On 14 May 2012 13:41, Dave <[email protected]> wrote: > There were/are some manufacturers of hydraulic cylinder driven milling > machines.
I used to drive a servo-hydraulic tensile-testing machine. The actuator was extremely stiff and extremely fast. And _extremely_ expensive. That particular one used a leaky piston and leaky end-seals (actually hydrodynamic bearings) with separate scavenge pumps. The truly expensive part was the Moog Valve, which is an electromechanical proportioning valve, which applied differential pressure to either side of the piston. That was my first introduction to PID. It was necessary to re-tune the PID for each design of tensile specimen, as the stiffness changed. It could run at 20 tons / 5mm / 50Hz. The hydraulic power pack was the size of a small car. At work they have test rigs using the same style of actuator Those run 20 tons / 250mm / 50Hz. The hydraulic power pack is 20 x 20hp pumps feeding an 8" dia 10,000psi ring-main. The pipe fittings look expensive. http://www.toyota-motorsport.com/slideshowpro/albums/album-20/lg/Full-Car_Road_Simulator1.jpg Is an example. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
