Hi, I have a 1986 Ford Telsta Bucket Truck. It's my newest project to get up and running for doing work around the property. It came with an Onan 4.0BFA genset that had a PTO driven hydraulic pump on it top drive all the hydraulics on the truck. Right now I'm rebuilding the onan, so I came up with a way to move and test the hydraulics in the mean time. Since the pump has a lovejoy coupler on it, I welded together a mating piece that I could insert into a corded hand-held drill. It's a little slow, but it actually works really well driving the pump so I can move all the hydraulics (it's a 2 person job). So with the corded drill in mind, I was thinking that instead of worrying too much about the generator, that I could just put a heavier electric motor on the truck and just use that to continue to drive the hydraulics. Since I won't be much farther than a 120vac outlet, this could actually work, since the rest of the actuators for the hydraulics and such are run off of the 12v system in the truck. I was looking at using a 3/4 hp continuous duty 3600 RMP motor to drive the pump, and I was wondering if that was too high of an RPM, as I believe the genset runs at 1800 RPM. In the specs about the hydraulics, it doesn't list an RPM, but it says 1.6 gpm @2400psi max, and 1200psi operating pressure. So with my calculations, it needs more like a 1-1/2 HP motor, but I wasn't sure if I could get away with what I was talking about using above. Thanks for any input!
Yes, I'd say that's too fast for most pumps. Also the 3,600 motor also will have half the torque of the 1,800 of the same HP. Since you're already at less than half the theoretical HP of the motor I'd think it would stall easily. Also if you have electric solenoid controlled hydraulics (as opposed to hydraulic valves in the bucket), I wouldn't want the functions to move any faster than they did originally
You can get a electric motor to ron at 1740 rpm I believe,
I know I could theoretically limit the voltage into the motor to get a slower speed, but at the expense of torque. I guess from here the two best options are to 1) Find another motor more suitable or 2) put a 2:1 gear reduction on the motor, slowing it down, but upping the torque.
We are talking about an AC motor here right, plugged into 120? DC motors use voltage control but that's way over what we're talking about here. Typical capacitor start electric motors are mostly 1,800 rpm (nominal, 60hz American), 3,600 are less common. If you could find one, an old repulsion start motor would work great, they have excellent torque and tolerate low voltage well (for a few too many extension cords). "continuous duty" sounds suspicious, a typical motor will have a "service factor", SF, listed on the rating plate, 1.15 is common, which means 15% more than continuous duty.
Hi, Yes, I'm talking about 120v AC 60hz. The motor I was originally speaking of was off of our old pool pump. It's about 11 amps, and 3,600 RPM. 3/4 Horsepower again. On the plate of the motor it said "continuous duty", but it may have listed a S.F. as well, I'd have to look again. Either way, I know the 3,600 RPM is a deal breaker. I do have other motors from an old belt driven craftsman lathe that is 1800 RPM with capacitor start, but I believe it's only 1/2 or 1/3 HP. I found a 120vac 1.5 HP 1800 RPM motor on ebay earlier, I just might have to pick that one up and give it a shot. Seemed like a pretty good match, with capacitor start and run too.
Check With Hydraulic Specialist I would have to say I agree you definitely need a less powerful motor. I think it might be best to call a professional like http://www.beilerhydraulics.com/ . They specialize and things like these were most of us are just relying on things that we tried and tested. Does not necessarily mean we are less competent but sometimes our advice is more theory than fact. Checking with those guys before making any major adjustments can help you prevent any major problems in the future.
I actually ended up getting the generator working without further issue, so that solved my initial problem. However, in the process of going over everything else, I discovered that the 12vdc emergency pump motor was bad. I have since detached the 12vdc motor from the pump and have set it up to use my original drill concept. So now I have a gas powered generator running the hydraulics, and if it cuts out, I can switch over to the drill-powered pump. It would appear that the emergency pump is by the same manufacturer, however it must be designed for way lower HP. When I used the drill on the main pump, they moved relatively quickly, but on this pump, it takes WAY longer to move the same distance. The drill doesn't torque as much running this other pump either. I would assume that I might be able to put a lower HP motor on it now, and stay around 1800 RPMs and be good at this point.
The emergency pump is designed to give you enough power from the battery to lower the basket to the ground once if the engine or main pump fails, so yeah it only pumps a little oil compared to the normal system.