I gotta get rid of this battery destroying electric-hydraulic pump on my dump trailer. ---- wanting to put a gas engine driven hydraulic system in it's place. Thinking of 8 hp b&s motor, a medium size hyd. pump, res. big enough to run 2 long stroke cylinders, and a control valve. ---- also the cylinders on this trailer are 2-way,---power up--power down.
Thinking 8 hp should be big enough to run the pump.
Opinions?? --- suggestions?
The battery does NOT charge from the truck ---- They claim it s'posed to but wiring is all inside the frame and looks like mice have eaten most of it up, so instead of messin with that and still have the battery problem I want to go gas power.

Sonny you only need the amount of HP that the speed of the cylinder vs.pump GPM requires..if you have a dump trailer then the cylinder speed really doesnt have to be that fast..do you already have the 8hp engine and are designing in reverse? I think the cheapest way would be a 11 or 16gpm splitter pump,it would give you fast dump speed with light brush or light material, but would have the pump kickdown for heavier material dumping at slow speed where you need hoist power..the 11gpm pumps are everywhere for about $100..even a 5hp engine will push a 11gpm 2-stage pump.

I have the engine, an old pump from a combine that I used for many years on our log-splitter, the control valve, and the res. for it. Kinda thinkin since this was also a 2-way system it might work. I haul anywhere from a few hundred pounds to 5 or 6 tons on the trailer.----at times if loaded too much on front, I use long farm jack or a loader to help start the lift, so that part is no problem.---I always load it center or a bit tail heavy if heavy stuff,---gravel, wet manure, etc. --- After I got the feel of loading it, havent had a lift problem!.
The pump dont have to be fast,--just enough power to lift the bed. This electric pump is quite small and VERY slow---thats what kills the battery all the time.

I guess you could always just belt drive the pump and slow the pump down to match your HP of the engine you're gonna use with different size pulleys.

Thinkin of belt/pulley drive to start with since my pump turns the wrong way for direct connect. Lift speed dont need to be fast --- just get the bed up and back down! ---- got caught too many times with bed halfway down and battery dies----so trip home with bed part way up--- not something I want to do anymore.
I was thinking since the belt drive worked on the splitter with a 4" x 24" cylinder and moved fast, it should work on the trailers twin cyl. setup. I think they are 3 or 3.5 inch dia. on it.

I run the pump on the Jake (Mini hoe) with a belt.. works fine. I did have to put a idler in on the slack side to keep the belt from slipping tho. The dump kit I have in my pickup is a battery pig too. I leave the engine running when I use it. self powered system on the trailer is a good idea. can haul it with ANYTHING and still be able to run it.