Here's some recent work on the front steering setup. I built this in April of '08, but had a lot of bugs to work out of it. Last night, I got the steering linkages working like they should, using model airplane linkages.
That the front wheels steer tighter than the rears is deliberate, and that's why the connecting rods are angled.
Here's a look at it from the side. This was in the middle of redoing the hangers to allow the whole unit to tilt fore and aft on the main frame of the carrier for better tire contact with the earth.
Last Edit: Feb 16, 2009 18:36:02 GMT -5 by Southgate
counterweights, that is. I got some work done on the counterweights. I had my brother cut these crescents for me months ago, he works in a fab shop with a burn table. Note that the base unit is tack welded together
I fully welded the base unit and ground it smooth, then used a flap disc to smooth it even further. the same was used to smooth the edges of the rest of the counterweights. Here is the base unit sitting on top of some unwelded extra pieces.
Using a lathe and a drill press, I made these pegs. I further rounded the tops by putting them in the lathe and filing them while it was running.
The holes in the pegs are for lifting purposes. Since the pegs are slightly shorter than the counterweight slabs are thick, there is a hole in the bottom of each slab that aligns them as they stack.
Thanks, Guys! Bonze, I wasn't aware that cranes do carry propane tanks. I'll have to look into it, I guess.
I also got some molds made for the shackles to make resin copies. The copies have to be drilled. I also included the pins in the molds, but didn't really expect them to be that good, but they might just work. If not, they aren't hard to make in brass or styrene. The resin shackles are stronger than I anticipated.
Bonze, PM me your address, I'll send you a few copies for your crane project.
You've seen the counterweights, now here's the system that helps install them on the crane. The crane picks them up with its hook and stacks them on it's frame, on a special slightly raised platform.
When it has loaded all it is going to use, the upper unit swings around and slips it's counterweight platform into the slot in the base weight. Then that raised platform lowers, leaving the counterweights sitting on the upper unit. This self loading is pretty much a standard feature of modern cranes.
Here they are still on the carriers' frame platform.
Now they are in the upper's platform. Note the relative change in the gaps. The counterweights are not touching the carrier's frame now.
On a real crane, this action would be hydraulic, a bit much to as of a small model. Here's how mine works:
These are 2 halves of a "carriage" that moves forward and back in the carrier's frame, activated by a motor with a gearhead transmission, attached to a threaded rod. As the rod spins it slowly pushes or pulls the carriage to or fro.
There is a little "cart" that rides up and down on those wedge shaped ramps in the carriage. The cart is held in place by a connecting rod attached to a crossmember on the carrier's frame, so it can go up or down on the carriage, but not to or fro with it.
Here's the threaded rod, it is threaded through the brass end on the carriage. The motor is arrached to a crossmember in the carrier. The threaded rod doesn't contact the cart.
I got one of the outriggers, however incomplete, mounted on the carrier's chassis. Now the crane can swing the upper unit 360 with the counterweights without falling over. The outrigger is easily removable, as on a 1/1 for transporting. The rear one will be too.
I'm making the crane to be totally remotre control, I'm going to make the lower (carrier) separate from the upper, each will have it's own radio. Kinda like getting out of one cab and into the other. There is a lifting system in the carrier's frame for lifting the counterweights onto the upper unit so the crane can be self erecting. This mechanism is the heart of that.
The carriage, with ramps on it, moves forward or backward under the cart, which only moves up or down, not forward. The cart is linked to a crossmember on the carrier's frame. here's another angle of the drive motor with a slow speed gearhead.
Between that and everything else going on between the frame halves, there's not much space left for the RC equipment. So I thunk up a way to put 2 of the 6 "C" size batteries in the fuel tank, freeing up appreciable room in the space left for the other RC batteries and receiver, other stuff.
This fuel tank can hold two batteries.
End comes out:
I took the crane to the Portland NNL last weekend, even in it's incomplete state it was well received, got lots of attention. I stuck a cab and front end from a Payhauler kit on the carrier to give it a sense of proportion.
Anyway, the show is over, it's back to work on the crane! Long way to go...
Last Edit: Apr 26, 2009 19:35:06 GMT -5 by Southgate