AndroTech

9398 - Lego Technic 4x4 Crawler

1086 posts in this topic

When will we see more pics? Also I wonder what the B model will be! Does anyone have any idea how capable this might be for trials?

I'll be buying a fresh set of lithiums for this baby :)

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2 diferents motors conect to the same RC channel with a return to center steering always will be syncronized.

Is it confirmed that this has return to center steering? Return to center doesn't seem like a good idea in a crawler truck like this that is going to have it's wheels in all sorts of different positions that may be calling for the wheels to return to normal, but they can't because there is stress on them. I would think full control of the steering would be the way to go. :sceptic:

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Is it confirmed that this has return to center steering? Return to center doesn't seem like a good idea in a crawler truck like this that is going to have it's wheels in all sorts of different positions that may be calling for the wheels to return to normal, but they can't because there is stress on them. I would think full control of the steering would be the way to go. :sceptic:

Always can remove the return to center brick, I think is the piece just before the front and rear motors, all this if the mechanism are like I think :laugh: .

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2012Lego18.JPG

2012Lego17.JPG

Source, at this site there also some pictures of other upcoming sets (themes like, Dino, Friend and Ninjago).

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Because the motor is in the front axle, and the IR receiver is in the rear end, the motor should have a long cord or extension cord to reach IR receiver, which is mounted behind on the bed. BB could be under the hood. Just my 2c ....

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Do we know if this has any differentials in it?

I think so, if you look carefull we have 7 studs between the last visible gears, I think that we have here the 5x7 liftarm structure with the diferential inside, another reason for differentials maybe the good movement and handling of the set, a trial truck without diferential haven´t got this fluid displacement.

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Sigh... the more i look at this model, the less likely it is that i will buy it. okay, it looks cool to be certain, but:

a.) it's expensive, especially given the part count ($223 dollars. ouch.) :pir-angry::thumbdown:

b.) no new parts aside from the motors, what the crap. it's not like the new servos are even tremendously useful, and the same function could have easily been achieved with existing parts. seriously, why did they do the whole new motors when existing ones would work? and worse, they missed a very good opportunity to reintroduce a radio control system. :pir-cry_sad:

c.)the build is not particularly challenging or innovative.

d.) they missed a lot of details, like a fake engine, and cockpit steering.(it doesn't even have functional headlights, which it totally should.)

e.) all in all, i think they missed a good opportunity to do a true supercar, with locking differentials, adjustable suspension, and all that.

in relation to the unimog, this set is a bit of a let down. i mean, the unimog was not perfect,but it had 4 wheel drive, suspension, and all the functions. it was challenging to build, and well engineered, and this just seems thrown together.

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b.) no new parts aside from the motors, what the crap. it's not like the new servos are even tremendously useful, and the same function could have easily been achieved with existing parts. seriously, why did they do the whole new motors when existing ones would work? and worse, they missed a very good opportunity to reintroduce a radio control system. :pir-cry_sad:

d.) they missed a lot of details, like a fake engine, and cockpit steering.(it doesn't even have functional headlights, which it totally should.)

e.) all in all, i think they missed a good opportunity to do a true supercar, with locking differentials, adjustable suspension, and all that.

b. i am sure the cost of development for the new motors took up the entire budget for new parts in this model.

d. once again i am sure that the motors were the priority, and other parts could not be added into the set without a significant price change.

e. this is only lego you know...

tim

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From the pictures and video I discerned these things:

Looks like the form of the drive motor is 3-wide x 4-high x 5-deep, with a 3x3x2 bracket on the front, in keeping with the ones for Linear Actuators. The bracket provides the side-facing holes for the front motor mount, to complement the rear holes in the motor casing. I suspect there might be an axle extender inside it, such that there might be a 2M axle into the motor (or a 1M axle protruding from the motor, leaving more space for gearing inside the motor casing), with a 4M axle carrying the 12-tooth cog, which might be the tan one.

The reason the steering seems to be moving to the end stops and the middle only in the video is that the person demonstrating it is using a bang-bang controller. It remains to be seen what the response of the servo motor will be to a PWM input from a train controller - whether its position will be proportional (either linear or logarithmic) to the duty cycle of the input.

At 23 seconds, evidence that the steering motor is the middle one. As the rear wheelset has tilted, its steering has been affected. This seems to be the only way to get different steering angles from the front and rear wheels as they are usually the same angle from straight.

At 27 seconds, see the 8M axles with cross blocks onto possibly the new 5-hole cross block that I assume connected to a short rack piece in the middle under the motor. See also the 12:20 gear ratio in the chassis. There is another 12:20 in the reduction hub, seen later.

It might be that the 12-tooth cog seen on the front has a 20-tooth cog beneath it. From there, there is either another 12-tooth cog under it, in which case no more reduction, or more likely a 12:20 ratio 2 studs further in, the other side of the light bley T-frame. It might be that the 20T cog of that interfaces directly with the 28T of the differential. Therefore there is one differential in each wheelset , and no centre one because the steering servo motor is there. The L-motor speed must be either 9/35 or 81/875 of the speed required for that size of wheel, with torque to match. Given that the name of the set is "Crawler" we should not expect it to break speed records, but the motor speed and torque combination looks encouraging nonetheless.

Regarding the servo motor, it would not be difficult to make it return to centre actively.

The PF system has a PWM signal on C1 and C2 and fresh power on 9V and 0V.

Therefore the servo motor could include a servo chip to take the PWM signal and set the motor current such that its servo position was in proportion to the PWM: positions of +/-1 to 7 or centred for zero (float and/or brake). The 9V and 0V pins would be used to send power to the servo chip (they are unconnected in the M and XL motors).

If it is done this way then the servo chip and motor would be all one piece as an off-the-shelf module. I would not expect an RTC module to be separate (like the hockey player block some of us have used with the M-motor). If it does include a servo chip on a PCB then that would be one reason why it is so large!

2 new motors and a new mounting block (on each L-motor). There is also a new type of cross block seen in the logging truck, which might also be used in the steering on the Crawler. Technic has a good run of new parts with the Unimog so I'm not surprised if there are fewer new parts this year.

Every other Technic vehicle seems to have a fake engine. I've lost count of the number of cylinders of fake engine I could build now! Fair to say that a truck of this size would find the cylinder size in better scale proportion though, as does the Unimog.

I hope TLG would release the L-motor and Servo motor as separate items in due course. I don't expect they would be available that way before January 2013. We should petition Jan Beyer and the other community support people for this. If the servo motor could do proportional position control then I would want quite a few. I would also like to see how the helicopter gets on with a couple of L-motors driving the rotor!

Mark

Edited by Mark Bellis

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@ Mark Bellis: Great analysis! I see what you're talking about in the

:

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Needs 10 more.

Oh yes, that would have been cool! 1337 ^^

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1327

Does anybody know the piece count for the helicopter?

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48 cm × 37,8 cm × 7,05 cm 1,171 kg and 1056 bricks anything more? :laugh: , everything is on technicbricks. Technic Gearhead was faster than me :thumbup: .

Edited by jorgeopesi

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If one could add four large "Power Puller" tires and wheels, the 9398 Crawler would look a lot more impressive. The 9398 is close in size to the 8297 Off Roader, and both use the same wheels and tires. Look at how this "Bigfoot" 8297 (from the Kocke Klub) looks with the Power Puller wheels, and imagine the same effect on the 9398 Crawler:

9398.jpg8297-1.jpg

cwetqo_2341_02.jpgcwetqo_2341_01.jpg

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b. i am sure the cost of development for the new motors took up the entire budget for new parts in this model.

d. once again i am sure that the motors were the priority, and other parts could not be added into the set without a significant price change.

e. this is only lego you know...

tim

b. and i am quite sure that the new motors are redundant. the money spent developing the motors would be better spent elsewhere, like making an rf receiver and transmitter.

d. like above, except worse, because realism is one of the three legs of the technic trifecta.

e. yeah, i know, but why did it have to be remote control out of the box, when it could have been a supercar with available remote control conversion?

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b. and i am quite sure that the new motors are redundant. the money spent developing the motors would be better spent elsewhere, like making an rf receiver and transmitter.

Well both Pneumatics and Train fans have been asking for servo motors capable of switching valves/points for a long time and something between the M and XL motors has also been requested a fair bit. And whilst there are a bunch of AFOL solutions for return to centre steering, they tend to use either rarer parts like the hockey spring and/or tend to put the motors under stresses that wouldn't pass TLG's standards. A proper solution for those will be really handy.

RF control might be nice, but I'm not sure it's as universally applicable. The vast majority of Lego creations probably work just as well with IR.

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Well both Pneumatics and Train fans have been asking for servo motors capable of switching valves/points for a long time and something between the M and XL motors has also been requested a fair bit. And whilst there are a bunch of AFOL solutions for return to centre steering, they tend to use either rarer parts like the hockey spring and/or tend to put the motors under stresses that wouldn't pass TLG's standards. A proper solution for those will be really handy.

RF control might be nice, but I'm not sure it's as universally applicable. The vast majority of Lego creations probably work just as well with IR.

I agree, it would be nice and most models would work just as well with IR, because both IR and RF would have limited range. At the end of the range the Crawler would stop with the steering straight because a lack of signal would lead to return-to-centre from the servo motor.

You're right about motor use - most AFOL mechanisms have stalled the motor at each end-stop. Those that don't, which use a white clutch cog, lose synchronisation between the motor and the mechanism, hindering return-to-centre as a command i.e. the centre position accuracy is at the mercy of the spring. I'm guessing the PF servo motor would include the whole servo circuit within the motor casing, hopefully enough to turn a PF PWM command into a servo position and compare that with the shaft rotary position (I do hope it's more than a 3-position servo). I wonder whether TLG have used a potentiometer, like in ordinary servos, a resolver (RVDT) or an encoder like the NXT motors.

I think RF (other than the existing system for LEGO RC cars) would cost more in development cost than these two motors, as well as in unit cost, and anything more than the existing RC system would be more hassle to TLG to meet all the FCC rules etc... for a multi-channel pack of parts like PF rather than the fixed protocol that a LEGO RC car has. We know what we're like - as soon as we had RF we would be asking for a 6-channel system for a helicopter :wink: Speaking of which there is an ideal vehicle for that in the forthcoming range...

The limited range of control for a 4x4 is the reason why the set has a bang-bang controller. If it had a train handset (and if the servo motor could do proportional control as we are hoping) then the IR Receiver would continue with each PWM speed command, changing only when it receives another. That would mean the Crawler could go out of range and still continue to operate - potentially dangerous if it is near a road with children or a dog chasing it. With bang-bang control the model will stop straight away if it goes out of IR range. Remember that (for the moment) the LEGO 4x4 is still a toy, not an RC scale model, so a short range is appropriate. We may wish for that boundary to be pushed back, but it would have to have too many metal parts to handle the stress and the 40-Amp motors and speed controller would get seriously hot (melting ABS), so it wouldn't be LEGO any more. I would like very much to make a LEGO model fly without helium assistance; if I ever succeed then a longer range with RF would be appropriate. For the time being I look forward to trying out the new servo motor. We couldn't use RF very well unless there were a servo to control!

Mark

Edited by Mark Bellis

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