Pintle Riser Plate Safety

[blybrook]

12/17/11

I have searched a few threads and don't see this subject really handled. And by this subject, I mean SAFE riser plate construction / pintle attachment. We've alluded to it in several threads, but I do not see where we really stepped up and discussed it directly. By this, I mean that there are several posts from members showing how they utilized additional steel or built their own riser plates to get the pintle hitch higher for the military trailers beyond typical stock plates for use behind civy vehicles. Should you go about enlarging your plate, please do it in a safe manner to ensure the safety of yourself and everyone around you when you have a trailer connected.

I was at Lowes today and noted that something didn't look right on one of the civy vehicles as I walked by. I stopped on my way out as it was still there, so I snapped a couple of photos of what this individual did to tow their trailer. I really wish I had more time to sit and wait for this individual to come out of the store so I could express concern over their connection technique. The first three photos are what the shopper did to get their pintle attached. There is NO way that this should be considered safe as the hitch can easily rotate under a higher load and fail. It is relying on bolt fatigue from what appeared to be grade 5 bolts in the bottom holes only. The top holes are dummy bolted to give the impression that it is properly connected from the rear.

The second three photos are what I did recently to get my pintle higher to tow a M101 level with my civy truck as the 4 bolt plate was not tall enough. The channel is C6x5.4 and has a higher rotational resistance than the original 4 bolt riser plate (1/2" A36 steel plate), so I know it won't fail. Minor grinding was required on the interior edge to get it to fit around the original receiver plate, about a 1/4" material total. I utilized grade 8 bolts and self-locking hardware for all connections, along with ensuring that there was a minimum of 2 threads exposed beyond the end of the nut. I also plan to add some 1/4" plate between the legs of the channel at the top to create a box section come spring when I can get to my steel scrap pile again. I have no worries that this riser could be utilized for a fully loaded M105 (other than no trailer brakes) as I have towed the M101 with 350 gallons of water (3100 lbs w/ tank) with no issue or signs of distress.

Please construct your risers safely if you go about it. Don't skimp just to get the trailer home, its just not worth it.

Sorry for the quality of the photos, they were taken with the cell phone camera.

 

[flyxpl]

Not good , if they did not have a locking pin on the reciever , I would have removed the unsafe assembly for them .

 

[blybrook]

I had considered pulling the assembly; but decided best not to as I have no real authority perform said action.

I will be keeping an eye out for this vehicle while around town and should I find it, I plan to have a discussion on towing safety with them (next time, I will do my best to find the time to wait).

 

[bjsmith]

heres one i made to pull m105 behind my pickup is a lil over kill but didnt want to take a chance its 4 peices of 2X2X1/4 angle bolted to each side of riser then plate welded so even if bolts fail it would still not come off. i have hauled the m105 with 3500 lbs of scrap metal once to scrap yard but other than that all hauled was trailer with smaller things in it but i no longer have it so its time to try to win another from gl

 

[harleyhouse]

I fabed my Pintle / Ball combo mount from 1/2" plate cut to the same size as the mounting base on the cast pintle. Then welded it to a piece of 2" heavy wall tube.
It has worked well for me.

 

[quickfarms]

one has to remeber that when you extend the height or drop of the hitch jou greatly reduce the capacity.

 

[Preacherboy]

Here is the one I built to get the needed 36" of height, but I will stress that I only use it to haul empty m105's.

I have hauled empty m101a2's with it as well, but I have no worries with them.

13 Mike observed the hitch in use after we hooked up a m105 and noticed some flex upon braking, but deemed it safe to haul an empty trailer as long as I gave myself plenty of stopping room. He is a steel expert and I accepted his advice and concern.

It is a 19 3/4" plate bolted to Harbor Freight's largest pintle plate, and it is all bolted together with grade 8 bolts and I welded on a piece of angle iron...which could be done a little bit better than it is I will admit.

This hitch has hauled m105's many hundreds of miles and m332's and m101's without incident.

 

[goldneagle]

Here is the one I built to get the needed 36" of height, but I will stress that I only use it to haul empty m105's.

I have hauled empty m101a2's with it as well, but I have no worries with them.

13 Mike observed the hitch in use after we hooked up a m105 and noticed some flex upon braking, but deemed it safe to haul an empty trailer as long as I gave myself plenty of stopping room. He is a steel expert and I accepted his advice and concern.

It is a 19 3/4" plate bolted to Harbor Freight's largest pintle plate, and it is all bolted together with grade 8 bolts and I welded on a piece of angle iron...which could be done a little bit better than it is I will admit.

This hitch has hauled m105's many hundreds of miles and m332's and m101's without incident.

I would have put a 3/8" triangle plate from the receiver tube all the way up to the top of your plate or welded some 3/8" x 2" flat iron on both sides of that front plate to stiffen it up - since it is so tall.

 

[therealsundance]

I had considered pulling the assembly; but decided best not to as I have no real authority perform said action.

I will be keeping an eye out for this vehicle while around town and should I find it, I plan to have a discussion on towing safety with them (next time, I will do my best to find the time to wait).

Theft isn't a good idea...But officer I was only stealing it because I think it was unsafe.

Just be prepared for him to say MYOFB.

 

[Preacherboy]

I would have put a 3/8" triangle plate from the receiver tube all the way up to the top of your plate or welded some 3/8" x 2" flat iron on both sides of that front plate to stiffen it up - since it is so tall.

If I planned on using this hitch for anything other than recoveries or permanently I would do some extensive mods to strengthen it. However, I would rather have it be smaller to haul m101's around...so it will come apart soon and this way it comes apart easier.

 

[papercu]

"Originally Posted by Preacherboy
Here is the one I built to get the needed 36" of height, but I will stress that I only use it to haul empty m105's."

If you only move empty trailers, why the need for the trailer to be level? Wayne

 

[Recovry4x4]

I infrequently tow M105s from GL lots when I win them. Usually do this with my suburban. For the infrequent trips I do, I stick with a factory assembled raised hitch bar and just deal with the nose down attitude of the trailer. Of the dozen or so that I've drug home like that, I've never experienced a problem and there were a few semi crisis stops in there.

 

[Preacherboy]

"Originally Posted by Preacherboy
Here is the one I built to get the needed 36" of height, but I will stress that I only use it to haul empty m105's."

If you only move empty trailers, why the need for the trailer to be level? Wayne

These trailers do not have jacks on them and the tongues are very heavy, it is much easier to have a hitch that is at the correct height. Also, it would seem to me that a trailer sitting level would be safer and pull better than a trailer that isn't...I don't know, maybe I'm nuts. I just seemed to make sense to me.

Don't worry however because I don't plan on purchasing anymore m105's they are too big for a pickup and when pulled behind a deuce I can't see it when I'm backing up! My dad has the last one and it is for sale, so it is time for me to take apart the hitch and get it back to normal.

 

[blybrook]

Theft isn't a good idea...But officer I was only stealing it because I think it was unsafe.

Just be prepared for him to say MYOFB.

I agree completely with this statement. I have no authority to pull the unsafe hitch and just took pictures to share.

I do plan to have a civil discussion with the individual should our paths cross at any of the local stores. I know it'll happen, this town isn't that big. Seeing things like this does get under my skin though.

 

[blybrook]

one has to remeber that when you extend the height or drop of the hitch jou greatly reduce the capacity.

This is correct. From my rough calculations of my particular riser with the hitch set where it is, I have reduced the overall capacity by about 1200 lbs. The overload failure should occur in the weld between the shank and the original plate.

Since the original hitch was rated for 10,000 lbs, I have no worries with what I normally haul as I still have a good safety factor in its capacity.

 

[Ridgerunner]

after we hooked up a m105 and noticed some flex upon braking, but deemed it safe to haul an empty trailer as long as I gave myself plenty of stopping room.

This hitch has hauled m105's many hundreds of miles and m332's and m101's without incident.

Preacherboy,

I don't think your hitch is much better than the one originally posted. Flat stock has hardly any strength in that position. Your pintle is attached, what....10" above the structural support bar. You admit, that it flexes already, while under braking conditions. Metal fatigues after continued flexing, and always seems to fail under the worst circumstances and time.

Because of your poorly designed hitch setup, you compensate by leaving plenty of room to stop your truck and trailer? What happens when an idiot on a cell phone, that doesn't pay attention to anything going on around him, doesn't know about your needed stopping cushion? Or the flat stock eventually just fatigues and snaps off?

Your last line makes me laugh You know that its a poor design, but yet you used it for "many hundreds of miles"

 

[Welder Sam]

i bought a 7 hole adapter. it has solid 2" sq stock and its properly attatched to the plate. the flat stock, i havent measured it but is obviously 1/2 to 5/8 thick was cut for the sq stock to be inserted into the material and welded on both sides. it has a gusset that goes all the way to the top. so be it, its not level for an m105 but its safe. expensive? yes. if ur gonna do something, be ready to pay for the good stuff or pay somebody to do what u need to do but have no clue about. nothing i trust came from harbor freight. thats just not smart

 

[Speedwoble]

This is correct. From my rough calculations of my particular riser with the hitch set where it is, I have reduced the overall capacity by about 1200 lbs. The overload failure should occur in the weld between the shank and the original plate.

Since the original hitch was rated for 10,000 lbs, I have no worries with what I normally haul as I still have a good safety factor in its capacity.

Agree with location of failure.

Disagree with your load de-rating. The original rating was based on an offset of ~6 inches meaning the joint is good for 5000ftlbs. (10000lb*.5ft) Offsetting it up to 12 inches means your new rating is 5000lbs or less. (5000ftlbs/1ft=5000lbs.)

 

[Speedwoble]

Metal fatigues after continued flexing, and always seems to fail under the worst circumstances and time.

And welding makes fatigue strength drastically worse.

 

[lacoda56]

Here's some pics of the riser I made for my M880 after making up an under bumper reciever.