I saw this on ebay, and thought it was verry cool looking: http://www.ebay.com/itm/Original-Sl...95350?&pt=LH_DefaultDomain_0&autorefresh=true (and yes, I am the (only) bidder as of right now.. if I win the auction I'll post a copy of the image). Reportedly this is on the Frisco in OKC. The boom looks much more heavy duty than most of the small MOW cranes I've seen (that could be pulled by a speeder ) and it appears to have a counter weight attached to it, which I've never seen on an MOW crane this small. It looks like it was built on top of an old friction bearing truck, and it has yard air attached to it, so it must be air operated. On the boom end, there appear to be anchors attached to the rails. Anybody know what it would be used for? Paul
Whatever the story, I don't think I would be comfortable using crane (or any power cylinder) operated with air pressure. You would have no fine control of lifting and if a cable came loose from a heavy load, it would be really dangerous.
The crane is certainly a curious piece of equipment. My observations include: It rests on arch-bar trucks. There are not any grab irons visible There is not a visible handbrake There is not a visible air reservoir, either for storage or equalization The angle of the boom is fixed; the ladder is attached top and bottom The is not a winch or cable spool visible; the cable is fixed to the boom The vehicle lacks a hitch mechanism for towing or shoving There is a traveling sheave attached to the piston rod; therefore it seems that the “lift” function of the crane is binary, i.e., up or down. The device will lift an object just half the distance of the piston travel. The car has some function related to the RIP shed/track.
I have not seen this crane before, but I did notice the rail dogs that attach to the rail, to keep it from overturning. Similar tongs are used on bridge tie replacement type cranes. The rip track or wheel shop are also good thoughts. But it is designed to swing to the side with a load.
It could be an air over hydraulic unit. With the 2 piece looking cylinder, it appears that way. Air over units offer a more controlable unit than air only, and all you need is an air source, without the need for bulky, noisy hydraulic units. I have built some machinery using them.
Dan, I don't believe it is an air/hydraulic unit as there is a dump valve that has a nipple with an open elbow attached to it on the line, and there is no visible reservoir for hydraulic oil.
