Adding a pony motor to a M936

[Munchies]

I wonder what that little pump makes for GPM at half the PSI? I am sure there is a calculator for it, but just tossing ideas here.

Your looking at a mep-004a engine for that power level. It could work if you were to find a cheap 400hz version, scrap/part out everything but the engine and some control circuitry.
All the old meps are getting very thin in numbers this year. Going the way of the deuce.

 

[Csm Davis]

Okay rereading over the thread ferro listed 18 hp at 1800 rpm as factory recommended for the pump on a 936 and I know 1350 psi so I am going to go out on a limb and said a MEP003A will work and now to figure out how to attach it to the system. Munchies how about it any way to attach a shaft on one or both ends of a complete genset? I want to add this as a mod for my wrecker.

 

[tobyS]

Munchies, If you don't plan on full pressure, it will stall the engine any time you have a load. What you can vary is the volume (flow). Here is an example using the 003 engine.

Jeff, okay, say you use the 003 engine and have 16 hp @ 1800. Reversing the formula 16 = (Q x P)/ 1714...or... 16 x 1714 = Q x 1350 thus Q = 20.31 Gals. So the pump must pump 20 gals/minute turning 1800 rpm. There are 231 cubic inches per gallon. So 20 x 231 = 4620 cu. inch. Thus 4620 / 1800 = 2.57 cu inch/rev displacement hydraulic pump is needed for that engine. If I were being paid to design it, I would use 1500# and around a 2.3 cu.in/r pump.

If 60 gpm is near correct, the above engine/pump combo will move at 1/3 the normal speed and be capable of full lift.

 

[Vintage iron]

Once we figure out the proper motor size and if a propane forklift will do the job. I am think having a foot throttle would be great to help on cable in and booming up. Not sure how to make a foot throttle work if the pony motor is mounted on the truck bed? Would the motor need to be mounted on the rotator? It wouldn't be bad if the motor was quiet.

 

[Munchies]

If you want to do a mep-003a engine. I would get with billypop http://www.steelsoldiers.com/showthread.php?117754-New-Rebuilt-MEP-003-engines&highlight=mep+engine

If you want to run a pump off a complete generator...I guess it could be done, probably need to design a flange and shaft to mount on the blower end. I guess it could work.

I found a voltage regulator for my APU in germany, its on the way... Been meaning to fire it up for a long time. I need to go look up the HP rating on this thing..

 

[Munchies]

Also I am working on getting the tech specs of the 939 wrecker main pump. Drawings and specs are available but only to DLA account holders.

 

[Csm Davis]

Looked at pressure line on wrecker today marked 1 and 1/4" so that and 1350 equals what TobyS?

 

[tobyS]

Jeff, if the hose is marked 1 1/4" then the inside diameter is that size. That is capable of a LOT of flow and it will really help if munchies gets the pump number to verify it. What we CAN vary is the speed (flow) but we have to always make enough pressure. The design of any APU must make the pump so it will not stall the engine (thus use 1500 not operating pres. 1350 for design).

Here is a chart with hose flows and instead of using 25 feet/second I will drop back to 15 fps (smaller hose is usually moving faster).

http://www.ryco.com.au/index.php?id=196

If a 1.25" is moving at 25 fps then the flow by that chart is 90+ gals/minute.
If it is moving at 15 fps then the flow is 60 gpm.

The last series of calculations (above post) was specific to the 16 horsepower engine and the 1350#. Nothing changes from the prior calculation, using 1500# still gives a pump that is about 2.3 cubic inch per revolution for the 16 hp engine and it is capable of pumping around (just under) 20 gpm.

Now if the OEM pump pumps 60 and our APU can pump 20, it will move at 1/3 speed (33%) , but if the OEM pump is pumping 90 then it will move at 2/9 or about 22% of the normal maximum speed.

Now lets go back and figure how much horsepower the OEM is using at the higher flow, for comparison. Using the formula (Q x P) / 1714 = HP I plug in our values:

(90 x 1350) / 1714 = 71 hp
(90 x 1500) / 1714 = 79

(60 x 1350) / 1714 = 47
(60 x 1500) / 1714 = 53

So we have developed a range using 60 gpm and 90 gpm for the 1350 operating pressure and the 1500 design pressure.... resulting in from 47 to 79 HP.

I would think one hardly ever uses the full maximum capacity of this machine of either the speed or the lift capacity.

We need the OEM pump data to fine tune our numbers, since it is a large amount of flow...but the engine Matt (VI) pictured above is looking better all the time for a full capacity APU, especially if one wants to use the OEM pump and just mount it on the engine, taking it off the transfer case.

We can figure any engine hp and pump combination since we know how much pressure we have to make... and then calculate the speed in relation to the OEM speed (once we verify the OEM pump info.). Note all calculations are based on 1800 rpm.

What I can tell you for sure is that if you use the 16 hp engine at 1800, you need a pump that is 2.3 cu.in/r size and that it will move from 22 to 33% of it's normal speed.

Does this make sense to you?

 

[Vintage iron]

Wow! That is a lot of info Toby . Thank you for taking the time to share it with us.

 

[Vintage iron]

Well, I am pretty close to adding a pony motor to my Weecker. I total rebuilt the engine in my 1984 Honda a Goldwing last year and after it was complete I was almost driven off the road twice. People just don't pay attention around here. So the motor will power the rear PTO on my wrecker instead

 

[tobyS]

I had a similar experience a long time ago on a 305 Honda. A person pulled out in front of me from a Wendys and I had to take a route through their front yard area and nearly went into the greenhouse seating. Karma must have been good that day as no damage was done. I love bikes but know the danger.

That sounds like a good combination and I hope you will post some pictures. My guess is third or fourth gear will be the sweet spot and 5 the might be a bit high. But that's the great thing about having a tranny, you can find whatever works for you for speed vs power. Even first or second gear will get your engine swap done, since speed is really not much of an issue. You sure will save on fuel.

Off topic...I have hauled 54 loads of construction debris with my M817 in the last 5 days...so know the 250 can use some serious fuel. About 15 more to go.

 

[Vintage iron]

I would like to put the motor on the rotator, so I can run the throttle while hoisting, just not sure if I can back feed the fluid to run the rear winch and I still need to get fluid to the front winch.

 

[tobyS]

Look for a check valve... that would probably be the only reason you could not back-feed. It would have an arrow on the body indicating direction. Or if you can locate a hydraulic diagram, send it and I'll tell you for sure.

Seals and hose don't care about direction and I think their control is separate from the cranes controls. It should work but plugging the line would get your crane operational.

I know you want to keep cost down by using the OEM pump, but a second pump might be a good answer, even if it is small. Yes, throttle is important but you could use electric solenoids. I did that on my sawmill that was all hydraulic.

 

[Vintage iron]

Thanks Toby. I do remember see about the check valves. I was under my M936 the other day, I was thinking how to mount the pony motor. Mounting the pony motor and pump on the rotator will make things so much easier to work on. I want to keep this project simple and functional.

 

[Csm Davis]

If you are going to use the gold wing motor I would mount it underneath the bed and keep the hydraulic systems as is just move the pump. But if you want to mount it and the motor on the rotating boom you can just back feed through the stock setup just use the pressure line that feed the boom to go down and feed the winches. And yes I would feed both winches the two pumps are stupid.

 

[Csm Davis]

Also I am working on a powered winch that is using a 3.3 cummins and it is a really nice little power pack ant has 60 hp , I may be way off but if this little engine is putting out that much hp I would think that the mep would be in the same range and am willing to bet my money on it. I am going to be looking to mount a MEP003A in my wrecker probably in the passenger side of my toolbox area.