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Crane Project Updated

Wednesday, April 27th, 2011

Earlier this month I uploaded the final photos and descriptions for the crane project.

click to view Crane Project page

I finished the project a long time ago. I just recently got around to fully dismantling the pieces.

The Crane Project Page

Thursday, March 18th, 2010

I’ve blogged about this project already, and I’ve finally gotten around to making a proper webpage for it on my site. Although at this point, the webpage isn’t finished yet :-)

At any rate, I just wanted to announce it and get it out there:

click to view page

Turntable for Crane Project, Phase 1

Thursday, May 28th, 2009

For the first phase of my recent crane project, I designed a new turntable. The concept of this turntable is based on having a thrust roller bearing and also having the whole assembly centered about a solid core.

I first developed a 12-segment ring for the round bearing.

base of turntable
click for larger

This ring is based on “perfect” spacing, i.e. every other segment pins into normally-spaced holes. This basically means that the “round” ring is affixed firmly to a square frame and can be easily integrated with the framework of the crane.

geometry of turntable ring
click for larger

The next step was to create a set of rollers. The ring of rollers shown below is actually a new concept, one that I didn’t actually use in Phase 1. This new one is the same roller ring as the original, except that the holders for the rollers are on the outside of the ring instead of the inside.

with roller ring
click for larger

My new idea for this turntable was to have the whole thing centered about a solid core made of stacked Technic turntables. The core would extend upwards through the superstructure and contain a “cap” with counter-rollers to keep the whole assembly pinned together.

core of turntable
click for larger

One of the primary loads on the turntable is weight (vertical, downward load), but it also has to resist an overturning moment. For example, when a crane picks up a load, the whole thing wants to tip over. Therefore the turntable has to hold the superstructure down against the base, so to speak.

partial assembly
click for larger

The photos above were taken after I broke the crane apart into its main components. Here is a photo of the crane when it was assembled:

click for larger

Here is a diagram showing the cross section of the turntable. Note the different sections and bearings (rollers).

cross section diagram of turntable
click for larger

One component I haven’t shown in the photos is the assembly that actually centralizes against the Technic turntables in the core. It is a fairly straightforward design that uses two sets of four 24-toothed pinion gears (spaced at 12, 3, 6, and 9 o’clock). Two of these gears are powered so that the turntable can be rotated by a motor.

Phase 1 of this project proved that this turntable functioned well but couldn’t handle much load. The rest of the crane was robust, much like my marine pedestal crane.

When lifting, the overturning moment on the turntable pried it apart greatly. I pushed it until I felt uncomfortable, but I didn’t break anything. The solid core in the middle is just not strong or stiff enough to keep the superstructure flat against the base. The other downside was that it kept throwing rollers. The 2×2 round bricks would frequently pop off due to the flexing of the whole assembly.

So, in Phase 2 of this crane project, I’m going to try to redesign it.

Crane Project, Phase 1 Overview

Friday, May 22nd, 2009

About a year ago, I got the itch to build another large crane. I started a model and finished it in about two months. The final MOC (my own creation) isn’t really a finalized piece, but rather a project to test various ideas.

What really inspired me to build this were several ideas I had for a large crane, and this project turned out to be more of a testing phase than a real, finished MOC.

click for larger view

Specifically, I had some ideas about a new turntable design and also further development of using large plates to make beams for the framework (including joining them at an angle other than 90 degrees). I also spent the time to develop a compact winch package that could be reused on future projects.

click for larger view

I call this “Phase 1″ because I’m going to contunue to work on it. I created a 4-legged pedestal base for this crane to test out my ideas of joining built-up beams (made from large plates) at different angles. In “Phase 2″, I’m going to explore other ideas I have for a base – a moveable base :-)

In the next phase, I’m also going to redesign the turntable. The original design worked okay, but had its flaws. The most serious flaw is that it lacked the strength I wanted. The crane would just barely support 20 pounds on the main hook, and I I’d like to see 50 pounds supported or more.

I have other projects in the way right now, so it will be a while before I continue on with this crane. But first I need to take close-up photos of the components of “Phase 1″ so that I can present the ideas here.

More to come soon… :-)