Best ever crane. Awesome. Possible best ever Technic
Posted by
BigMac
in Australia
on
30 January 2010
I bought this as new from Ebay for more than one year and just had time to finish this last week. I paid AUD 315, actually this is still the most expensive one I paid for, but definitely more than worth.
Before I build this one I found the Space Shuttle 8480 was the most sophisticated machine, and also I rate 8480 as the best Technic. now I think could be equal best as the second model of 8480, the submarine is also superb. Just by appearance the second model of 8421, I have not try yet, seems not as great.
Basically all the pros were mentioned by several very experienced collectors in this forum before, but I still want to reiterate several merits of the set,
1. The synchronized action of the extendable crane arms, the two arms ( smaller one inside the bigger) extending / returning at the same time. Very innovative attempt and the result is almost perfect.
2. The synchronized action of the extendable arms and the recoiling wheel of the cable for the metal hook. Good try but its not too perfect, as the speed ratio is not complying with each other.( see below for how to improve it).
3. Six wheels steering, first time in lego as I can remember, and with agreat result.
There are still two cons ( just for demanding collectors only) as below,
1. The strength of the pneumaitic cyclinders are not strong enough for heavy load, especially when the arms are fully extended. May be in future they can use the linear actuator, which is a bit stronger, to replace the pneumatics. Don't get me wrong, I still find pneumatics are good and easier to apply than linear actuator but just not enough power in this case only.
2. I dare to say that the design of the pnematic part of ths super set was not carefull enough. To have a better control of the down movement of the crane arm, as mentioned by another review before, the air outlet/ inlet of the pneumatic pistons should all been collected, cannot have the downward outlet open. The reasons is that the crane arm is very heavy, as the down section of the piston is open, air is allowed to release through the open outlet quickly without any control. Once the air presurre in the upward section of the pistons is leased the whole crane will bang down in one tenth of a second.
Improvements.
A. To reduce the difference of the speed ratio of the recoiling wheel and the extenable arms. I don't know wether you are willing to cut short for about 3 feet of the string. After cutting it, the hook can only reach the ground level not any further below. You have to measure it before you cut it, and make sure the length is right, as I do not know whether the length of this best quality string are of a standard length when came out of the factory. The reason is the diameter of the thread coil is too big when most of the string is returned to the coil, so the speed of releasing/ rewinding of the string would be much quicker than the extension or retract of the arms, sometimes making the movement out of control. After reduce the length of the string, it is still not 100% complying but the situation is much better and will have a better control.
B. To improve the pneumatics control, I added two air tanks to it. You may have to follow the suggested steps below, otherwise all the air stored in the tanks will released by just one downward movement. After the alteration, now, I can have crane arm ( 2/3 extended), at least six up and seven down movements with two full tanks of compressed air.
Step 1. Plug the only open outlet on the air switch, ie fully air tight, no air can go through. To avoid the air leaking from the tanks when switching to lower the crame arms.
Step 2. Connect the air tanks and fixed at the left and right side of the crane, ie. move together with the crane platform is being turned. Comnect the hose to the pump and tanks. If you have the patience to read up to here, you should know how to connect air tanks.
Step 3. Connect the TWO open ends of the pistons ( ie one on each piston) by ONE single hose. pierce the hose (perferrably about one cm from one end, so that it can be reused in future by renmove this end) with a thin pin, just pierce once, you don't have to see the hole, actually cannot be seen by naked eye. This is to controll the air relaesed from the pistons and hence the downward movement of the crane arm.
After the alteration, I still have to controll the switch very carefully and slowly, but its all under control. The above works quite well for my model. I don't think this alteration will damage the compressor or the pistons. Think about the recommendation to impove the machanics of your model, of course I cannot granantee anything here.
Any query write to me, may be I can send you the photographs of the alternations.
This is another super-superstar of Technic, Great work by LEGO.
Brickmad
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