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Old 06-16-2013, 07:55 PM   #21
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Just a guess but one of the reversing valves at the pump didn't switch and I bet you had pressure on both sides of the piston at the same time to do that much damage.
Call Lippert immediately and tell them what you have and what is the closest dealer you can take it to.
If pressures were the same on both sides of the piston, there would no motion to bend anything. Newton's 3rd law of motion. The slide had to be in a bind somewhere to bend the shaft.
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Old 06-16-2013, 08:22 PM   #22
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Originally Posted by OldCoot View Post
If pressures were the same on both sides of the piston, there would no motion to bend anything. Newton's 3rd law of motion. The slide had to be in a bind somewhere to bend the shaft.
Old Coot

Cylinder rod may move just because of the area difference, usually will extend, "piston side" , now if this was a double rod style cylinder area is equal so no movement but no reason for that bent rod though : thumbsup:
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Old 06-16-2013, 08:43 PM   #23
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Old Coot

Cylinder rod may move just because of the area difference, usually will extend, "piston side" , now if this was a double rod style cylinder area is equal so no movement but no reason for that bent rod though : thumbsup:
Made 2 assumptions, both cylinders the same size and also if it was a double rod cyl. No reason to believe the retract cyl would be different size than the extend as the loads should be the same in both directions, maybe a little less on the retract due to awning, etc. but not enough to require two different cyl sizes.
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Old 06-16-2013, 09:02 PM   #24
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I guess what I was trying to say is the system maintains about 1300 on both sides of the jacks and slide pistons at all times. To move valve allows pump pressure to admit to the desired direction of the movement, meanwhile its exhaust hose is allowed to slowly drain to the sump. Must maintain pressure both sides or the actuator "will take off". The bend occurred most likely because the piston was allowed to stroke too far outboard. The bend is most likely at the end of the stroke because its so close to the piston. The set up is to allow the piston to bottom out just as the gaskets are compressed. This looks like over travel of at least 1".
Not sure Newtons 3rd applies here, that action and reaction like a jet engine.

This is most referred to in Hydraulics.

Bernoulli's principle

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This article is about Bernoulli's principle and Bernoulli's equation in fluid dynamics. For Bernoulli's theorem in probability, see law of large numbers. For an unrelated topic in ordinary differential equations, see Bernoulli differential equation.

A flow of air into a venturi meter. The kinetic energy increases at the expense of the fluid pressure, as shown by the difference in height of the two columns of water.


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In fluid dynamics, Bernoulli's principle states that for an inviscid flow, an increase in the speed of the fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy.[1][2] Bernoulli's principle is named after the Swiss scientist Daniel Bernoulli who published his principle in his book Hydrodynamica in 1738.[3]
Bernoulli's principle can be applied to various types of fluid flow, resulting in what is loosely denoted as Bernoulli's equation. In fact, there are different forms of the Bernoulli equation for different types of flow. The simple form of Bernoulli's principle is valid for incompressible flows (e.g. most liquid flows) and also for compressible flows (e.g. gases) moving at low Mach numbers (usually less than 0.3). More advanced forms may in some cases be applied to compressible flows at higher Mach numbers (see the derivations of the Bernoulli equation).
Bernoulli's principle can be derived from the principle of conservation of energy. This states that, in a steady flow, the sum of all forms of mechanical energy in a fluid along a streamline is the same at all points on that streamline. This requires that the sum of kinetic energy and potential energy remain constant. Thus an increase in the speed of the fluid occurs proportionately with an increase in both its dynamic pressure and kinetic energy, and a decrease in its static pressure and potential energy. If the fluid is flowing out of a reservoir, the sum of all forms of energy is the same on all streamlines because in a reservoir the energy per unit volume (the sum of pressure and gravitational potential ρ g h) is the same everywhere.[4]
Bernoulli's principle can also be derived directly from Newton's 2nd law. If a small volume of fluid is flowing horizontally from a region of high pressure to a region of low pressure, then there is more pressure behind than in front. This gives a net force on the volume, accelerating it along the streamline.[5][6][7]
Fluid particles are subject only to pressure and their own weight. If a fluid is flowing horizontally and along a section of a streamline, where the speed increases it can only be because the fluid on that section has moved from a region of higher pressure to a region of lower pressure; and if its speed decreases, it can only be because it has moved from a region of lower pressure to a region of higher pressure. Consequently, within a fluid flowing horizontally, the highest speed occurs where the pressure is lowest, and the lowest speed occurs where the pressure is highest.
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Old 06-17-2013, 07:21 PM   #25
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If you want to get into Hydraulic laws Pascal is the guy, Fluid power engineering use Pascals law for force
Bernoulli laws are used for velocity, pressure drops in piping, and sizing hydraulic components, and pipe for proper Delta P

The word “hydraulics” generally refers to power produced by moving liquids.
Modern hydraulics is defined as the use of confined liquid to transmit power,
multiply force, or produce motion.
Though hydraulic power in the form of water wheels and other simple devices
has been in use for centuries, the principles of hydraulics weren’t formulated
into scientific law until the 17th century. It was then that French philosopher
Blaise Pascal discovered that liquids cannot be compressed. He discovered a
law which states: Pressure applied on a confined fluid is transmitted in all
directions with equal force on equal areas.
To better understand Pascal’s Law, lets use a bottle full of liquid as an
example. Let’s say the bottle has a 1 square inch opening. If we were to
apply 10 pounds of force on a cork at the opening, 10 pounds of force would
be applied equally to all sides of the bottle. This is expressed as 10 psi or
10 pounds of force per square inch. 10 psi represents the fluid pressure
of the system.
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Old 06-17-2013, 07:59 PM   #26
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Quote:
Originally Posted by win View Post
If you want to get into Hydraulic laws Pascal is the guy, Fluid power engineering use Pascals law for force
Bernoulli laws are used for velocity, pressure drops in piping, and sizing hydraulic components, and pipe for proper Delta P

The word “hydraulics” generally refers to power produced by moving liquids.
Modern hydraulics is defined as the use of confined liquid to transmit power,
multiply force, or produce motion.
Though hydraulic power in the form of water wheels and other simple devices
has been in use for centuries, the principles of hydraulics weren’t formulated
into scientific law until the 17th century. It was then that French philosopher
Blaise Pascal discovered that liquids cannot be compressed. He discovered a
law which states: Pressure applied on a confined fluid is transmitted in all
directions with equal force on equal areas.
To better understand Pascal’s Law, lets use a bottle full of liquid as an
example. Let’s say the bottle has a 1 square inch opening. If we were to
apply 10 pounds of force on a cork at the opening, 10 pounds of force would
be applied equally to all sides of the bottle. This is expressed as 10 psi or
10 pounds of force per square inch. 10 psi represents the fluid pressure
of the system.
Ok so more than these two gents made hydraulics available today. So lets change it to mechanics, what caused the piston rod to bend as it did? The bend appears to have occurred at near the end of the stroke. I checked mine today and the rods are all still slack in the thrust end brackets due the the lost motion in the piston rod lock nuts. I noted one that has only 1/16" clearance in the out position. If his setting was goofed by the repairer, than its easy to imagine the slide was full out while the piston still had stroke. That's what I believe happened to him. BTW the system is secret but best I can tell pressures are around 1200-1400 psi. The rod is 3/4-7/8 diameter plus it head and seal, that is a lot of force.......
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Old 06-17-2013, 08:25 PM   #27
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Your absolutely correct, the rod needs to be bottomed out in the extend position as stated before and then do your adjustments, but to have that type of bend im sure as you stated before it had to be out by at least 1"

Yes that is a lot of force, something has to break.
Sorry to the OP just trying top help
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Old 06-17-2013, 08:57 PM   #28
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Just did a quick calculation
If the cylinder bore was 2" @ 1400 psi and rod .750", force would be 4,400 lbs
At 1200 psi force is 3770 lbs
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Old 06-18-2013, 09:38 AM   #29
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To help the OP, I think we need to get back to what caused the problem to begin with. Something in the SLIDE is in a bind or the piston rod/slide attachment is out of adjustment. If the OP was to say to the repair person "Bernoulli's principle" he would be laughed at.
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Old 06-18-2013, 10:52 AM   #30
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Originally Posted by VinceU View Post
Ok so more than these two gents made hydraulics available today. So lets change it to mechanics, what caused the piston rod to bend as it did? The bend appears to have occurred at near the end of the stroke. I checked mine today and the rods are all still slack in the thrust end brackets due the the lost motion in the piston rod lock nuts. I noted one that has only 1/16" clearance in the out position. If his setting was goofed by the repairer, than its easy to imagine the slide was full out while the piston still had stroke. That's what I believe happened to him. BTW the system is secret but best I can tell pressures are around 1200-1400 psi. The rod is 3/4-7/8 diameter plus it head and seal, that is a lot of force.......
Vince, do you and Win know for SURE that the rod needs to be fully extended and then adjusted to that point? I spent a lot of time on Lipperts web site and found this..
Extending Slide out room
1...
2...
3...
4... Press and hold the IN/OUT switch in the OUT position until the room is fully extended and stops moving.
5... Release the switch, which will lock the room into position
NOTE: If the slideout switch is held after the room is fully extended, the control will sense that the room has stopped and will shut off the motor after a few seconds"

Seems to me that this may be a design issue. the rod end of the cylinder is not supported in any way, if it was it would not have had the 6 or so feet from contact point to contact point to be able to bend, it would have been more like 30" or so. I just want to get it fixed so we can use it and deal with any issues later. Already have one out, unfortunately the other one is bent as well. not nearly as bad but if I am going to do it right, I am going to do both. the problem with doing the other one is that one end is connected to the slide under the entry stairs..what a bi... just to get to it!
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