DIY 24v HPU?

erikg · Jun 7, 2012

Hi, all;

I have a question to ask, but some background first: I'm working on getting a simple Johnny-bucket style scoop on the front of my (modified) lawn tractor set up. I want long term to weld up a full FEL setup with a hydraulic pump run off the engine, but I need something working in the next month or so in order to do some landscaping.

I'm thinking I'll hang a couple of deep cycle batteries I happen to have off the back end and run a couple electric powered hydraulic pumps to run two cylinders, one for lift and one for tilt/dump.

I have a 12 volt HPU off of a pallet jack that works well, I was thinking I'd use it with a single acting cylinder for bucket lift.

I don't have a second power unit, and I wouldn't want to try running two cylinders off the little 12v hpu.

What I was thinking was that I could build an HPU using a 1 hp 24 volt electric motor I have and a suitable hydraulic pump. If I understand correctly I could dedicate it to running one cylinder and control it by reversing the motor and using appropriate check valves.

That way I could control lift and tilt with low voltage switches connected to 12/24v contactors. I'd have to run 1-2 hydraulic lines per cylinder from the hpus to the cylinders, but that's it... no valving or reservoir.

Would this work, and can anyone think of a better plan? I can afford to buy a hydraulic pump or two at the moment, and some hoses, but the cost of a full engine driven pump, valve, and reservoir set up is out of range right now. I have four 1 hp 24v motors, a 36 v 3 hp motor, and a 13 hp gas motor available, plus the little 12v hpu and its cylinder. I also have enough traction type deep cycle batteries to run the motors for a usable amount of time.

Thanks,
Erik

J_J · Jun 7, 2012

Your 13 HP engine can run a single stage 6.5 GPM pump. If you need 3000 psi, then the displacement on the pump would be .4 cu in.

You can run a two stage 22 GPM pump with that engine also. 7 GPM at high pressure and 22 GPM at low pressure.

erikg · Jun 7, 2012

If I did that, I'd guess I'd need to buy a valve and reservoir set up to control it?

As I understand it from other folks that have done a small FEL set up for their lawn tractors/garden tractors, it's unlikely I'll need more than about 1500 psi given the load I'll be handling.

I should maybe mention that the tractor itself has a 20 hp briggs engine, so long term I'd want to run off of that.

Erik

J_J · Jun 7, 2012

Can you add another pulley to engine shaft to drive a small hyd pump.

The steering and lift is controlled by a small 3 GPM 3000 psi pump. My pump is driven off the fan belt on my 4 cyl engine.

Gear Pumps 302-016 Detailed Information

oldnslo · Jun 7, 2012

Word of caution on some DC HPU's. They are intended for very intermittent duty. Some of them are only good for 3 minutes run time every 30 minutes.

What you would need for the single acting lift cylinders is a "lift, check, dump" circuit. Companies like Delta Power, Hydra-Force, etc make these.

You will need some way to charge the batteries since these units use lot' of amperage to run.

Roy

J_J · Jun 7, 2012

You might also get away with 12v linear motors. The small Struck dozer uses on on the front and the back to lift the implements.

erikg · Jun 13, 2012

J_J said:
You might also get away with 12v linear motors. The small Struck dozer uses on on the front and the back to lift the implements.

Thanks.. I thought about these, but the sizes I'd need (travel of 12 and 8 inches or so and force of 500-ish lbs) put purchasing new ones out of the picture. I do have a couple 24 volt units, but I'd need two batteries to power them plus a way to charge them.

I think what I'm going to do is buy a couple of small haldex-barnes 12v power units at a local surplus place. They're only rated for 10% duty, true, but for what I'm doing I am only going to run them maybe 15-20 seconds at a time every 3-5 min or so... that works out to about 6-7 min in an hour, which is about right.

One hpu for lift (about 12-18 inches travel) and one for bucket tilt (about 6-8 inches travel) both powered off an oversize battery charged by a spare car alternator I have. Total cost will be about $200 for everything except a few hoses, given that I already have the hydraulic cylinders. I think I'll mount the HPUs near the front of the tractor to keep the hoses short, and control things with a couple momentary toggle switches clamped to the steering wheel. I have some spare solenoids I can use if needs be for control.

I'll let you know how things go.

Erik

erikg · Jun 21, 2012

erikg said:
Total cost will be about $200 for everything except a few hoses, given that I already have the hydraulic cylinders.

Well, I was looking for a motor to convert a 110v hpu into a 12v unit, and I got lucky and ran across some surplus hydraulics. A Danfoss 1635 three spool valve that needs a cleaning, and a Delta Power D21M pump, both together for $120. I'm going to clean them up and I'm planning on using them with the cylinders I already have instead of the electric units.

So looks like I'm going to go the conventional way instead of HPU, assuming the surplus units work. I think I'll use the 12v power unit for a hoist or shop press.

From what I can tell from the specs on the pump, it's about a 5 gpm reversible unit at 2000 rpm. It has an extended shaft and includes an outboard bearing, which will save me installing a jack shaft. I'll run it off of a pulley from the tractor engine. The valve I'll use two spools for the bucket and one maybe for a three point hitch later on. It needs handles, but otherwise seems functional. I'll have to disassemble it and clean out some dirt because it wasn't capped for storage, unless there's a way to flush it with oil.

Onward and upward.

Erik