Texasmark
Supreme Mariner
- Joined
- Dec 20, 2005
- Messages
- 14,778
Was trying to go to sleep awhile ago. Couldn't. Reason was these new hubs that folks are talking about.
Been told that you have to torque it to 100 ft-lbs to get the Delrin to fully seat against the thrust washer.
Delrin is a semi soft plastic; used in the aerospace industry (among other places) because of dielectric constant, machineability, and stability in harsh environments.
In the prop I have (Hustler), with the new fancy hub, there is a brass/bronze splined hub
that connects to (slides over) the propshaft and that brass hub has fins on it (around the outer circumference). These fins are cast into the Delrin and the Delrin is then slotted on it's circumference to accept slots on the ID of the propeller casting.
You aren't going to put 100 ft-lbs of torque on Delrin....it will cold flow and move out of the way or desintigrate (crumble).
I think the 100 ft lbs is a seat of the pants cover up job to get it to work. I think that the originator of the memo/service bulletin/ what have you, had a table full of props with the guts ripped out of them and decided that if you smash all this stuff together hard enough it can't disentigrate..............nor can it slip either.
What you do is put 100 ft-lbs on the brass/bronze tube that is splined to the prop shaft. The Delrin transmits torque from the center hub's splines to the prop. So if you smash it all together hard enough, there is no place for the Delrin to go when it gets smacked.
i'm here to tell you that the prop I have will not slip like a rubber slip clutch can slip. This prop is locked together via the Delrin and you hit something with this baby and parts are going to go a flying.
I read all the yakin about what this new hub is supposed to do, but I think somebody is blowing smoke. :|
With that said, I can't understand why the design. If it's because rubber slips on high hp engines, then ok. But this sucker is not going to slip. It will tear.
I would appreciate directions to engineering data that discusses the reason for the new hub and how it is supposed to do what it's supposed to do cause I can't see it from here and 100 ft-lbs ain't the answer; leastwise not in my limited electromechanical engineering mentality.
Thanks,
Mark
Been told that you have to torque it to 100 ft-lbs to get the Delrin to fully seat against the thrust washer.
Delrin is a semi soft plastic; used in the aerospace industry (among other places) because of dielectric constant, machineability, and stability in harsh environments.
In the prop I have (Hustler), with the new fancy hub, there is a brass/bronze splined hub
that connects to (slides over) the propshaft and that brass hub has fins on it (around the outer circumference). These fins are cast into the Delrin and the Delrin is then slotted on it's circumference to accept slots on the ID of the propeller casting.
You aren't going to put 100 ft-lbs of torque on Delrin....it will cold flow and move out of the way or desintigrate (crumble).
I think the 100 ft lbs is a seat of the pants cover up job to get it to work. I think that the originator of the memo/service bulletin/ what have you, had a table full of props with the guts ripped out of them and decided that if you smash all this stuff together hard enough it can't disentigrate..............nor can it slip either.
What you do is put 100 ft-lbs on the brass/bronze tube that is splined to the prop shaft. The Delrin transmits torque from the center hub's splines to the prop. So if you smash it all together hard enough, there is no place for the Delrin to go when it gets smacked.
i'm here to tell you that the prop I have will not slip like a rubber slip clutch can slip. This prop is locked together via the Delrin and you hit something with this baby and parts are going to go a flying.
I read all the yakin about what this new hub is supposed to do, but I think somebody is blowing smoke. :|
With that said, I can't understand why the design. If it's because rubber slips on high hp engines, then ok. But this sucker is not going to slip. It will tear.
I would appreciate directions to engineering data that discusses the reason for the new hub and how it is supposed to do what it's supposed to do cause I can't see it from here and 100 ft-lbs ain't the answer; leastwise not in my limited electromechanical engineering mentality.
Thanks,
Mark
