Testing 5 ton Sprag?

[cbvet]

Got a hill on my property we call Hummer Hill. (Now come on you guys, this is a military vehicle website. I'm talking about the AM General Hummer.)
We named the hill, because guys from the Guard have brought Hummers over from time to time to see if they could climb the hill. They go right up with no slippage at all.
I just tried to take the 5 ton up the hill, & didn't make it.
I don't think the front drive was working, but I'm not 100 percent on that.
Truck has the 1400 x 20 super singles.
What's the easiest way to test the Sprag on this?
And what are the "lockers" I've read about?
Well, it's Veterans Day. I think I'll go have a beer & contemplate Hummers.
Eric
CBVET

 

[rmgill]

A little bit of weight in the back might have helped. Couple thousand pounds.

 

[wdbtchr]

Want to test it jack up a front wheel(make sure you have airpressure if it's an air shift), put it in first and try to turn the wheel. It should turn in one direction but not the other, then put it in reverse and it should be just the opposite. Mine worked in reverse, but not forward untill I changed the air valve on the transmission.

 

[country]

eric

your run up the hill is the test

Have someone stand next to the truck while you are driving up the hill and see if the front tires are spinning

if not, it is NOt working

Dave

 

[cbvet]

It's a 5 ton M813A1, therefore Sprag. There is evidence of the rear wheels slipping on the wet foliage, but not the front.
Is there an adjustment I should be checking?
Thanks,
Eric
CBVET

 

[73m819]

the rear may slip a little and not the front, if the rear does not slip a bit the front wont lock in and pull, also if you have the air switch installed per the mwo to shut off the air to the xcase, there by putting the sprag in neutral the front will not pull if the air is turned off

 

[cbvet]

"If you have the air switch installed per the mwo to shut off the air to the xcase"
I have no idea what this is or where it would be located. I thought that with a sprag, there is no "air shift".
Please explain.
Eric
CBVET

 

[73m819]

the 5t has a air shift piston in the xcase to shift the sprag from forward to reverse, this get air from a air switch on the trans, this only works in first or reverse, this is why you should always start in first after going in reverse, thw mwo uses a flip valve to shut the air off to the trans air air switch, this flip valel is the same one used for the air shift deuce airshift, not all 5ts have this mwo, in fact most that i have seen dont

 

[cbvet]

No, I don't have a switch.
But now I know what the air-venting noise I hear is.
So is having an observer while climbing a steep slippery hill the only way to test the sprag?
Eric
CBVET

 

[73m819]

the rear has to over run the front inorder to engage the sprag, this is the case in both forward and reverse

 

[cbvet]

So you're saying maybe I didn't let it slip "enough" for the front to engage?
Eric
CBVET

 

[73m819]

does not take a lot of slip

 

[m139h2otruck]

I would do the test wdbtchr suggested. Did this on ours to check operation when we were getting noise out of it. Since flushing and refilling with new oil, no problems all summer at the job sites, full of 4000 gallons of water in and over sand and gravel.