Fifth wheel question

[cranetruck]

Among other things, I'm now working on the 5th wheel installation on the XM757. The set I have came from an M52A2 and the approach ramp is shorter than the one normally used on my truck.

Question, do the "tips" of the 5th wheel have to be supported for any reason? They rested on the cross member at the end of the ramp on the M52, but for proper location of the "wheel", they are not supported as shown in the image below. Do I need to add a support?

Also, is there a fixed height relationship between the max height of the ramp and the height of the 5th wheel when it is horizontal?


Thanks.

 

[cranetruck]

Spent a little time on the 5th wheel again today. Got the 1x3 flat stock spacers in place with "cavities" for the rivets on the frame.
Positioned it for marking of more holes to be drilled.
Ran the deuce (crane) for the first time in a while to help with the lifting.

 

[gimpyrobb]

Looks real good Bjorn.

 

[alphadeltaromeo]

I'd second that gimpy...you're doing a great job. I am rather envious of that crane I must say. It sure does make doing heavy work much more bearable.

 

[cranetruck]

Here is a different view of the operation.
The second image shows how the 5th wheel was removed from the M52A2. The spacer was riveted to the flange. The new spacer will be attached with bolts to the brackets along the side on the xm757, not exactly the way it was done on the original, but untill I find the right spacer and approach ramp, it will do.

 

[Recovry4x4]

I am rather envious of that crane I must say. It sure does make doing heavy work much more bearable.

You have no idea how useful that crane is. Bjorn has stopped by twice with the cranetruck. Both times it has amazed me with what it can do. His last visit he used it to install the engine in my wrecker, remove the bed from the pipeline truck and then flip it over for loading. It's a huge robotic arm. You never lift a spare when you have that thing with you. You don't jack things up either.

 

[ARMYMAN30YearsPlus]

Bjorn:
The ramps are there to keep the tips up so the kingpin of the trailer does not wind up riding up one of the sides of the fifth wheel. They also stabilize a tactical fifth wheel since ours rock both port and starboard and fore and aft. Careful backing almost always results in a good hook up so they can be lived without see my dolly conversion I did not make ramps for it and it works fine. Is that M52 being used for parts?

 

[ken]

I agree with dave. The kingpin could easily run up on top instead of sliding into the jaws.
Also if the landing gear has sank into the mud for some reason then the ramps closer to the tips will help lift the trailor should you have to ram it up to couple them. A M127 will only rise to about 56 inches on level ground without the wood pads under the landing gear. And a 52's wheel height is 56 11/16. So it makes life alot easier to use the pads. How high will the fifth wheel be when its moounted?

 

[cranetruck]

David, the M52 was cut up further by the new owner, who bought it for parts. He is in Oklahoma.
The 5th wheel has wedges to keep it from rocking from side to side when on hard level surface. Of road, the wedges are pulled out to allow sideways movement.

Ken, the height of the 5th wheel on the 757 is 55-1/4 according to the drawings. Mine will be about 53 inches mounted as shown in the images above.

 

[ken]

At 53 inches that will keep the trailor about level. I noticed in the pic from the pass side that the folcrum on the fith wheel was just forward of the folcrum for the springs. How far forward are you planning on mounting the wheel? My 52 is pretty much dead center.
Do you know how far it is between the centerline of the front axle and the center of the rear springs? I was wondering how much longer/shorter it is than a 52.

 

[cranetruck]

Ken, these drawings should give you most of the dimensions. The 5th wheel on the 757 will be 4-3/16 inches forward of the center of the bogie. It's not shown in this particular drawing, but it's the same as the M52.

The axles in each bogie are 58 inches apart and spacing from the rear front axle to front rear axle is 90 inches (ctr to ctr).

 

[cranetruck]

Metal cutting the hard way.

 

[ken]

Looks like it's almost the same size as a 52. What TM did you find the drawings in?

 

[cranetruck]

Tm 43-0001-31 has all the drawings. The detailed M52 one is courtesy David Doyle and is in pdf format.

 

[clinto]

Very nice Bjorn. Nice workmanship and well thought out, as always.

 

[cranetruck]

Tacked the brackets in place. The pieces can now be brought to a shop for expert welding.

 

[No.2Diesel]

Yamma Hamma! You need a DoAll band saw Nice substitute method though I like the serpentine leafsprings.

 

[gimpyrobb]

Bjorn, not to side track too much, what prep do you do before priming?

 

[cranetruck]

Nothing fancy Gimpy, the original paint is still good, so I scrape, sand, wash and wirebrush the previous owner's poor paint job off and prime it with good old Rustoleum "rusty metal" primer. I take pictures as markings and numbers apperar (see image below).
Oily parts get soap and water and degreaser first. Bare aluminum gets yellow zink chromate primer and then Rustoleum for a uniform foundation for the Aervoe 997B (24084).
I wait at least 3 days for the primer to cure before applying the semi gloss OD.
I'm aware of the potential problems with Aervoe, but next time painting will be a breeze in comparison.

 

[redass73]

Looks good, bjorn.