader says I should need 15 GPM and around 1000 PSI to run both.

I am looking for a pump that I can mount to a 13 HP honda motor to run the spreader. I am having trouble finding a 15 GPM pump that also has the lower PSI. Seems like all the ones I find are 2 stage and I am not sure if that would work.

Does anyone have any pumps they would recommend. The motor will turn a max of 3600 RPM.

You dont need a special pump for the lower pressure rating...a pump rated 2500psi or 3000psi will work just fine....the rating is a MAX pressure...just set the relief valve on 1000psi.....a 1.15 cui/rev pump will give you about 15gpm at 3000rpm, and use 8.8hp....not concidered the volumetric inefficiancy at 1000psi....maybe about 10-15%....

Check if enegine have torque enough to run a larger pump on lower rpm for better fuel efficiancy....

Here are some useful simple formulas

http://www.airlinehyd.com/Know...c/Formulas/PumpH.asp

If you are going to use conventional valving system and the application does not require precision, a double pump combination(between 10/5 gpm@ certain PM rpm) can be used(whether gear/vane/piston type, whichever you prefer). If you are going to use fix displacement, you must have two separate relief valves.

For applications in mobile, I always recommend a variable displacement piston pumps, though more expensive, but power saving is better, controls are simplified, a lot of flexibility, and so much more advantages. Imagine comparing the valving/piping you need in this application. A single variable displacement piston pump can be run between 1000 to say 2000 rpm, you have so much flexibilty in controlling both motor speeds without too much power losses as well as the possibility fluid heating up is minimal(pressure drops across flow control valves/DCVs are minimum when swashplates swivels, especially with load sensing control option).

It is up to you to decide( cost and/or efficient) what to use, but don't be deterred by a possible complex issues when using variable pumps, they are simple, try studying the late Bud T's e-book, maybe you can find more info.

A double pump like this is what you need...
https://www.surpluscenter.com/...00&catname=hydraulic

1cui+0.5cui
Will give you the flow you need at 2200-2500 rpm
One relief valve on each pump....and two electric valves like this
https://www.surpluscenter.com/...37&catname=hydraulic

Double action optional for you, buy subplate separtely

https://www.surpluscenter.com/...-1&catname=hydraulic

And hirschman contact

https://www.surpluscenter.com/...57&catname=hydraulic

wire and plumb to you

I probably should have mentioned I also have a manual flow control valve that has on/off and two dials for speed of the auger and spinner. It is similar to this one, valve

It only has one feed in so the dual pump is probably out unless I abandon this valve and put two inline flow controllers.

Does it matter when the pump says 3000 RPM max and the motor will turn up to 3600 if you were full throttle? I like planning on running it at a lower RPM, just curious if I need to care?

When I look in the 1.1 to 1.2 sizes there are a couple of different brands on the suplus center site. Do you get a better pump the more you spend (prince) or can you get by with a cheaper dynamic or hydreco brand?

I think this one would work for a cheap option
dynamic

And this one for a more expensive option, https://www.surpluscenter.com/item.asp?UID=2009082821074265&item=9-1899-B&catname=hydraulic

What size tank would you recommend?

Thanks for all of your advice and help!!

Running two motors continiously will cause oil to warm up....Having valves that are rated 1.5-2 times higher than actual flow will definately help out....a flow divider will always be a source for heat....oil warm up is caused by resistans in circuit....basically a loss of pressure.....

3-5 times the pump flow is a common recommendation...but tank size depends on how you design it, how much tank surface area that are exposed to free air, (a circular globe will give the smallest surface area per USG, and a narrow tall box will give big surface area per USG), and also what operating temperatures there is....read at ebooks...
http://www.hydraulicspneumatic.../Article/True/39340/
It sounds like you are going to operate wintertime....how long are the operating sessions?.....8 hrs or 1 hr..._???

I would still go with the double pump instead of flow divider valve....IMO, it just makes it simpler, I also think that a flow divider valve is the first part in the system to malfunction...

EDIT
100F-130F (max 140F) is a desired operating oil temperature in the reservoir

It will probably run for 30 minutes on, then 15 minutes drive time, then run for another 30 minutes. So it won't be running constant and it will all be winter in Iowa so anywhere from -10 to 30 degrees.

I think I will have to use the flow control to manage the distance the spreader will throw the sand. On low it will spread it a couple of feet on high it could be 20 feet. It also controls the auger which pushes the sand to the spinner. So to much sand or not enough sand could also cause problems.