005 — Direktlink
06.10.2009, 08:07 Uhr
robertd
|
Hi Alexander,
Just take a look at some of the data sheets of the big ones.
For example:
LIEBHERR LR 11350 has got two main winches, each equipped with 1500 m rope with a diameter of 38 mm. The maximum single line pull is 310 kN (1 kg equals 9,81 N, 1 kN = 1000 N).
The biggest hook block for the LR 11350 has got 2x26 lines, so we've got 2x26x310 = 16120 kN, or (divided by 9,81) 1643 t.
Now that's what the ropes and winches could pull theoretically - the maximum load for the LR 11350 are 1350 tons. So the extra ~300 tons are for safety reasons and (part of it) for loss, e.g. due to friction in the sheaves, weight of the rope or so. Of course the rope itself will take much higher loads due to safety reasons - the single line pull is given by the power of the winch.
For the DEMAG CC 9800 the values are:
rope diameter = 40 mm
length = 2x1540 m
single line pull = 352 kN
No. of lines = 2x26
so we get:
2x26x352 = 18304 kN, or 1865 t.
maximum capacity for the CC 9800 is 1600 t.
so if you take these dimensions and blow them up to fit your crane, you'll be on a good way. Just don't forget that the force depends on the cross sectional area of the rope - so if you've got a rope dia 80 mm it will (roughly) take 4 times the load of a rope dia 40 mm.
To determine how much sheaves should be used on the biggest hook block, there are some points to be thought about, for example:
- less sheaves should be better for assembly of the crane, since pulling the rope through the sheave isn't a really easy thing
- less sheaves also mean less rope needed for the same lifting height
- the maximum number of sheaves on the boom head on crawler cranes is usually given by the width of the boom head
- the sheave diameter, which is given by the rope diameter, could be a point when you get to the transport dimensions of the boom parts. I don't have a rule for it at the moment, but I think it's something like 20 or 30 times rope diameter = sheave diameter. I'd have to look that up...
So, there are much things you can think about when building a crane 
have fun,
cu,
robert |
. Now when I changed my idea about the winch (as I wrote above), no single part will be wider than 5m as far as I know except the boom 
If the crane superstructure will be ca 10m wide when it's assembled, how should I do with the boom parts 
