Another "myth to kill"??.....what makes it go???

[mmurphy]

Parasitic, weight, and leakage.(or a damned good magician!)

Also forgot thing called gravity, inertia, and unequal pressure.

 

[SPYDERLK]

:confused2: r we using scatter guns here?

 

[Egon]

[:confused2: r we using scatter guns here? /QUOTE]

Naw, sprayin fluid!

 

[AKKAMAAN]

:thumbsup:

I thought we were talking hydraulics here.

{ Wheel barrel } ?

Sorry guys, I was busy yesterday attending the PNW TBN picnic at dcyril's farm in Woodinville WA

Yes we are talking hydraulics....

but if we leave hydraulics for a moment, we all agree that we need force to move an object, or better said, make an object accelerate...

any object that is, mechanically connected to that object is going to move with it....that means the fluid in the lines will move together with the piston, piston rod, etc.and the object....what makes to object move is the same force that make the fluid move....how much fluid per second, (GPM flow), is not what makes it move, it is the force behind it....If hydraulic flow would be what makes an object move, the wheel barrel would not move when I pushed it, because there is no hydraulic flow behind it.....

If an hydraulic system is part of transferring the applied force to the object, then the object cant move if the fluid don't move. The fluid (hydraulic system) is just transferring the force that is applied by the prime mover. If we do not include the prime mover and the mechanical part of the pump into the discussion, we can say it is the force from pressure that makes the object move. When a hydraulic system is used to transfer force, flow is a condition for moving the object, but flow is not what makes it move...

When the applied force over comes the resisting force, the object will move (actually accelerate). If both applied force and resisting force is the same, object will stay in current state.
That's the meaning of Newton's first law....."Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it."

differential pressure causes it to move ... moving allows flow

SPYDERLK hit the nail on the head with his answer!!!:thumbsup:

 

[AKKAMAAN]

They can't.

Brian

edit- Back to the original question. Flow alone can make "it" go as long as as there is no resistance or load.

load is "it", resistance is "it" too....

 

[AKKAMAAN]

I will say yes. Of course pressure is needed to overcome the load. If I remember right, a pumps job is to produce flow primarily, and pressure is secondary.
Pressure that has no flow= no work, but potential work.

I would say the the pumps job is to maintain a consistent hydraulic link between the prime mover and the actuator....the same way as a chain drive....if the chain breaks, no transfer of force....

 

[AKKAMAAN]

Also forgot thing called gravity, inertia, and unequal pressure.

gravity, inertia, and unequal pressure are different "forms" of force

 

[AKKAMAAN]

If the river is flowing the Ram pump may be pumping as well as waterwheels turning various equipment.

But mainly it seems to be the state of the energy and it's application.:thumbsup:

Hydraulics where force is transferred in a totally confined system, is a hydrostatic system. Hydraulic power is a product of static Pressure and Flow.

Waterwheels, hydro power plants etc are defined as hydro dynamic systems.
Hydraulic power is the product of the mass of the fluid and its velocity.

Our mobile and industrial hydraulic systems are Hydrostatic systems.

Water wheels (hydrodynamic science) do not really apply on current topic

 

[AKKAMAAN]

If no flow, then no go. You could have pressure, you could have volume, but if the fluid is not moving, you have a static situation, such as an accumulator. The potential for work is there. A weighted load is another way to push fluid, and could exceed the pressure of a pump. When you ram that bucket into a dirt pile or a stump, the back pressure could exceed the pressure rating of any component in the hyd system.

"no flow no go" is OK to say......If there is a hydraulic link between the prime mover and the actuator, flow is of course a condition for motion, but still, flow is not what makes it move.....

I agree with your other points J_J.....some times our actuators become "pumps", and the force from inertia or gravity, will then be the "prime mover" force......and that will need work port relief valves to protect the and its components

 

[AKKAMAAN]

Pressure makes the flow make it go.

Bruce

:thumbsup: