Gantry Crane – Part I

The Crane
The illustration to the left is an overhead view of my pier. The On30 tracks are in red. That white block you see about middle of the pier represents a gondola or flatcar waiting to be unloaded/loaded. Th crane track is in cyan with two rails on either side of the On30 track and then an outrigger rail on the far side of the vehicular decking.
Here, I’ve brought the camera out at an angle so it may be more clear. The design of the crane by the way .. pay no attention to that. I just did a ‘quick-n-dirty’ drawing to give a general idea.

Note: This is just to give an idea of what the original wooden gantry crane might have looked like.

The Concept ..
– or – “The Reason behind the Madness” – more or less …

A modern gantry crane would not require that center rail – it would extend the entire width of the pier. By modern I mean something later then mine!

The DRRR as I model it, exists in my Alternate Reality about 1940. I figure the infrastructure is probably dated about 20 years earlier – 1920’ish .. which in turn since it was back-county narrow-gauge based on turn-of-the-century .. or practices in 1900.

Instead of steel beams they used wood. That then required that center rail. Now .. will my 1940’ish construction keep that wooden gantry crane? Shrug. Got no idea right now. It may have been replaced with a ‘modern’ steel gantry crane. If so .. that middle crane rail will be rusted up .. indicating it’s not used any more. I kind of like that idea.

Faller HO Early Wooden Gantry Crane
I found this Faller HO “Early Wooden Gantry Crane”. Thing is .. they are also braced at right angles. I can’t do that with my gantry crane on rails. To which I reply .. hmmmmmm.

Still. It’s a starting point .. if for no other reason .. then a point of argument.

Santa Fe Gantry Crane
With a lifting capacity of 25 tons, this gantry crane is 28’ high and over 40′ wide. It stands on two steel legs each 19′ wide at their bases, and rolls along rails with a track gauge of 37’9″. It can straddle several railroad tracks. It weighs approximately 20,000 lbs. (10 tons). It has electric traction motors at the foot of each of its two legs, which are powered by current from four overhead catenary trolley wires running above a wooden control shack on one end of the crane. It has considerable rigging gear that rolls along the top of the crane. Santa Fe cross-in-circle-­in-square emblems and “Santa Fe” are painted on its sides, as well as “25 Ton Cap.”’

Note: I brought the photo into Sketchup for a Match Photo. The I-beam/Bridge is about 4-ft deep. The text says that the thing has a 37’9″ track gauge. Mine would have a 20′ track gauge. Proportionally then mine would seem to require a girder depth of 2’2″. A quick bit of calculation shows that simply reducing the girder by 1/2 reduces the lifting capacity by 1/4 meaning it could only lift a little over 6 tons.

Now using ‘imagineering’. A W12-26 lb IBeam has a Kips of 49 for a 15′ span and a Kips of 24 for a 30′ span. (Kips = 1000 lbs or kilo-pounds). A W8-21 lb IBeam has a Kips of 27.That’s more then enough for some imagineering. If you halve the span then the IBeam needs to be 2/3 the depth to support the same weight. Therefore .. 48″ x 2/3 = 32″ .. which is what I will use to design my crane.

Conclusion – maybe
Prior: I think .. that the (imaginary) wooden gantry crane must have been a massive SOB. I’m thinking .. that a steel gantry crane riding on the two outer rails would work best. Leave the center rail rusty .. and unused.

Current: The gantry crane developed into the steel version. I’ve pretty much got the structure designed to the point I can start modeling. I haven’t done anything to the movable hoist – but figure some code 70 rail mounted on top of the I-Beams would be a good starting point.

I saw a photo of a gantry crane with an operator shack stick to the outside of one of the legs. I like that idea .. I think. Not really sure if I will go that far .. would make much more sense to operate from the ground with a cable but the operator platform/shack would add to the whole ‘scene’ .. as it were.



Comments

Gantry Crane – Part I — 12 Comments

  1. Can a N scale engine be used to operate the power direction left and right along the track. The foot of your crane would bear down on this (N) locomotive. This engine would be covered within the crane model foot. This concept also operate the crane trolley at the top. The N scale locomotive is covered in a shroud (inside the model)so all you seen is the N scale track. The question is can such a small motor handle the load. Also you need to slow it down and install sensors like those sold at “smart signal” to limited the travel within the crane footprint. I am attempting to build a O scale overhead crane for my Steel Mill layout. Any help would be helpful. Please comment

    • I don’t see why this wouldn’t work. The wheels of an N scale loco would fit nicely in an O scale scene to look like crane wheels I think. The other thing being you could remove the shell and weights and end up with a pretty small footprint with just the motor, drive and wheels for the N scale loco. Since the crane itself would be pretty big you have plenty of room to put the decoder remote from the engine etc. The N scale engine should have plenty of power as long as the crane moved easily. Interesting idea .. have to think about this over a cup of coffee.

    • NO POST…Sorry.

      Classic Toy Train issue November 2009 page 67-70 show how to add lateral movement to a Lionel Gantry Crane. By using a threaded rod and attach a low speed motor to entire model, now it can be made to operate.

      I also suggest looking bridge crane designs by “Model Structure ” on the net. They are showing two designs, both I recognize as something I saw as a young man back in Pittsburg used in the steel mills. One on these designs would fit my mill layout.

      The liner trolley track area would house the screw that operates the lateral movement of the gantry crane, at the bottom . The upper screw moves the carriage on the top. This would move the wench perpendicular to the tracks below. Both would be attached to the screw in the method shown in the Classic Train article. Now we have slow speed, smooth operation and torque. Your motor at 14 RPM would power the threaded rod, rotation.

      My machinist friend will help me with the model. He want’s to build the first model with plastic. I would like to build a later model out of brass for strength. Please advise recommend dimensions. Right now, I am figuring
      13″ wide X13″ tall the length 20″ +/-

      • Where can I find the operating wench? All motors should operate on 12-20 volts AC so it can pull, power off my O scale transformer.

  2. I found a winch at # VEX 276-2010. The assembly is 2.5″W X 2.5″L X 2″H ,it attaches to a 7V DC motor # VEX 276-2177 which is 2″ X 2″. So the mim. width of my crane carriage is at least 2.5″ and 2″ high. I will turn the motor parallel to the carriage sides and perpendicular to the track. The winch & motor will be hidden by the carriage house on top. I found a screen door roller assembly at stock #347-6912. It is 1 3/8″L X 7/16″W X 1″H the steel wheel is grooved and has a ball bearing roller inside. The steel grove wheel drops down another 1/2″ +/-. This part is sold in a packet of two. Any glass guy can buy from them but not open to the public. I am going to work backwards on my project and design the crane carriage first. I am going to try to keep my hand fabrication to the structure. I am a “High Railer”, so function is more important than scale for me. I plain to use a Lionel tin rail to roll my grooved wheel on top of the gantry crane

  3. Michael .. if you wish I can provided you a place to post up on this here on my blog. This is the kind of thing that needs to be shared, discussed etc.

  4. Gantry cranes can be with different designs and configurations to suit various applications. No matter what the crane is used for, it is necessary to choose a right and suitable one.

    • Well .. yeah. Thing is this is all a fantasy after all. If I could go back in time I could do a better design but … mostly I work by stumbling from one place to another

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