A while back I was working on Branstetter Hardware with the intent to build an overhead crane to transfer between the loading dock and either/or truck and rail. Since that time the design has evolved some – such that it became more and more a 3D printing project. I’ve decided to pull out of the design portion of the Branstetter Hardware thread and stick it here by itself since this has become an ‘Overhead Crane’ project and not just part of the Hardware build.
At some point I may move more/all of the crane portion from the Branstetter Hardware build .. or not. Time will tell I suppose.
|Probably the greatest source for me for such things as this is Google Books. In a book titled “The construction of cranes and other lifting machinery”1 by Edward Charles Robert Marks, published 1904 we have, if nothing else a great source for inspiration. Chapter XII, Overhead Traveling Cranes, the first drawing provided that inspiration for me.|
Russel Greene pointed out that I had flipped the crane travel gears .. that the smaller pinion gear needed to be on the shaft with the larger gear on the wheel shaft.
I zoomed in to the drawing .. and yep .. he’s right. Green is the chain pulley and red the gears. I drew a line at the top of the shaft gear, one below at same distance and one at the bottom of the large gear. Obvious once it is pointed out!
From the book:
“The movable bridge consists of one or two cross girders, according to the load and span, secured to end carriages each of which is mounted on a pair of wheels. For loads not exceeding three or four tons, and a span not greater than 16ft. or 18ft., the cross girder may consist of a single rolled iron joist of I section. The span is the distance measured from centre to centre of rails. A 3-ton traveller, for a 15ft. span, should have a 12in. by 6in. rolled iron joist – that is to say, a joist 12 in. deep, with two equal flanges 6in. wide, and a weight of about 56lb. per foot; this will allow of ample margin for strength and stiffness. With a rolled steel joist of the section named the weight need not exceed 45lbs. per foot.”
My version measures 78mm/3″ (148″ full size) between centers of the rail, or a little over 12ft. full size The cross-girder is made from Evergreen #276 3/16″ I-Beam. The I-Beam is relatively over-sized but works ok. The flange width is .093″. Scaling up this gives me a flange that would be 18″ x 4-7/16″. Just a WAG on my part says that the slightly narrower but taller I-Beam should substitute for the 12″ I-Beam in the text.
- The construction of cranes and other lifting machinery By Edward Charles Robert Marks [↩]