Yair . . . some interesting comments from various posters concerning the way machines are evolving particularly in the application of hydraulics and electronics. I can remember probably in the late 'Sixty's when the first hydraulic drives appeared on various applications. We were told it was the way of the future and that many machines would use the concept and frankly we were sceptical with the 80% efficiency thing . . . you put 100hp in but only got 80 out I remember going to a field day and seeing a skid steer for the first time. It was possibly home grown and what intrigued me was that the engine slipped from the machine on a sub-frame and all components were accessible for maintenance and service. I think undo half a dozen hoses and the whole engine/pump assembly lifted out. This struck me as revolutionary as engines and power-packs could be mounted in any orientation, even crosswise in the frame. It didn't happen like that and these days I see an incredible amount of machinery and hoses/wires jammed in to such a tiny space. The advantages of not having a mechanical drive train seem to have largely been lost. The thing that really blew me away unfortunately didn't work . . . or it didn't work well enough and the old bush mechanic/farmer building it suffered a stroke which put him out of action. What he did was replace the steering clutches of a (I think) 2U D8 with five cylinder radial Staffa hydraulic motors. The bloody things were huge and it took some serious surgery on the housings to get the things to fit. They were machining up an adapter to hook some sort of hydraulic pump onto an 8v71 that was all mounted up in place. I understand they got it mobile but when the old feller got crook the project stopped. Imagine if that had worked. No torque convertor, transmission, or bevel gear and cross shaft. It was on a farm just out of Dalby and if any one is in that area even after all these years it may be worthwhile to ask around. Cheers.
Scrubby, What an interesting thread I think this is gunna be. I'll try to find him when i get time, but if you wanna go looking, there is a fella from out that way who posts on youtube. It's a while back since I saw him there, but I'm sure he had a vid on the "Forceful" tug in Brisbane and maybe some steam train outings, so if you can find him first, he might know the story. Lots of 'dozers and drotts now with hydrostatic drive, including some big Liebherr machines. I'm pretty sure our mate will have been disappointed, because the Staffa motors were not high pressure, so not a good match for axial piston pumps. Cheers.
The fella I was thinking of goes by the name of "flyingscrapyard" on youtube. I contacted him a year or two ago because I felt I might know him and that's how I know where he comes from. You better yell out next time you are down Hervey Bay way . Cheers.
I haven't seen any on heavy equipment yet, but I know EHA's (electro-hydrostatic actuators) are becoming a LOT more popular these days. They're a complete package, piston, pump, motor and valves all in one unit, 12 or 24 volt power goes in, hydraulic force comes out. Aircraft engineers love the things because they eliminate so many failure points, blowing a hose won't shut the whole hydraulic system down, and they make for easy maintenance, if one goes down, it can be replaced in a matter of minutes, while the old one is sent to the shop for repair.