Soft vs hard materials... who's the boss ???

[Suzuki4evr]

I have a question that no one could ever realy give me a clear answer to, and that is WHY does softer materials wear down hard materials. The usual answer I get is....."That is just how it is ". And that doesn't cut it for me. Cause in my mind it does not make sense at all. My brain says it should be the other way around. For instance a rubber seal wearing down a deep groove in a steel crankshaft seal landing. This is also the reason for making the material used in backhoe bushing and pins so that the bushing is from a softer material than the pin so that the pin gets worn down and not the other way around. So if there is anybody out there that can explain in layman's terms so that I can understand without getting too technical as to WHY this works this way,I would really appreciate it, because it boggles my mind. I hope I am not the only mind boggled person out there on this matter. Thanks to anyone that can answer this question.

 

[T Bredehoft]

How'bout this simple answer, the soft stuff (bushing) gets embedded with hard stuff (grit) and wears away the pin.

 

[Ulma Doctor]

How'bout this simple answer, the soft stuff (bushing) gets embedded with hard stuff (grit) and wears away the pin.

+1, i couldn't have said it better !!

 

[Sylvainmom]

The abrasion...

 

[woodchucker]

Besides, you never want hard and hard, it will gall. Just like you never want soft and soft.
So Tom's answer is perfectly simple. And its the same way a lap works

 

[Suzuki4evr]

How'bout this simple answer, the soft stuff (bushing) gets embedded with hard stuff (grit) and wears away the pin.

Well thank you very much. That was the first anwer I ever got that made sense. Now I can sleep easier at night

 

[Suzuki4evr]

I just want to know if that is the same when it comes to rubber vs metal?Because you don't see any metal in the rubber.

 

[Terrywerm]

Rubber is able to repel the grit, dust, dirt, etc. due to its elasticity, but the grit and such is still stopped by the rubber of the seal for a short period and it then wears into the shaft, albeit slowly. In the case of a rubber seal, it polishes the shaft for a long, long time before it wears far enough into the shaft that the shaft needs to be sleeved, reworked, or replaced. And by that time the seal has probably been replaced at least once if not more.

 

[Suzuki4evr]

Rubber is able to repel the grit, dust, dirt, etc. due to its elasticity, but the grit and such is still stopped by the rubber of the seal for a short period and it then wears into the shaft, albeit slowly. In the case of a rubber seal, it polishes the shaft for a long, long time before it wears far enough into the shaft that the shaft needs to be sleeved, reworked, or replaced. And by that time the seal has probably been replaced at least once if not more.

Thank you Terry. That is a good answer that makes things all the more clearer. I am just sorry that in all these years that I could not figure it out myself, but I suppose a guy can not know everything and it Is good to learn something every day. THAT is what I like about H-M. You can learn something or teach something here every day,and the people on this site is eager to help, even if we don't know each other.

 

[Bill W.]

I think we get to "know" each other by just spending time on the forum.
By reading what some of the more "involved" members on a day to day basis... you get to know them quite well.
You know who you are, and we all thank you... Bill W.