Water pump; I'm not a smart man...

[rracer5]

Originally Posted by Still Kickin

Here this might smarten you up; The threads on the screw act like a wedge or inclined plane, which translates force from the in-plane, rotation direction (torque) into an out-of-plane force along the axis of the screw. That is, when you rotate the screw clockwise, it applies an inward force to the screw by wedging its threads against those of the screw hole.

Once the head of the screw runs into an obstruction (when the screw is in all the way), turning it further begins to store potential energy in the elastic deformation of the metal, like compressing a spring. To convince yourself of this, consider what happens to a spring washer when it's placed between the screw and the surface. Clearly there is a constant force trying to push the screw back out. The same applies when the screw head simply compresses the surface it's screwed into, although a spring is a more efficient way to allow elastic deformation.

The reason the screw doesn't pop out immediately due to this outward force is because the friction of the threads is proportional to the axial force which pushes the metal of the screw threads into the metal of the hole threads. As the spring or outer surface deforms, the elastic force applied to the screw increases, which increases the friction of the threads.

Any questions? It's simple physics.

Brilliant!!

[CAT-RN]

Originally Posted by Still Kickin

Here this might smarten you up; The threads on the screw act like a wedge or inclined plane, which translates force from the in-plane, rotation direction (torque) into an out-of-plane force along the axis of the screw. That is, when you rotate the screw clockwise, it applies an inward force to the screw by wedging its threads against those of the screw hole.



Once the head of the screw runs into an obstruction (when the screw is in all the way), turning it further begins to store potential energy in the elastic deformation of the metal, like compressing a spring. To convince yourself of this, consider what happens to a spring washer when it's placed between the screw and the surface. Clearly there is a constant force trying to push the screw back out. The same applies when the screw head simply compresses the surface it's screwed into, although a spring is a more efficient way to allow elastic deformation.



The reason the screw doesn't pop out immediately due to this outward force is because the friction of the threads is proportional to the axial force which pushes the metal of the screw threads into the metal of the hole threads. As the spring or outer surface deforms, the elastic force applied to the screw increases, which increases the friction of the threads.



Any questions? It's simple physics.

I see not one reason why anyone would have a question!! Like you say --simple. I think that what you said. Maybe??

Russell

[youroo]

Originally Posted by CAT-RN

I see not one reason why anyone would have a question!! Like you say --simple. I think that what you said. Maybe??

Russell

The only question I have are the Screws "Metric or SAE"? Youroo! !

[Still Kickin]

And the answer is; Stop. What... is your name?
It is 'Arthur', King of the Britons.
What... is your quest?
To seek the Holy Grail.
What... is the air-speed velocity of an unladen swallow?
What do you mean? A metric or American swallow?
Huh? I... I don't know that.
He is thrown overboard
The Bridgekeeper says: Auuuuuuuugh. Sir Bedevere: How do know so much about swallows?

From the FR forum of course!

[CAT-RN]

Originally Posted by Still Kickin

And the answer is; Stop. What... is your name?

It is 'Arthur', King of the Britons.

What... is your quest?

To seek the Holy Grail.

What... is the air-speed velocity of an unladen swallow?

What do you mean? A metric or American swallow?

Huh? I... I don't know that.

He is thrown overboard

The Bridgekeeper says: Auuuuuuuugh. Sir Bedevere: How do know so much about swallows?



From the FR forum of course!

Off topic!! Still recovering from New Years I see !! Maybe. I think!!

Russell

[tom2t]

Originally Posted by grumpy0374

I would be callin Shurflo and rasing hell...o. Can just imagine what would have happened if you had needed to draw of your fresh water tank.

I would assume that since the motor is not attached to the pump assemblt, that the motor would run and the pump would stand idly by...hence no water.

[Mr. Dan]

Originally Posted by tom2t

I would assume that since the motor is not attached to the pump assemblt, that the motor would run and the pump would stand idly by...hence no water.

Right. See post #17 above.
Additionally, even if there were water in the pump head, it would not gush out of this cavity. There's never any water in this cavity... only in the pump head between the silver metal and the black plastic.

[Evereddie]

WOW! A scientific dissertation on screw threads and Monthy Python all in one thread. FRF rules. Such a full service forum.

[rockfordroo]

Originally Posted by Evereddie

WOW! A scientific dissertation on screw threads and Monthy Python all in one thread. FRF rules. Such a full service forum.

Nothing but CLASS on this forum!

[markb422]

Originally Posted by youroo

The only question I have are the Screws "Metric or SAE"? Youroo! !

He wrote, 10-32 pan head machine screws

[Still Kickin]

Originally Posted by markb422

He wrote, 10-32 pan head machine screws

Guilty as charged. I assumed youroo was paying attention, I should have known.

Monty Python

[chroniekon]

There is a good chance the screws might be metric since that assembly appears to have been made in mexico. In that case they may be 5mm which is only .006 bigger, but would fit a little tighter.

[markb422]

My question is how does a pump come apart like that. It looks like the pressure side of the pump is hard plumbed to pex. Does the plumbing vibrate enough to shake the pump apart like that.

[DreiHunde]

Doug, how did I know you were the OP just by reading the title of this thread???

You are too hard on yourself! Lol!

[ependydad]

Originally Posted by markb422

My question is how does a pump come apart like that. It looks like the pressure side of the pump is hard plumbed to pex. Does the plumbing vibrate enough to shake the pump apart like that.

Apparently it does vibrate enough.

I think it's soft lines on both sides, but it does vibrate like the dickens.

[ependydad]

Originally Posted by DreiHunde

Doug, how did I know you were the OP just by reading the title of this thread???

You are too hard on yourself! Lol!

You gotta have fun with it! This crap happens- you can't stop it.

[DreiHunde]

Originally Posted by ependydad

You gotta have fun with it! This crap happens- you can't stop it.

You gotta roll with the punches that is for sure!

[markb422]

Seems like every TT or MH I have had, had flexible hose on both sides of the pump which partially isolated the pump from the vibrations of the plumbing. Also, one of the first mods for every rv was to install a pressure tank to lessen the short cycling of the pump. Non of my pumps ever came apart like that.

[wahoonc]

Originally Posted by markb422

Seems like every TT or MH I have had, had flexible hose on both sides of the pump which partially isolated the pump from the vibrations of the plumbing. Also, one of the first mods for every rv was to install a pressure tank to lessen the short cycling of the pump. Non of my pumps ever came apart like that.

The Self Separating Pumps® are a fairly recent invention, probably to compete with the Lippert Non-sliding Slides®.

I will have to see if I have an older water pump laying around to compare the newer one with. I have not seen any mention of pumps falling apart until the past 2-3 years. I have one old pump that actually has a belt drive and motor is separate from the pump. It used to be in a 1975 Airstream.

Aaron

[BandJCarm]

I have no knowledge of where my water pump even is!! But I keep reading this post because I identify with anyone who says "I am not a smart man". Hey, you're smarter'n me........you found your water pump, and fixed it!!!