• Steel Soldiers now has a few new forums, read more about it at: New Munitions Forums!

  • Microsoft MSN, Live, Hotmail, Outlook email users may not be receiving emails. We are working to resolve this issue. Please add support@steelsoldiers.com to your trusted contacts.

 

FMTV Air Hydraulic Unit Repair

NDT

Well-known member
Steel Soldiers Supporter
10,106
5,706
113
Location
Camp Wood/LC, TX
This is the unit that provides the hydraulic power to raise the cab. Mine functioned (barely), but was slobbering hydraulic oil all over the place, and had to be refilled all the time. Today I tore into it. Sure enough, the shaft seal on the plunger was shot, allowing high pressure oil to enter the air chamber and be expelled through the air vent. After digging around in the TMs, turns out this power pack is made by respected hydraulic tool manufacturer SPX Fluid Power, and the packing is called a "U-cup" p/n 14121. For once the "off the shelf" aspect of the FMTV worked out here, and the pump is a part of SPX's line of portable power packs, and the part is available online from MROsupply.com and others.

After action report: Finally got the HPU working again. Mistakes made: Didn't mark the hoses, put them on backwards, wouldn't pump. Didn't seal the air line, some bug made it's nest deep down in the line, plugging it and making me think the HPU wasn't working. And the best of all, I put the U-cup in backwards, and it didn't seal, spraying oil everywhere again. You would think this was my first rodeo.
 

Attachments

Last edited:

gimpyrobb

dumpsterlandingfromorbit!
27,785
747
113
Location
Cincy Ohio
I have a couple things from SPX and have always gotten great info(even blueprints) form them when I emailed for information. As long as you include the serial number, they are a great source of information.
 

Oxyacetylene

Active member
Steel Soldiers Supporter
516
176
43
Location
Stoneville, NC
That is great info. I have been thinking, maybe we need to start a list of part numbers and sources for the various things on these trucks.
 

Duckworthe

Member
329
22
18
Location
San Diego, Ca
Thanks for the post and info. Mine was and still is having the same issue as yours. Mine does work manually though. I ordered the U-cup and installed that little sucker, (somewhat of a pain to get it down into place) and after going through the whole unit it still wont work except manually. Still wants to blow out the vent. Any ideas ,besides putting on a new unit. Everything inside was in perfect condition except that the U-cup was deteriorated. Thanks.
 

NDT

Well-known member
Steel Soldiers Supporter
10,106
5,706
113
Location
Camp Wood/LC, TX
Thanks for the post and info. Mine was and still is having the same issue as yours. Mine does work manually though. I ordered the U-cup and installed that little sucker, (somewhat of a pain to get it down into place) and after going through the whole unit it still wont work except manually. Still wants to blow out the vent. Any ideas ,besides putting on a new unit. Everything inside was in perfect condition except that the U-cup was deteriorated. Thanks.
Are you SURE you put the u cup in the right way. The open part of the u should face the hydraulic oil so the pressure expands it.
 

Duckworthe

Member
329
22
18
Location
San Diego, Ca
As per the drawings and talking to SPX, who by the way are great. The way it goes in is opposite the way that it seems it would. Basically the lip and goes into the housing first and you have to use a small screw driver to gently work the lip down into the bore. If you put it in backwards, it goes right in and yes it wont seal. Maybe I messed it up putting it in? It blows air out of the vent but no fluid, and it doesn't have the power to raise the cab.
 

NDT

Well-known member
Steel Soldiers Supporter
10,106
5,706
113
Location
Camp Wood/LC, TX
Did you possibly connect the hoses backwards? I did that and the pump runs, but of course no movement.
 

wehring

Active member
1,375
25
38
Location
Angleton, TX
Just rebuilt mine and it is leaking again after only a week. Would like to get some OEM replacement o-rings. Anyone have a source?

justin wehring
979 997 3112
 

Suprman

Well-known member
Supporting Vendor
6,832
645
113
Location
Stratford/Connecticut
The parts tm has the full breakdown of the unit. I am pretty sure you can order any part of it from an spx dealer. I have a few cores I want to rebuild as spares I wonder if a major rebuild kit is available.
Will
 

Duckworthe

Member
329
22
18
Location
San Diego, Ca
I contacted SPX and i believe they said they don't have a total kit for it. Because it was a special sized piston kit for this truck use. So they don't have a one source kit available. but can buy it piece by piece. I need to get back on mine soon. The camper build is taking my time right now. I will get some pics up soon. My truck is looking amazing and running like a top. just need to swap out the gears for the MRAP units.
 

Lmtv772

Banned
651
18
0
Location
Florida
So I've ordered the parts for $22 from the supplier mentioned by the OP. MROsupply.com is an absolute nightmare as far as their customer support is concerned. But I got my parts in the end. So it's not that bad. I'd suggest contacting SPX directly. Their part # is 14121 for the seal and the phone # is (815)873-3715
 
Last edited:

NDT

Well-known member
Steel Soldiers Supporter
10,106
5,706
113
Location
Camp Wood/LC, TX
Coincidence you punched up this thread lmtv772. I think these parts get drop shipped from SPX.

Guess what I had to disassemble the HPU for the nth time. I left the decontaminator bracket off when I repaired this thing and rainwater made it past the exhaust muffler and hydrolocked the air cylinder. It would not pump.
 
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website like our supporting vendors. Their ads help keep Steel Soldiers going. Please consider disabling your ad blockers for the site. Thanks!

I've Disabled AdBlock
No Thanks