Kumbbl

yes, indeed, this could happen - therefore my idea was changing direction only when car is driving straight ahead, i.e. both steerings are in center position - then they will remain in sync... but of course you are right, this could happen...

hmm, can not imagine ... tested several driving-ring based solutions and all of them have the backlash the driving ring has within the connected clutch-gear: You can simply test it: connect the driving ring to the clutch-gear so there is the power-connection. Then fix the clutch gear with a finger and try to rotate the axle - you will always notice that you can rotate the axle fpr about a quarter turn - must be because a driving ring has only 4 "tooth" which can grab the same 4 inner tooth of the clutch gear - and exactly the distance from one of these tooth to the next one will be the backlash... and this backlash can IMHO not be avoided when using driving-ring based solutions - regardless if simple or complex ones... or do you have another opinion? so therefore i can not imagine that you can test your solution without any backlash... ;-) anyway: in the meanwhile i agree with efferman: cause of the backlash problem only a sliding axle solution will work or something like the gearbox of Sariel - i have already tried this yesterdays, very cool and ingenious solution (as many of sariel) and can quite easily adapted to switch directions by by using his ratched as a somekind lever but then fixing the lever in one of the position comes up as new problem... I have a working solution fitting in the 8880 - based on a sliding axle - but for my taste it has some drawbacks: - not synchronized (sariels gerabox above is per se synchronized) - needs quite a lot of space so i must place the seats of the 8880 one stud more outside which could be acceptable but coudl also not ;-) Therefore my search for a really compact solution without backlash.... maybe i should think a little bit more about allanp's idea or sariels gearbox... nevertheless already now many thanks to all of you for your valueable hints and ideas! Klaus efferman, this sounds very promising! may i ask you for some construction details or zooms pictures of the inner details?

to be honest again: nope - Markus, have you built your solution in real live and tested? Take a look at your first picture, which the second driving-ring-element in blue: with your working green drive train you will have (supposing the left axle is the input and the direction is clockwise): - the green driving ring-axle is connected so therefore power goes to the middle left 16t gear which has direction counter-clockwise - therefore the green output axle has again clockwise direction (= same as input) Now take a look at the second picture where all three axles are green coloured (supposing again the left axle is the input and the direction is clockwise): - then the left middle clutch gear is jst an idler (because the middle driving ring is not positioned) (rotating counter-clockwise) to the second driving ring which is now connected so power goes to the right clutch gear (rotating clockwise) which - then drives the middle right 16t gear (counter-clockwise) which - then drive the output axle clockwise (same as the input) To make a long story short: regardless of the position of the drivings rings in your solution the output has always same direction as input... What i have i overseen, where is my error in reasoning? I have built your solution exactly as your pictures describe and it proves the story above... exactly - but not studdless but studded - but same prinziple....

My votes got for: - 8880 supercar: best mechanics - 8455 Backhoe: best pneumatics

to be honest: nope - reasons: - if i suppose the geay axle of the driving ring soild be the input, then there are two outputs, each with other direction but i need one output which changes direction - the main disadvantage is the high backlash which can not be avoided IMHO with driving-ring based approaches Thanks to all offering me driving-based solutions: But i have already built a driving-ring-based solution - all of them are basically the same - but all of them have this high backlash which makes them unuseable for me - reason see above... therefore my question for other innovative ingenius ;-) solutions with as low as possible backlash... best regards Klaus

Hi Markus, sorry, but it seems i'm too stupid for your hints ;-) If i understand your new picture (above) right, then inside each driveing ring is a so called "Technic Axle Joiner Inline", so there is a fixed connection between the two red axle endpoints, right? How you would get the reverse direction? IMHO this new picture does simply nothing... sorry, i'm far from offending you, but i do not understand what do you want to tell me - probably my fault... BR Klaus er... i believe, i do not understand your solution... probably I'm not experienced enough for it... may i ask you for some explaining words?

@Markus: Thanks for your reply, but hmm, just tried out and the result is not satisfying: - regardsless of the drivering positions the output has always same direction as input - or i have not understood your approach... - the backlash is as high as described in my initial posting - in my humble opinion a solution with no or minimal backlash can not be achieved with driverings... or i do not understand driverings.. ;-) Best Regards, Klaus

well, here we go: this is for a MOD of the 8880 supercar and its 4WS: in real 4WS-implementations the behavior of the rear steering changes depending on the car-speed: with low speed the direction of the rear steering is contrary to the front-steering (behavior of the standard 8880) to achieve a small turning circle and a good manoeuvrability whereas with high speed the direction of the rear steering is the same (but with much smaller steering angle) as the front-steering to get high stability for lane-changing on the highways etc... Now clearer?

Hello all, subject says quite all: i want to build a switcher between an input- and an output technic axle which allows to change the rotation direction of the output: so in one position the output axle rotates in the same direction as the input one and in the other position the output rotates reverse. Well, this seems to be quite easy with a gear driving ring, just tried it out in 15 minutes, but there is one KO-criteria for me: such a solution has always backlash of about a quarter turn (this is imanent for the driving ring) which is no problem for speed transmissions (e.g. for the reverse gear) but for my purpose this is not acceptable: i need a solution with minimal backlash. Well, an alternative is a solution similar to the unsynchronized gearboxes from the old supercar-days before the 8880 - quite simple to build but at least my try is really not compact but need " a lot" of space... Therefore now my question to all the building-gurus out there: Any idees or hints how to build a as compact as possible rotation-direction switcher with as less as possible backlash? studded would be most welcome... Is my problem-description described in an understandable manner? Many thanks in advance Klaus P.S. Please apologize my sometimes clumsy english writing...

uhhh? 8265 is a nice looking and well constructed set with lots of building fun but on the other side IMHO it is quite un-useable and un-playable without PF - unless you want to get a typewriter's cramp ;-)

Has anybody compared this Ultimate 8043 with the also famous JCB JS220 Excavator of Jennifer Clark (http://www.genuinemodels.com/jcb.htm)? if yes, which one yould you recommend concerning - building challenge - playing fun-factor - cost of parts - level of difficulty getting these parts at bricklink Thanks a lot in advance

well spoken... the 855 is a good example for this: Of course one can say "It's a limited crane without steering" but IMHO one can also say "What a genius design of the crane mechanics, lifting and extending boom work very very - as blackbird already said, for that time with these limited parts available, it'ts really very well done" 855 was one of my favorites when i was child... and it is a perfect basis for a MOC with 2 axle steering and a cab... if i rember right, the crane mechanics was also an inspiration of Jennifer Clark for her own mobile crane... so: no more comments necessary ;-) i fully agree... a very innovative set with great mechanics which is also in my Top-ten-list of the best technics sets ever but of course it is also somehow very special - so at least i can understand that people are disappointed and do not rate it high....

another one: The B-model of the crane truck 8258 is very nice and well done... almost worth getting a second 8258 ;-)

Hi all, i'm wondering what are the best B-Models of the Technics sets... My Vote go for the Formula 1 racer of the 8880: IMHO very well designed (better than all official Formula 1 racer sets of Lego and at least at the design level of 8458, at least from the perspective of an old school studded fan or at least hybrid fan), great playability and senseful features (8 cylinder, 2 shift gearbox, 4 wheel suspension, steering). Cause of the gearbox it is even better featured than official racers like 8458 or 8461 - at least IMHO ;-) What are your votes? Which other B-Models are great too? Thank you in advance... Kind regards from a new forum member (AFOL) who has left his dark ages since 3 month and who is already fixed on :-) Kumbbl