sometimes i get interesting jobs.

[pmsmechanic]

Only time I ever did fish plates was on dirt moving equipment. That was 1/2" and 3/4" thick material. I've read where guys say for truck frames don't go over 1/4" thick. If at all possible, I would fish plate both sides.

Shoot you just wreaked my plan. I had what I thought was a brilliant idea to just fish plate the outside as then the deck could stay on. Back to plan A.

Actually at first I was going to bolt a plate onto the outside of the frame to reinforce the frame but decided not to as then we wouldn't be able to easily see if the frame was cracking again. There is a reason for that. During feeding the deck and frame can get kind of sloppy with manure. I'd just as soon be able to check things without crawling under the truck.

 

[Shield Arc]

Shoot you just wreaked my plan. I had what I thought was a brilliant idea to just fish plate the outside as then the deck could stay on.

Well that sure beats nothing! You see truck frames with just the fish plate on the outside all the time.

 

[timster2]

I have seen many fish plates on the outside on single rail chassis when there is hardware, brackets, crossmembers etc on the inside of the rail. I have also seen fish plates with relief holes to go around rivets and mounting bolts as well.

 

[Sodo]

I was wondering too, why no doublers.

In this case the virgin frame material was insufficient. I would not normally trust that a weld could be stronger than what has been proven insufficient (the original frame). Also, a frame that's fatigued enough to crack (there) could have other subsurface cracks 1/4" away from the weld, just waiting for their turn to hit their limit. Doublers extending forward and back would not allow that nearby fatigued metal to experience the high stress levels that cracked it.

It's my opinion that the cracks all started at the flange, and fish plates would contribute less to strength than doublers on the flanges. I think doublers on the flanges are necessary (and I would add a fish plate too).

Those blocks will distribute the load in those conditions when the bed is firmly against the blocks. If the truck is driven with the bed raised then it's all on the rear hinge again. Which might be the condition that broke it (driving while dumping)? Or loaded, driving on uneven ground the bed can lift off the blocks. But the blocks are a good idea.

I don't see the cross member you added but I think the added stability will help to protect the frame flanges. Adding fish plates to the outside because it's accessible sounds like a good idea too.

Thx for posting, (with pics! ) :thumbsup:

 

[bcp]

Back in the early days of off-road racing, racers would box and strap their lightweight Jeep frames for strength, changing the "C" frame channel to a rectangular tube, and reinforced the flange.

Bruce

 

[pmsmechanic]

The cross member is in the first picture of my second post.

The bed stays attached to the truck all the time. There are two arms which pivot over the back of the deck, grab the bale and lift the bale onto the deck.

SA i was half joking when I said that you had wreaked my plan. But I must have some real tunnel vision on this one because it didn't even cross my mind then to just do them on the outside.

The cracks do start at the flange and then move to the outside of the frame. That's why I put the extra cross member in. I wanted to prevent that flex. I thought of doublers on the flanges and decided not to do it because if the frame cracks again then there is a real mess to clean up. This is already the second place the frame has broken. A previous owner had the lower flange doubled from half ways down the cab to the front of the springs. I also thought about boxing the frame but was concerned that I would just move the problem to another part of the frame. I stil think the best solution would have been to replace the frame with a heavier one but the customer didn't want to spend the money.

You guys have come up with some great ideas. One of these weeks I'll get the truck back and I will fish plate the frame. Thanks for all the ideas and for not tearing me to pieces. I was a bit worried about that.

 

[Big Barn]

Thanks for all the ideas and for not tearing me to pieces. I was a bit worried about that.

I think you're confusing us with Welding Web.

Terry

 

[Sodo]

I thought of doublers on the flanges and decided not to do it because if the frame cracks again then there is a real mess to clean up.

Agreed, there are conditions in usage where making a frame too stiff in one area can be the wrong solution. That's difficult to assess over the internet, you're in a better position looking at it in person. Often the cracked parts will tell you what motion caused the crack. For example, was it caused by forces lifting the bale? Or forces transporting the load? Or usage on un-even ground?

Is this similar to how the bale truck works? (from Google Images "Bale truck")

 

[pmsmechanic]

I believe the lifting of the bale caused the frame to flex in as the frame is bent in over the rear springs. That's why I added the extra cross member. That's also why I added the blocks between the frame of the deck and the frame of the truck.

Another part of the problem is that the owner is very rough on equipment. That's why it was decided that only his wife uses this truck to transport bales. The deck has been installed on this truck for about 5-7 years. I don't remember exactly. It took that much time for the frame to break so I don't think it's going to break again quickly but I do expect to see it again for repairs.

That's exactly how a bale deck works. The owner also decided to only transport one bale at a time with this truck. We will see if all these small changes do the trick.