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Ross Crawford / projects / cc2800 / stage2

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DEMAG CC-2800 crawler crane

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Stage 2

Under construction

Stage 2 adds a superlift derrick, and more sections to increase the length of the main boom.

Modifications

Enhanced the slew clutch - stage 1 just used a sliding worm gear, which worked OK but the locking mechanism wasn’t perfect. I decided to use a clutch mechanism, which meant there is a small amount of play, but is much more reliable. It also meant the engagement switch could be placed in a much more friendly position
Moved the remote connection point on the carrier - where it was, under the power distribution panel, caused it to foul on the tracks when slewing, so I’ve moved it further towards the rear
Diagonal bracing on boom narrowing section - in stage 1, the bracing went the opposite way on opposite sides of this section. Because the brace lengths weren’t exact, this created a slight “twist”. On the short boom that wasn’t a problem, but with the long boom it caused the suspension point to be slightly tilted, which worried me so I changed the diagonal bracing to match on opposite sides

Detailing

Some more detailing was completed, including:

Access ladders on each crawler
Attachments on each boom & derrick section for their matching lift rods
Warning lights and anemometer

Boom

Stage 2 adds additional wide sections to the boom, and also multiple narrow sections, which attach between the narrowing section and the tip section. They are just like the Wide sections, only 20 studs square instead of 22, and they come in a lengths of 5 & 9. Also added is a boom extension to allow multiple hoist lines.

I also built a heavy lift boom tip. This doubles as the luffing jib attachment in stage 3. I decided to include it in stage 2 to allow me to perform a lift test with the maximum lift configuration. Results will be posted here when test has been successfully completed.

Those with an eagle eye will also note that the boom winch has been fitted, in preparation for stage 3.

Derrick

There are also 3 types of sections used in the derrick:

First section (contains auxiliary luff winch)
General sections (multiple)
Tip section (contains luff pulleys)

First section

The first section is fairly short, and contains the mount point and luffing winch. The luffing winch, like the hoist winches on the carrier, has a selector allowing it to rotate freely or be locked, as well as driven.

General sections

There are 2 straight sections, 9 long and 5 long.

Tip section

The tip section contains the luffing block. The luffing line is 16 part, allowing the use of a single motor for the cable drum, thus reducing the weight. It also contains pulleys through which the hoist lines are run.

Boom extension

The boom extension is a short section, allowing a second hoist line to be used. It can be connected to the boom tip by 2 pins, extending the boom by 18cm.

Ballast

The derrick requires extra ballast to lift long booms. I decided (at least initially) to use books as ballast. Once the configuration is tested, I’ll look at some other kind, maybe steel plates.

The ballast is held on a “ballast tray”, suspended from the derrick. The tray is made of plate beams, similar to the carrier frame, and is suspended using the same braided line I used on all the crane’s winches. The cables have eyes at each end, made by tying them around technic bushes. I got this idea from Anders Gaasedal - he used it on his Gottwald AK 850-1. Thanks Anders!

Site last modified November 4, 2004 Home

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