hydraulic latch release

[Lmtv772]

I noticed on several LMTV, that the cab would not unlatch when raised. I've seen that happen on 3 LMTV. They said the part is not serviceable , but I am not so sure about that that. Has anyone attempted to free the hydraulic pin? I think that is what prevents the latch from releasing.

 

[DSD277]

Not true. I rebuilt mine years ago. Just a matter of getting them off ,remove the end cap, clean them up and replace seals. I don't remember the size o ring, just grabbed what I had in my collection of o rings.

 

[Lmtv772]

DSD277 ,
Did yours leak or failed to unlatch the cab?
How did you manage to get yours off? i think, if I can get a screw driver in the actuator I can maybe push it back and release the latch. Don't know , the next option would be to get those bolt off that hold the pin to the cabin.
But I'd prefer to get the latch unlatched.

 

[DSD277]

The latch had frozen and the strike had been removed from the cab by some one before I bought the truck. It has been years now, but iirc, I had removed the latch assembly and removed the end cap (there is a return spring in there, again iirc), soaked the piston until it could be pulled from the assembly, the internals cleaned and gunk removed. It is nothing more than a simple slave cylinder that a rod lock the catch and and fluid pressure pulls it back to unlock through catch. I might have written it up in my build thread. Like most everything else other than the cab sheetmetal, the catch assembly is commercially available. I had located it, but never bought one, due to the lack of need.

 

[tennmogger]

The little cy!inder is easy to service right on the truck and with the cab down and locked. In fact, that seems to be the safe way to do it. The big hex on the cap of the little cylinder is 1-1\2 inch I recall. Just unscrew it, remove the cap, use the shaft end to wiggle the piston to pull it out. Use care to not damage the shaft end because an oil wiper runs on it.

Once the piston is out, find appropriate o-ring and replace. I used some assembly paste when reassembling. The wiper on the shaft can also be replaced but do not make it a complete seal or pressure will trap between the piston and the oil wiper and the piston will be locked in. Yeah, I found out the hard way.

Word of warning, do not partially jack up the cab then remove the lock cylinder. Hydraulic fluid will dump and cab will come down. The lock cylinder and jack pistons are on the same circuit.

 

[Lmtv772]

is there a lot of fluid that will leak out when I take the cap off? great info on the size, I really appreciate that, Sir .

 

[NDT]

Try this post: http://www.steelsoldiers.com/showth...M-not-covered-in-TMs&highlight=fmtv+cab+latch

 

[tennmogger]

Excellent NDT, thanks. I had not seen that thread either.

 

[bikeracer917]

Does anyone have any part numbers to the o-rings in the latch? When I try to lift the cab fluid leaks out right where the little red button is?

 

[TNriverjet]

Bikeracer, I think the info you need is referenced in the thread linked in post #7 above.