Are there high-hardness roll pins?

[LHaven]

We have a ProPride hitch. They come with two weight distribution "jacks" that you crank up to put tension on the transfer bars. They expect you to crank the jacks' hex stud with a "speed handle" socket crank, or a ratchet. As I learned with the scissor jack stabilizers on our last rig, if you have a cordless drill available, this decision is an idiot test.

My initial attempts to jack up the WDs with my cordless drill were only partially successful, as the drill stalled out before they reached the desired tension point.

A work colleague of mine counseled me that he never bought anything but drill-drivers anymore for serious work, so I tried his. Great success! I went out and got a light drill-driver to carry in the rig, just for this use. DW and I both love that she can do "her side" all by herself now.

After using it for about two years, we ran into a situation where the jack stud spun with no resistance and the jack didn't move. I popped the top cover and examined the linkage. A drive gear was connected to the crank rod with a roll pin; the roll pin had shattered, undoubtedly from the repeated hammering of the drill-driver. It was a relatively uncomplicated job to punch out the damaged pieces and replace it with a new pin. I bought four, figuring that the other jack was probably close to failure as well. Indeed, this last trip. I had to replace the other, leaving me with two spares.

Reluctant to go back to the manual crank methods, I'm wondering if roll pins come in different hardness levels? I haven't had much luck web searching this question.

[JRTJH]

Originally Posted by LHaven

We have a ProPride hitch. They come with two weight distribution "jacks" that you crank up to put tension on the transfer bars. They expect you to crank the jacks' hex stud with a "speed handle" socket crank, or a ratchet. As I learned with the scissor jack stabilizers on our last rig, if you have a cordless drill available, this decision is an idiot test.

My initial attempts to jack up the WDs with my cordless drill were only partially successful, as the drill stalled out before they reached the desired tension point.

A work colleague of mine counseled me that he never bought anything but drill-drivers anymore for serious work, so I tried his. Great success! I went out and got a light drill-driver to carry in the rig, just for this use. DW and I both love that she can do "her side" all by herself now.

After using it for about two years, we ran into a situation where the jack stud spun with no resistance and the jack didn't move. I popped the top cover and examined the linkage. A drive gear was connected to the crank rod with a roll pin; the roll pin had shattered, undoubtedly from the repeated hammering of the drill-driver. It was a relatively uncomplicated job to punch out the damaged pieces and replace it with a new pin. I bought four, figuring that the other jack was probably close to failure as well. Indeed, this last trip. I had to replace the other, leaving me with two spares.

Reluctant to go back to the manual crank methods, I'm wondering if roll pins come in different hardness levels? I haven't had much luck web searching this question.

Here's "all you'd ever want to know about roll pins (and then some)...

https://www.spirol.com/assets/files/...n-guide-us.pdf

To "summarize, they are all "hardened carbon steel" or " Stainless Steel,
Martensitic or Austenitic. Carbon steel roll pins are slightly harder/stronger than stainless roll pins of the same size. That said, carbon steel pins are more "brittle" than stainless, so may not work as well in a "near the limit high stress application".

Most of us would "just stick the pin in the hole and call it a day" but depending on the application, the rotation or the location of the slot can affect the pin's strength in a high stress environment. You may find that rotating the slot 90 degrees when you drive in the next one might solve your problem.....

[Ramtop]

Think of the roll pin as a safety device. If then is too hard and won’t break, when something jams, you will break a gear or shaft. Much harder and more expensive fix.

[LHaven]

Originally Posted by Ramtop

Think of the roll pin as a safety device. If then is too hard and won’t break, when something jams, you will break a gear or shaft. Much harder and more expensive fix.

I have given some thought to it as a strain relief. But the parts it connects are relatively massive, solid steel, as is the jack core. I'm sure it can afford to be at least a little stronger. Who knows, the replacements I picked up at Ace might already be stronger than the factory pins. I'll eventually know if I have to dip into my final pair of reserves.

That guide JRTJH posted is way better than anything I found on the web. I like the tip about placing the slot towards the shear force, and especially the one about adding an inner pin, though I suspect I won't find a pin skinny enough to fit inside these.

[NH_Bulldog]

I have used a small finish nail inside a roll pin to bolster it’s strength in other applications. Just remember, the whole point of the roll (shear) pin is that it breaks before something more expensive does………

[flybouy]

It's been said but roll pins ate there to prevent pther components from damage, much like a fuse in a wire. Using an impact driver is not recommended. Stick a roll pin in a vice and hit the length with a hammer and it will shear off. Same forces at play with an impact wrench, hence the term "impact".

[bobbecky]

Hopefully all are aware of the difference between a roll pin and a dowel pin. It's not just different names for the same thing. The roll pin is just that, a piece of metal rolled into an almost closed tube, where a dowel pin is a solid hardened rod that is used in similar applications but not usually driven into a tight hole where the roll pin is normally tight in the hole it is inserted into. The dowel pin will shatter if it is impacted but the roll pin will bend.

[BandT]

So just food for thought, roll pins must be soft to form them, then they heat treat them. By the thousands at a time, the ones in the middle get the proper heat treat, the ones on the edges maybe not so much. Just saying their is a HUGE variation in temper.

[GaryUT]

Originally Posted by LHaven

Reluctant to go back to the manual crank methods, I'm wondering if roll pins come in different hardness levels? I haven't had much luck web searching this question.

What you need is a heavy duty coiled spring pin instead of a roll pin.


https://www.mcmaster.com/spring-pins...d-spring-pins/


Gary

[JOglesby]

Just think about this. If it doesn't break it will likely bend. Hard=brittle, strong usually = malleable. Think cast iron. THere is a tough relationship between hard and strong. If it breaks the pieces come out easily and can be replaced. If it bends in the hole, how difficult will it be to punch out and replace? Something will fail over time, pick the lesser of the evils and go with what is easiest to replace.