laamultiple
Agricultural
- May 5, 2014
- 2
Hi,
I've never specced any sort of hydraulic lifting system before and this has just come up on a project - just wondering if the collective minds here can sense check this for me to make sure I'm at least going about it the rightway? I feel like some of the values I'm getting for force etc are way out and I've never done this sort of application before so I don't know if my intuitive response is correct!
The application is a hatch which will open if struck by a force in excess of 5000N, and then a hydraulic cylinder will close the hatch again. This is shown in the attached image (roughly).
The approach that seems most obvious to me is a simple lever arm torque analysis to work out what size and pressure cylinder is required. In the attached image, the cylinder is indicated by the black lines. So for a torque calculation to get the force that will be applied to the line of action of the cylinder, I've taken 131.82 as lever arm, 1090 as radial arm and desired_force as the torque, using F = torque / (lever arm/radial arm) to get a target force, then using F = [pi/4(r2^2-r1^2)] * P to get a cylinder force which matches the target force (on the pull cycle of the cylinder) at a fixed pressure (in this case 2000psi if that's important). None of these values are restricted by design requirements at this stage, EXCEPT the desired force and the size of the hatch. The cylinder will be selected from a stock range from our hydraulics supplier, so I'm not too fussed about that.
I made a spreadsheet to rapidly iterate the changes to critical values - I've attached it, as well, in case I've just stuffed up a formula somewhere there.
Am I on the right track? I'm solo on this project and we're very busy at the moment so there's no-one else available to quiz sadly
I think it's right from an mathematical perspective, but I'd rather not proceed unless I'm sure!
Thanks in advance!
-La.
I've never specced any sort of hydraulic lifting system before and this has just come up on a project - just wondering if the collective minds here can sense check this for me to make sure I'm at least going about it the rightway? I feel like some of the values I'm getting for force etc are way out and I've never done this sort of application before so I don't know if my intuitive response is correct!
The application is a hatch which will open if struck by a force in excess of 5000N, and then a hydraulic cylinder will close the hatch again. This is shown in the attached image (roughly).
The approach that seems most obvious to me is a simple lever arm torque analysis to work out what size and pressure cylinder is required. In the attached image, the cylinder is indicated by the black lines. So for a torque calculation to get the force that will be applied to the line of action of the cylinder, I've taken 131.82 as lever arm, 1090 as radial arm and desired_force as the torque, using F = torque / (lever arm/radial arm) to get a target force, then using F = [pi/4(r2^2-r1^2)] * P to get a cylinder force which matches the target force (on the pull cycle of the cylinder) at a fixed pressure (in this case 2000psi if that's important). None of these values are restricted by design requirements at this stage, EXCEPT the desired force and the size of the hatch. The cylinder will be selected from a stock range from our hydraulics supplier, so I'm not too fussed about that.
I made a spreadsheet to rapidly iterate the changes to critical values - I've attached it, as well, in case I've just stuffed up a formula somewhere there.
Am I on the right track? I'm solo on this project and we're very busy at the moment so there's no-one else available to quiz sadly
I think it's right from an mathematical perspective, but I'd rather not proceed unless I'm sure!Thanks in advance!
-La.