Adding a pony motor to a M936

[goldneagle]

Here is another possible source. If you can get the power unit from a all-terrain scissors lift or boom lift it should be able to handle your hydraulic needs. The engine is small footprint and some are gasoline/LP combo units.

 

[Csm Davis]

Okay let's stop guessing. I know most of the powered loaders around here use a 4 cylinder so that will get us in the ballpark I know the mep002a is used as a APU on some of the military equipment. Maybe a MEP003A would be a good choice, it could be mounted in place of the spare and part of the tool box. It should run a nice sized 3 phase motor or Welder and why would you need both at once?

 

[jesusgatos]

Yeah Josh, I've still got that M88 APU. Also have a Kubota V2203 and am not sure which one I'm going to use to make a skid-mounted power supply unit for a mobile workshop. Been collecting parts for a while and so far I've got a really nice twin screw air compressor and complete generator setup from an M1031. Want to add hydraulics too, and looks like all that stuff would be a lot easier to adapt to the Kubota engine. Will end up using that M88 APU for something though, it's such a nice little package.

 

[tobyS]

Actually CMDavis, I have a hydraulic crane myself with 51' stick that would have only slightly less volume or pressure (it doesn't have as large of winch). It has a 1/2" ID main pressure hose that I know well, having to put seals in virtually every component, including an 8 passage swivel. I operate at 1500 and have a foot petal throttle control, pto driven from a 390. So it's not entirely a guess. Perhaps you dispute the math or think I was just guessing there too.

I hold saw machinery and equipment in place with the crane and weld it...many times. Grain legs have to be held as lots of other heavy parts that are being assembled.

Did you ever own a shop smith with the attachments to make it a rip, router, bandsaw and other multi-function use. Well it was a pain in the ass to change and just as expensive as individual tools. Same principle.

 

[Munchies]

Found it.
This is the M88a2 (hatz version) APU pump.
Like the M88 crewman said it wont run some stuff. But I think it will do a wrecker fine. If we can get the flow and PSI of the wrecker pump then all will be revealed.
http://catalog.hydraulic-controls.com/item/gear-pumps-and-motors/bosch-f-series-gear-pumps/item-4897
http://recoveryvehicles.tpub.com/TM-9-2350-292-24P/css/TM-9-2350-292-24P_979.htm
http://recoveryvehicles.tpub.com/TM-9-2350-292-24P/css/TM-9-2350-292-24P_980.htm

 

[goldneagle]

I had an Air Force Air compressor MC-2A that used a HATZ air cooled engine to power a rotary air compressor. The motor is small in size so it would be good fit. Here ia a picture of the motor inside the compressor trailer:

 

[tobyS]

Munchies, Look at the pump specs for the pump you reference. It states just under 4 gpm @1800 rpm. Even if you were to turn it at 3500 (screaming for a pump), it would be under 8 gpm and forget it in winter, cold fluid will cavitate.

I spent some time in the TM's but cannot find any reference to size of ports, flow or pressure.

I'll stay with estimating flow in the 15-25 gpm area for normal operation speeds (based on what my crane of similar size needs) and especially with coordinated use of 2 functions simultaneously. The pump you referenced would then (at 1800 rpm) take from 4 to 6+ times as long to do the same movement or simply stall the engine or electric motor.

A simple measurement of the tube ID on the pressure side on the pump is enough to give accurate flow (assuming the OEM design is laminar flow as it should be) and then with pressure one determines HP at the pump by the formula (Q x P)/1714...and that is NOT a guess.

 

[Csm Davis]

Actually CMDavis, I have a hydraulic crane myself with 51' stick that would have only slightly less volume or pressure (it doesn't have as large of winch). It has a 1/2" ID main pressure hose that I know well, having to put seals in virtually every component, including an 8 passage swivel. I operate at 1500 and have a foot petal throttle control, pto driven from a 390. So it's not entirely a guess. Perhaps you dispute the math or think I was just guessing there too.

I didn't say your math is wrong and didn't wasn't pointing my comments at just you.

I hold saw machinery and equipment in place with the crane and weld it...many times. Grain legs have to be held as lots of other heavy parts that are being assembled.

The crane will not be using any power to hold something while you weld.

Did you ever own a shop smith with the attachments to make it a rip, router, bandsaw and other multi-function use. Well it was a pain in the ass to change and just as expensive as individual tools. Same principle.

And no never owned a shop smith but you could use an electrical motor to power the hydraulic systems and use a Welder off of the same APU at different times and have no problems and as far as switching from one to the other would be as easy as, well, flipping a switch.

I design hydraulic systems for sawmills and integrate Siemens programmable controls on them, achieving repeatable blade placement within .002" (electric over hydraulic).

I have at least 4 hydraulic pumps on hand that would work and know how to use them. Do you think I'm qualified to make a "guess"? Apparently not.

But thanks for repeating that a 3 or 4 cylinder would work, I would not have ever guessed it!

Don't get so twisted over this crap it will drive you crazy if you are to sensitive about Internet post they are not all about you.

 

[Csm Davis]

TobyS this is for you the lines on most of the wrecker are 1&1/4 to 1&1/2 in size and that may be underestimated but can get you an accurate size tomorrow as I will be working on one of my wreckers and might even be able to get what pressure they are set for from the guys that actually set them.

 

[tobyS]

Ok Jeff, thanks for putting the size up. It's something to work from until size and pressure is verified. I'll use 1" ID for now.

If the ID is about 1", from the table I referenced above, that corresponds to around 60 gpm of flow (at 25 fps). It's capable of a LOT more flow than my crane.

Staying with 1500 # (for now) and putting them into the HP equation (60 x 1500)/1714 = 52.50 hp.

If one can carry a generator (or welder) and electric motor anywhere near that hp, then it's more welder than I can envision (and that is without conversion efficiency loss). It's not going to work with a Trailblazer at 16 hp (or if it does, will be excruciatingly slow).

If the operating pressure is 1000#, it is still 35 horsepower (with no conversion efficiency loss). In an engine to generator to electric motor to hydraulic pump setup, I would put conversion loss at 50% or so, thus requiring around 100 hp to begin with.

His 6 cylinder engine above, directly driving the hydraulic pump, looks better with that much flow. Also, in that case, he could use the pump from the truck and just need flange mount adapter and a flex-plate and longer hoses.

When you verify the size and pressure, if possible, get the ID of the pressure line (hose fitting or tube).

I came close to buying one and making a three stage boom, so have had a lot of time to ponder this idea of alternate power. I was eyeing the 28 hp apu...which now seems on the small side.

 

[Vintage iron]

Toby thanks for all your help and talking it over with me on the phone. I will work on getting the output hose ID for you. Once we all can start with the facts, then we can develope a proper plan. I have a few options on power plants. I have the engine I posted earlier and an old 4000 LB propane fork lift too. The propane fork lift would be whisper quite. That would be nice

 

[tobyS]

Thanks Matt. It would be a real pain to go to the trouble of putting something together and watch it move like a snail.

Yea, the fork truck engine sounds good too. Most are 4 cyl in that size. Whatever you do, you might want to consider a foot throttle, rather than constant speed governor.

GL may have permanently changed my plan of getting and modifying a wrecker... good luck with the one you are getting.

 

[Csm Davis]

TobyS I think your 50 hp figure will be about right which is why I suggested the MEP003A if I remember right that's about how much that engine puts out. And the pump on the 936 is on the truck but the pump on a 816 is on the crane.

 

[tobyS]

The generator has 6.7 hp per 5 kw (converting KW to HP) so a 10 kw would have about 13.4. That sounds a bit small if the 50 hp is correct.

Sorry Jeff...I didn't mean to get so testy... but having my GL post closed with no discussion was like saying I cannot talk about an issue very close to me and my plans. I have bought 7 and sold 5, making it a fun part of my small business....which future sales now appear to be at the end.

I'm glad to have a rebuild 925 and nice 817 dump on hand, but was close to selling them, thinking I would get others. It was a shock to be told I can't even talk about the GL issue on SS.

 

[Csm Davis]

Yeah I think you generator figures are for the civilian gensets, and yes they get testy over GL.

 

[Munchies]

003A is 16HP at 1800 and 18HP at 2000 RPM Conservatively. I would hate to use an engine much bigger than it. A modern direct injection diesl, like a reefer engine might be a better choice. better HP/weight ratio.

I guess my APU idea was more of an auxiliary functions, booming around, sucking in cable etc not picking up trucks with the boom and needing max power situations.

 

[Csm Davis]

So Munchies I could replace the MEP003A motor with a Honda 20 hp and loose like 300 lbs?

 

[Munchies]

For light loads. The heavy rotating mass and low end torque at 1800RPM makes a killer combination. Look at the mep-803a vs mep-003a conversations going on now. Smaller engine with better hp/weight, but less lugging ability and less torque. 003a can take a bigger overload than an 803A. REALLY hard to beat mep-003A's. Yours looks good besides some tin/sheet metal carnage

I heard the same in that 6BT deuce repower thread. Basically yah its got more power, but the rotating mass makes a big difference in some situations.

 

[Csm Davis]

Oh by the way TobyS the pressure is set at 1350 lbs and it's a 2" line. Pressure I believe is fact because someone looked it up the two inch is off the top of a different person's head.

 

[tobyS]

Jeff, the 1350# makes sense but 2" is probably the suction, not pressure side.

I went back through several KW to HP conversions and still get 13.4 HP for 10kw. Since they would rate the gen on output, the numbers by Munchies of 16 and 18 look correct for engine HP.

Keeping with the earlier size of around 1" ID (60 gpm) at 1350# the HP is 47.25 for normal speed and power.

With a properly sized pump the 003 engine will work at about 1/3 of the normal system speed (flow is speed) but it can have full lifting capacity (pressure). With the pump too large for the engine (displacement/flow), it will simply stall it if you push the control valve too far... but have slightly more speed getting there. It will be rather tricky to operate but can be done.

Personally I would be looking for a 30kw (or 45) gen set that one can salvage the engine...or the fork truck Matt mentioned, but I would stay away from high rpm auto engines because of cavitation in cold weather (Maine).

Once an engine is chosen and HP available is known (at a given rpm), then we can calculate the displacement of the pump. Even a 5 hp Briggs can move things and give full lifting power if the pump is correctly sized to the engine...but it will move like a snail.

I think we are closing in on around 50 hp for full speed and lift power if the OEM pump is used (but of course the pressure side flow is still an issue because 2" would be a couple hundred gals/minute and quite unlikely).