Fmtv crane maintenance manual, hydraulics specs?

[tobyS]

It helps a great deal and it looks like other than the hydraulic power there's a Cannon plug with 12 volt power going to it.

I talked to a shop today and they recommended I set it up with the pto setup. He said he can convert it to a direct flange Mount or stick with the driveshaft depending on how much room is in there. The pump is going to be about 500 bucks I'm still going to look to see if I can find a military pump with the drive shaft

Don't overlook an important point...this system requires a variable displacement piston (or some vanes) pump, pressure compensated, and is not a positive displacement (gear) type pump. Unless that OEM pump comes from an FMTV or HEMTT, it ain't gonna work. I'll grab the pad and go take a photo of mine for the next post.

 

[tobyS]

Here is what I'm using. Caution when you get the pump that it's direction is correct. Oh yea...and mine is a lot less flow for smaller stuff...like my 2" cylinders that I have 25 of.

 

[8madjack]

According to the maintenance manual it's a single stage pump I think that's just an ordinary positive displacement pump and I got the impression from the hydraulic guy when I told him that that it was that simple.

 

[8madjack]

The manual does show that the 1084 has a single stage pump and there is a 3-stage pump on the Wrecker

 

[tobyS]

It helps a great deal and it looks like other than the hydraulic power there's a Cannon plug with 12 volt power going to it.

I talked to a shop today and they recommended I set it up with the pto setup. He said he can convert it to a direct flange Mount or stick with the driveshaft depending on how much room is in there. The pump is going to be about 500 bucks I'm still going to look to see if I can find a military pump with the drive shaft

I don't think you understand what I'm saying about the pump.

Yes the driveshaft has to be used because there is not room to flange mount a pump, but if you purchase a pump from a 5 ton 939 series, they are gear pumps...they won't work.

Tell your hydraulics man you need a pressure compensated piston or vane pump that does connect by driveshaft. The one in my picture is a small one. It has the same mount as a gear pump SAE A, B or C (picture is A). That particular pump will be flange mounted on my M35A3, splined input.

I would use the next size up for your application, mine in the photo for my A3 is about 8 gal/min..

My point is it must be pressure compensated variable flow, not fixed flow.

I'm not trying to sell a pump, but I do have one the size you need... a Rexroth, with a straight keyed shaft. I can get more info off it if you would like.

 

[tobyS]

Not having read the wrecker TM, my observations have been that they use gear pumps, off the tranny and the transfer case. They are positive displacement and not compatible with the valving of the crane that was made for LMTV and HEMTT, with pressure maintaining(compensating)(but 0-full) flow, set at 2500 or so (made for 3000 min). EDIT---man does that sound like garbled up pile of ...

I'm not really sure what you mean by "stages".

 

[8madjack]

The wrecker I was referring to is the lmtv Wrecker. So can a single stage pump be either positive displacement gear or variable flow vein or piston Style?

I did a lot of reading online and I was under the impression that a single stage was positive flow. I definitely don't want to get the wrong pump. We can talk via p.m. about your hydraulic pump. I was hoping to find the parts together almost like kit form, perhaps I'm being greedy

I think I bought my PTO from you if I remember correctly. As long as I get to set up I need to run to dump hoist and this crane I'm happy.

 

[snowtrac nome]

all those pumps are positive displacement the other option you might see is a centrifugal pump but those are for light liquids like fuel and water. I think what you are asking is do you need a fixed flow pump or variable swashplate pump which would give you a variable floe and pressure. My short answer for a crane or winch is a fixed flow pd pump is all you really need.

 

[tobyS]

Sure, you got the PTO from me and that is partly why I don't want to see you get the wrong pump. But I'm pretty much the same with all people here, will help when I can. My purchase of the winch unit and determination to make it work has a lot to do with working these issues out too.

Your use of the crane is crossing two different animals re the hydraulics. If you buy the pump from the FMTV it should be one that will work and have the capacity in flow. I thought you meant you would buy driveshaft and pump from an M939 series. Driveshaft....maybe... but you do not need a gear pump.

Here is how the piston pump works.

https://www.youtube.com/watch?v=2mh902AP7Yw

Check out this for the gear pump

/www.youtube.com/watch?v=c6gwU7IHtlo

 

[tobyS]

all those pumps are positive displacement the other option you might see is a centrifugal pump but those are for light liquids like fuel and water. I think what you are asking is do you need a fixed flow pump or variable swashplate pump which would give you a variable floe and pressure. My short answer for a crane or winch is a fixed flow pd pump is all you really need.

Fixed flow and variable flow are two entirely different animals. Fixed flow will not work because the valve pressure port is blocked when the valve spool is in the center position. No flow is allowed to pass. If you have a fixed flow (gear) pump, it simply stalls the engine or breaks.

If the valve had an open center then fluid could circulate and a gear pump would work...like the valve of a 939 series wrecker...that's open to tank in neutral.... and doesn't stop the flow. It's called "open center valve" on the 5 ton wrecker but NOT the LMTV.

Look at the valves and manifold...they look entirely different.

 

[Lukes_deuce]

Anything ever come of this? Is the grove crane closed or open center?

 

[8madjack]

It's on my "things to do" list, been busy with other stuff unfortunately.

I plan on studying the heck out of the TMs, or hopefully run into a guy who worked on these specifically before actually doing it.

 

[Lukes_deuce]

Did some digging and came up with the following info for the standard FMTV pump:

 

[Lukes_deuce]

Did some digging for the pump and came up with the following info.
Technical Data | NSN 4320-01-363-2294

Characteristic	Specifications
MAXIMUM DISCHARGE FLOW RATE	22.5 GALLONS PER MINUTE
DISCHARGE PRESSURE	2938.0 POUNDS PER SQUARE INCH GAGE
OPERATING SPEED AT RATED CAPACITY	2400.0 REVOLUTIONS PER MINUTE
MEDIA FOR WHICH DESIGNED	HYDROCARBON FUELS AND OILS
PUMPING ELEMENT OPERATING POSITION	HORIZONTAL
PUMP ROTATION DIRECTION	CLOCKWISE
ROTARY PUMP DESIGN	GEAR
OPERATION METHOD	POWERED
INTAKE CONNECTION QUANTITY	1
INTAKE CONNECTION TYPE	THREADED INTERNAL
INTAKE CONNECTION THREAD SIZE AND SERIES/TYPE DESIGNATOR	1.625-12 PTF-SAE SHORT
DISCHARGE CONNECTION QUANTITY	1
DISCHARGE CONNECTION TYPE	THREADED INTERNAL
DISCHARGE CONNECTION THREAD SIZE AND SERIES/TYPE DESIGNATOR	1.063-12 PTF-SAE SHORT
DRIVE CONNECTION TYPE	CLOSE COUPLED
DRIVE SHAFT TYPE	SPLINED, INVOLUTE EXTERNAL
DRIVE SHAFT LENGTH	32.0 MILLIMETERS NOMINAL
MOUNTING TYPE	FLANGE

 

[Lukes_deuce]

To me, since its a gear pump, that means its a constant flow, open centered system. I am not an expert in hydraulics. I have basic understandings due to my use of the systems on trucks and equipment but I could not differentiate between the system types without some more knowledge. Hopefully someone can chime in who knows more.

 

[8madjack]

That information makes sense based on what I read in the manual a while back , I'm going to have to go out of my way to get eyes on an actual truck, there is an Army Depot base here maybe I can go talk to those guys

Thanks for that research and sharing it here

 

[319cssb]

Does anyone know the AN fitting size for the m1084 grove MHC ? The hoses are 3/8”, but what size are the fittings?

 

[coachgeo]

is there only ONE model of pump installed on the Allison for the whole range of the MTV's and LMTV's? If so would that make it wayyyyyy over pumped for say winch trucks..... and about right for the trucks with cranes etc??

 

[8madjack]

Does anyone know the AN fitting size for the m1084 grove MHC ? The hoses are 3/8”, but what size are the fittings?

I can look at mine, I think the ones that connect to the truck are larger than that but between the sections I'm assuming is what you're talking about

 

[319cssb]

Yes sir