Roll on the 20th June

[fletcher]

Well, if it's a closed piped water system with piston each end then if the gate end is slightly higher than the house end then when you step off the piston or unlatch your leverage device used to create the hydraulic pressure, then the height of water at the gate end will try to equalize with the house end pulling the gate closed [needs sufficient head of water to overcome head losses in pipe work] - simpler to have the gate mounted at an angle as said.

[ramset]

Archer good observation  Stress  pressure  struggle etc etc changes things  Chet

[The Eskimo Quinn]

try this,

for a farm gate, an inside bowl from a washing machine, a single water dump down the chut lowering the drum/bowl against a single pulley wheel to the gate and it opens, there is a senond rope on the bowl to an overhead pulley that simply goes to a small 10kg counter weight.as the water drains through the small holes the counterweight raises the bowl and closes the gate.

or if you were an egyptian, you would simply have a small amount of water onto the end of a lever/fuclrum beam at ten to one and get the same result.

[CLaNZeR]

Very good use of physics for the gate, but it has to shut itself, no second action required, no slanted gated(same as slanted or centalever hinge) Still shows how simple it is though.

The gate is mounted on a slant, so stopping the water flow, will release the pressure on the paddlw and will allow the gate to return to its shut position.

Replace the water with a long stick if you want, as long as the pivot is correct, it will take minimal force to move a great weight.

Or even easier, piece of twine to lift the latch and get the visitor to do the work by telling them to push the gate!

[CLaNZeR]

Just get the gate to close itself after you walk through, a paddle wheel would need too much water to move hundreds of kilos.

Ok so after 2 things with one hit.

1.) open the gate with one hit
2.) Close gate with reaction from same hit and no extra energy.

Get the gate balanced right, control the motion and speed that the gate opens, hence giving it enough time to open and then the re-balance will automatically close it as it find it way back to a balance.

Secret is the speed you open the gate, because it will take the same speed to close and you need it slow enough to let the person walk through.

ummmm thinking now.