Lego GBC Tower Crane (Bridge Module) is a Utility Module for bridging gaps in Table Layouts and was designed by Lawrie George.
The module stands over 80″/200cm tall (when on a table) and spans gaps of 36″/91cm, it is fully self-supporting and uses a 750gram counter-weight to balance the jib.
Idea and Research
My research was broken into finding real life cranes I could style my model from and search for key mechanisms to use.
The dimensions of the Crane are based on Stuarts bridge module, which is designed around a standard doorway 80″x30″.
I also took queues from Philo’s tower crane in regards to stringing the trolley.
| Type | AU | US |
|---|---|---|
| Doorway Height x Width | 2440mm x 760mm | 80″ x 30″ |
| Table Height | 733mm | 29″ |
| Bridge Height x Width | 1300mm x 920mm | 51″ x 36″ |
| Crane Height x Width | 1700mm x 2070mm | 67″ x 42″ |
| Crane Boom Height x Width | 1370mm x 1220mm | 54″ x 48″ |
Prototype
Once I had settled on the idea of a Tower Crane the next step was to create a prototype that would confirm that a structure of this size was even possible.
As you can see from the photo all the main elements are in place, the tower, jib, counter-jib, and counter weight.
Night Lighting
The module is setup for nighttime running using a mix of my custom Lego UV/Led lights, and 12V DC LEDs wired to Lego plugs.
Videos
Videos of the development and operation of this module.
- Inspiration and Prototype – 0:0
- Digital Design – 1:26
- Ordering Parts – 3:44
- Building – 3:56
- Assembly – 5:54
- Running – 9:00
An early testing video.
Building
The Mast and Jib were made up of identical sub-assemblies, making the basic structure quick to assemble.
Assembly
- The crane is designed to fold up and fit in a lamp style box, this makes setup and teardown very quick with the tradeoff being space needed for transport and storage.
Stringing Trolley
- Attach string to side of trolley opposite pulling direction
- Thread the string around the tensioner and run in through the middle of the jib
- Run the cord around the inner pulley on the jib
- Wrap the thread around the drum 3 times.
- This when tensioned provides enough friction to move the trolley.
- Run the string under the jib and attach to opposite side of the trolley.
- Ensure the spring is ½ way depressed to provide tension.
Stringing Hook
- Attach the string to the drum gear.
- Wind 2-3 turns around the drum
- Run the string under the boom and over the trolley pully
- Thread through hook.
- With the crane assembled, ensure the hook touches the ground
- Thread over the other pulley on the trolley
- Attach string to side the pin at the end of the jib
Weaving Catch Net
Nets are woven together using string to form a cone shape.
There are 3 rows
- 7 nets
- 3 nets
- 2 nets
Balancing the Jib
The jib needs a counter weight of 750grams to balance effectively.
The counterweight is designed to take Lego train weights but can also be filled with other objects to achieve the required weight.
Modules
| Pieces | Cost | Difficulty |
|---|---|---|
| >3000 | $$$$ | Complex |
A render of the completed model.
Version 1.10
- Update design of anti-jam kicker to have more weight
- Raise the hight of the lift conveyor to give balls more time to drop
- add more chain guides to stop chain jams at bottom
- Add a ram to eject balls that return down after triggering the anti-jam kicker.
Version 1.9
- Increase counterweight size to fit 14 train weights
- Add a blue double pin to the end of every liftarm to brick connection
- Add missing inner bracing to bottom of mast
- Remove bracing that was fouling with input
- Add missing bracing to top of mast
Version 1.8
- Add pins to reduce bowing under load
- Fix two pins in same hole
- Fix missing connector
- Some improvement to order of assembly steps
Version 1.7
- Change gear transfer between crane and input bit as knob-wheels were jamming.
- Add a clutch on the input bin drive
- Increase the height of the catch arms at the end of the boom
- Shorten the Jib stay to make the boom flatter
- Add additional lift arms to reduce load on jib support axle
Make support axle longer
- Increase Counter-Jib ballast weight to 750g to flatten the jib
Version 1.6
- Stop flag from rotating
Note: bar should be swapped for tube if the light is lit up
- Space IR receiver out more to stop it fouling on motor when jib is folded down
- Fix pin misalignment indrawing
- Add ½ pins to stop liftarm from moving
- Modify Platform to accept downlights
- Make drivers cab removable for easier packing
- Remove battery pack as it is inaccessible during shows.Requires cable run down mast instead
- Change Jib Pivot to stop it fouling on tower platforms
- Add a positive stop for motor rotation of hook up/down motion
- Split out ramp for packing
- Change gearbox design to
• Support removal for packing
• Have auto up/down mechanism
• Be disconnected from input bin
Version 1.5
- Reduce size of tabs on counter weight to make more room for battery
- Increase bracing on top
- Additional lift arm bracing in top
- Remove last guide lift arm as the balls fouled with it when going around the gear
- New counter jib tie design
- New jib tie design
- Updated Kicker to an anti-jam design
- Updated jib end to improve drop accuracy and stop balls bouncing off the top
- Add more wheels to trolley to stop jamming while moving
- Tensioner for trolley in-out rope
- Update Chain links to have a spacing of 9 between pins and a total of 233 links (9 x 26 = 234 – 1 = 233), this gives a top speed slightly faster than 1 ball per second and will allow the crane to keep ahead of surges.
- Add initial wedge to guide balls to chain
- Add more black support liftarms to inner structure
- Increase strength of bottom support frame
- Drive gearbox update
- Update input bin to include agitator
- Change output ramp design
- Add feet to tower
- Add braces to increase tower rigidity
- Add remote for trolley movement and hook up down (from Sariel’s design)
Version 1.4
- Wheels stop chain from moving and the pins jamming on the tower
- Ball guide stops balls from falling off pins
- Change the cab opening so the mini-figure can be replaced
