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CAT | Cranes

This is the model of a 40 tons Figee level luffing shipyard crane, built during 2012 and 2013.  The model is 2,7 m high, and weighs about 13 kg, excluding the counterweight.

Below are some of the details:

Crane travelling

The crane is driven by two XL PF motors through big gear reductions. This made it very slow and still the motors were tripping after some time. I could only test this when the crane was fully assembled in my garden (it did not fit anywhere in the house), but then it was too late to make improvements.  

Slewing

For the slewing I used a droid gear wheel, driven by two medium PF motors.

In this photo the top of the crane is removed. The motors are visible and so is the gearing. The tipping moment is transmitted by pulley wheels (with tyres on) to the inner rim of the droid gear wheel. The weight of the upper part is carrried by a turntable, which act as a thrust bearing on top of the portal of the crane, just as in reality.

The turntable is seen on top, the slewing assembly is topside down on the table.

Hoisting

Both hooks have their own winch, medium PF motor driven. The winches are similar. The auxiliary winch is seen here:

The ropes are silk kite wire and run over pulleys which are drilled out to make them revolve independently over the same axis.

The jib tip:

The main hook:

Luffing

The luffing motion is very smooth, being well balanced by the counterweight.

The counterweight consists of boat weights and lead pellets.

The crane in reality:

See video on YouTube

The model on YouTube

 

 

 

 

 

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Dec/10

26

Lemniscate crane

During the building of the Bailey tower crane I was inspired by the Lemniscate cranes working in the port of Vlissingen and Terneuzen for the  discharging  of mainly coal from ocean going bulk carriers. The graceful movement and perfect balancing of these cranes offered a real challenge  for building a Lego model. When one of these floating cranes came in drydock on the shipyard I’m working on, I got the opportunity for a closer look, take pictures, and, even better, I was able to get a copy of the General Arrangement plan.  Initially, I decided to build the crane in the livery of our client  Ovet, but after checking my Lego inventory, this proved to be too expensive. The Ovet colours are mainly gray, yellow and green and I would have to buy too much parts. Searching the internet I found out that in the port of Amsterdam, the same cranes are working, in a yellow, blue and black colour scheme. This proved to be more suitable, financially.

I decided to built to scale 1 : 30. The Bailey tower crane, I built before was 1 : 20, but I expected too much problems with the moving masses typical for this type of crane, when using this scale.

Specially challenging for this built were the slewing bearing (always!), the grab operation and balancing the jib movement.

The slewing bearing is documented  in the post “Slewing bearing 150 mm”, on this site.

The jibs are balanced with counter weights. These counter weights must be positioned as low as possible for stability, as the crane is mounted on a floating pontoon. When the crane is at rest position (at minimum outreach) the counter weights are horizontal, with the weight as far forward as possible. To get balance in the model, while using lead pallets for weight, I had to deviate a bit from the dimensions of the original by extending the counter weights a bit longer forward.

Following movies show the various motions of the crane model:

Slewing

Luffing

Grab operation

Grab operation was achieved by building a two drum winch, driven by an adder-subtractor gear. See movie below:

Credits to Werner Verhage of Ovet, who gave me tour through his crane no. 9 during his lunch break.

Below are some details of the crane and the pontoon on which it is built:

The pontoon during construction.

The pontoon during construction.

Pedestal, with crane removed.

Pedestal, with crane removed.

Mooring winch details

Mooring winch details

IMG_1488

Luffing gear

IMG_1475

 

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