On 11/9/2015 1:26 PM, Roland Jollivet wrote: > I don't see why it has be this way. Running a pump at full power past a > valve sounds daft. That's why the new pressbrakes, presses and injection > moulding machines use servo hydraulics. > > Simply put, you have a gear pump, and both ends go to a cylinder. Turn one > way, rod extends. Turn other way, rod retracts. Of course it's more complex > than that, but the idea is that if there's no work to be done, the motor > isn't turning.
If you could build a constant volume/displacement hydraulic system, with no accumulator or other buffer that takes fluid out of the main circuit, you could have a linear relationship between whatever moves the oil and the cylinder that gets moved. If you had a cylinder with the same volume and stroke, and same rod diameter, it should be possible to connect the end with the rod of each cylinder to the other end, without the rod to keep the two volumes the same. Push or pull on the external cylinder and the one on the machine should move the same amount. Connecting rod end to rod end and the rodless ends together wouldn't work due to volume changes. The cylinder pair would be locked up. How to drive it? Mount screws parallel to the driving cylinders and arrange them all vertically on a frame. One use for such a setup would be retrofitting old hydraulic CNC and tracer mills to modern CNC systems for faster speed. Those old Bridgeport hydraulic tracers could rip along at up to 13" a minute. Wheee. Looks like they would be a nightmare to keep running with all the valves and switches and pipes and hoses going to and from the tracer, the cylinders and the pump and reservoir. --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
