On 11/9/2015 5:37 AM, andy pugh wrote: > On 9 November 2015 at 03:54, TJoseph Powderly <tjt...@gmail.com> wrote: >> messy ( plan on leaks and kitty litter ) >> the hydraulic supply tops up the volume from a reservoir that you keep full >> these are really really beefy systems. > Indeed, the power pack for my testing machine was contained in a > soundproof wooden box about the same size as a car. > At work there is a bank of 20 x 75kw (100hp) motors servicing a > hydraulic ring-main for about 6 multi-axis shaker rigs. > (But the rigs can play-back suspension /braking / acceleration forces > and displacements on 4 wheels of a vehicle in real-time 25 hours a > day)
I've done quite a bit of hydraulic servo work for custom machines. You can use regular industrial cylinders for positioning. For precise positioning and fast response you need to use a lot of steel lines. Rubber hoses act like springs as they bulge and contract. Servo valves are expensive. $1000 is not a lot for a servo grade proportional valve. There are cheap proportional valves but they are not made for precise positioning. Some are just used for pressure control and are very slow to respond. A swash plate piston pump can eliminate a lot of oil heating problems and energy waste. But swash plate piston pumps are much more expensive than gear pumps 3-4K for a 20 hp pump is pretty cheap. You can get by with a smaller pump by using an accumulator but those are thousands of dollars each also. These are all reasons why people have migrated to electric servos and away from hydraulics. Dave ------------------------------------------------------------------------------ Presto, an open source distributed SQL query engine for big data, initially developed by Facebook, enables you to easily query your data on Hadoop in a more interactive manner. Teradata is also now providing full enterprise support for Presto. Download a free open source copy now. http://pubads.g.doubleclick.net/gampad/clk?id=250295911&iu=/4140 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
