M931a1 crane and dump

[8madjack]

I have a 931a1 with a cut down dropside bed. I bought a grove material handling crane from an FMTV which I'll pick up next week. I also plan a dump conversion.

I have a PTO from a member here, still need the pump, drive shaft and brackets. I also need to figure if the hydraulic tank from a winch truck will be sufficient or if ill neeed a bigger tank. I understand that bigger is better if I have room.

I still have to source a tank and hoist as well. Ill post as I make progress and if anyone has input on tanks, aquiring parts, hydraulics or the project in general I'm all ears!

I'm currently looking at various dump bed threads.

 

[Jbulach]

Tank size depends on the hoist, if it uses double acting cylinder/s, you can get away with a smaller tank.


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[porkysplace]

Tank size depends on the hoist, if it uses double acting cylinder/s, you can get away with a smaller tank.


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The crane probably needs a bigger tank than the dump. You need to figure out the flow volume of each.

 

[8madjack]

Thanks for the replys, yes, I want a double acting cylinder so I can power the dump down also. I downloaded the book for the fmtv I'll see what volume that pump pushes.

 

[tobyS]

Sounds like a great project.

Figure the volume of the cylinders in cubic inches (pie R square x stroke in inches) / 231. I'd have at least 2x the total volume or more.

Do you have the crane winch already connected with hydraulic lines? I'm working on a Grove Crane winch and trying to understand how hydraulic pressure affects the brake unit. From what I can tell, there are three control ports on the brake, one that puts additional pressure in addition to the internal springs pushing the plates together (stopping rotation), one that acts on the piston to relieve the spring pressure (allowing rotation) and one that feeds the wet clutch packs with pressure which would also release the brake. All braking is one direction only with a one way clutch on the brake shaft...I'm assuming out.

Oh, and the crane winch is supposed to be full of hydraulic oil...count about 1.5 gallon. You can have a smaller tank, but don't forget to fill the winch first.

Having my winch out and completely apart, it's getting new o-rings....someone tried to use silicone to seal it and it made more problems than it solved.

Also...pay attention to your valves, especially the one for the crane. Is it open center and need a gear (constant displacement) pump or is it closed center where a variable volume, pressure compensated (piston usually) pump is needed? Don't mix....they won't match.

Edit...I thought you already had the crane. Upon re-reading, I see you are looking.

 

[8madjack]

I made the deal, picking up next week. The wich is attached and it was operational just prior to removal from the fmtv.

I read that the fmtv has a variable pump. Ill have to look into that. Thanks for the good info!

 

[8madjack]

I can take whatever pics you need when I pick it up.

 

[8madjack]

Well, I read through the FMTV -10 and the hydraulic tank capacity is 27 gal. The pump is listed as a single stage pump on the cargo truck, which is what this crane is from. I did a lot of inline searching and from what I gather the single stage pump is constant and not variable. Chime in if that assumption is wrong. I'm learnig as I go.

As a note, the wrecker version has a 3 stage pump.

 

[tobyS]

You need a picture of the top of one of the valves. The industrial valves have a flow diagram on top. If the pressure (P port) shows a -T, it is blocked. If it shows the P port connected to tank, then it's a positive displacement. A hydraulic schematic for the crane would help a lot. What you call 2 stage may be a main pump with a smaller control circuit pump mounted on the back. We could use a single pump and have a pressure reducing valve for the control. From what I read, that control PSI is 195. Wonder what the main pump max pressure is?

 

[8madjack]

I'm going to look through the maintenance manuals for the FMTV, the info we seek will be in there. The operator manual only refers to the single stage pump and tank capacity. I have all the manuals for my m939 and they have the detail so I'm sure the equivalent for the fmtv will do the same.

I'm also going to stop by a local hydraulic shop that's been recommended to me and talk with them about my needs.

This is typical when I started a new style project there's always familiarization and learning to be done.

 

[74M35A2]

Jealous. Crane wanted.....

 

[Derrickl112]

.

 

[tobyS]

Lowering the boom while having it straight with the truck might be hazardous to the back of the cab.

 

[8madjack]

Lowering the boom while having it straight with the truck might be hazardous to the back of the cab.

Then dont

Looks similar to one I got. I was originally looking at knuckle booms but the folding one will be really compact.

 

[74M35A2]

How heavy is that one? I just want a light and simple one to launch my SeaDoo. Don’t want to be carting around a ton of extra weight.

 

[8madjack]

Ots about 4,000 lbs. You need one like my home built bumper crane on my F250. I'll share a pic later.

 

[8madjack]

It's not done yet, but here ya go

 

[grendel]

Jealous. Crane wanted.....

BS, you could buy mine anytime.

 

[red]

How heavy is that one? I just want a light and simple one to launch my SeaDoo. Don’t want to be carting around a ton of extra weight.

Could build a bed winch/tail roller setup.

 

[74M35A2]

It is all about cool factor at the boat launch. Had to be hydraulic pick and drop, directly at the seawall.

Go OP! Post pics as you go so we can drool.