The Enforcer Recharged: CUUSOO Project

[backbone]

Replace differentials with knobs, or break 12 teeth bevel gears and destroy diffs.

[rm8]

Obviously it looks impressive, and I'm sure that any technical issues can be resolved. I'm just wondering whether the TLC would be interested in doing yet another 4x4 RC off-road vehicle so soon after the original 4x4 Crawler and with the "Boss Crawler" already in the pipeline. Don't get me wrong though, I'd love to see this released. I think the "Boss Crawler" is a nice, stylish new body design for 9398 but this is every bit as stylish and with a different chassis design to boot.

New set is just a marketing campaign with main target- support main flagship product 9398. While new set will be limited with higher price, 9398 will stay unlimited (dont know how long) and cheaper. 9398 is balanced set with chassis and nothing more. What we get with Boss we will see at 22 of february...

About Enforcer:

Since crazy1993 give me right to write some constructive critics I will do it:

The main problem will be drivetrain:

1) it contain differentials - thats good for non-stress driving but dramatically for obstacles.

2) making enforcer without middle diff is dangerous for drivetrain. i have a MOC with 68's ballon wheels with AWD without middle diff and with axle diffs. Propulsion by 1 XL. The weight of model about 1 kg. Steering this car at flat surfaces is stressful for drivetrain. it is clearly visible at steering. Enforcer has weight 2 or 2,5 times more than my moc.

Only way to make such heavy moc drive and steer good - making different motors for each axle. Separate motors transmission simulate transmission with one motor with limited slip differential between axles.

Another reason why I dont like such transmission - XL motor. It gives much torque from output. This is good if wheel is connected directly to motor output or has minimum gears between wheel and motor. But in this situation motor gives huge torque thru all gears (with gearing down!!!). There is a huge risk that somewhere before wheel something brokes. If you lock the wheels by hand and push controller forward - something brokes. Of course 3 diffs save from that, but another side of this saving - bad crawling abilities.

The best transmission by Lego is to use fast and less torque motors (L, M) that cant broke gears in transmission (cause of small torque, they usually stall) and gearing down at final stage after all gearings and diffs - near each wheel. You know I am talking about wheel gear reduction, or unimog hubs.

I think thats one of the reasons why TLG develop and use L motors in 9398 instead of XL which is very dangerous in hands of unexperienced builders.

Hope you understand my idea - your transmission is loaded by high torque from the mototr output. Ideal chassis when drivetrain is loaded by high RPMs and low torque, and gearing down at final stage - near the wheels.

Thats no offence. I have bad experience with XL driving all wheels thru big drivetrain. Even if you can reinforce all gearing - gear will break:)

I have much to redesign in Boss with Technic designers before it will be final product. Boss is much simplier and based on "certified" chassis that was tested 7/24 then improved and tested again many times by lego before they present us 9398. All this test was real, not in LDD.

I dont wanna tell that your idea is fail, but i advice to find the way to test you chassis and made more research before CUUSOO.

As I sad we have much to improve in Boss - and that was only body. I cant imagine how it is hard to make chassis that will be accepted by TLG for particular set.

But whole idea of Enforcer is awesome, I agree and repect how you present it this time. Keep working on this project. Just more patience and hard work and you will hit the target;)

Edited February 13, 2013 by rm8

[TechnicMati]

Crazy_1993

All your efforts make that You really deserve to have The Enforcer put as an official Lego Set. So good luck on cuusoo and gathering votes. Hope that you're gonna get the required amount of votes. The Enforcer really deserves that. The whole modified chassis (nice idea of two shock absorbers per wheel) and several mods to the body make The Enforcer even more impressive. Well done!

Edited February 13, 2013 by TechnicMati

[1974]

I really don't see this as a CUUSOO project. Maybe you can sell the plans though .. but best to build one first

Not too fond of that switch arrangement. It'll wear out too fast

[crazy_1993]

@ crazy_1993: Don't be discouraged by the Lego Cuusoo prospects -- your model will gain EXTRA EXPOSURE there and possibly inspire others to delve into Lego Technic!

Agreed, I wouldn't have gone to the effort of the redesign or even making the thing in the first place if I just wanted to 'win' by getting my model produced. It's the process of building and developing the thing that is half the fun.

I really don't see this as a CUUSOO project. Maybe you can sell the plans though .. but best to build one first

Not too fond of that switch arrangement. It'll wear out too fast

Probably true but there is currently no other way I know of to make PF lights flash. It would be cool if lego released a little PF logic brick to pulse signals or introduce delays.

@ rm8, if you look at the motor stats table, my torque focussed gear arrangement gives the same wheel drive torque as the 9398 chassis. I was worried that more speed focussed gearing would overload the motor and cause PF overload protection to kick in. The total power output from the XL motor is actually much less than 2 L motors because the XL runs at a much lower RPM despite the torque increase.

[shadowhearth]

Have you actually built enforcer in or is it only lives on your HDD? I would much prefer to see it in real life. Something that looks cool in picture might not work properly or look that great in flesh.

[Meatman]

This is exactly what I thought would happen, I was originally going to have no centre differential but I researched this and apparently with 2 wheel steering, the front wheels are on different arcs to the back wheels so leaving it out would be bad for the transmission. This is not the case with 4 wheel steering like on the 9398 chassis.

Seriously, is everyone sure that removing the centre differential would not put strain too much strain on the transmission when steering? Removing it is dead easy to do so it doesn't really matter either way but it is good to get these things sorted out.

Yes it is just an LDD render because I have a nowhere near good enough LEGO collection to create something of this magnitude in real life, a CAD model gives me much more freedom.

Also. the Unimog model uses a centre differential which was one of my main reasons for including it.

I just used the LEGO to POV Ray converter and MANY hours of running POV Ray on my laptop to do all of this.

I am not saying not using the center differential, I am saying that you can't drive that center differential with an XL motor using a bevel gear. It is going to have all kinds of problems.

[crazy_1993]

I am not saying not using the center differential, I am saying that you can't drive that center differential with an XL motor using a bevel gear. It is going to have all kinds of problems.

I see your point, the geometry of where the centre diff can fit and the chassi makes it hard to avoid this but I shall see what I can do.

I also made sure that that bevel gear was VERY secure, but I do worry about the low area of contact of the teeth, they may break.

[Meatman]

I see your point, the geometry of where the centre diff can fit and the chassi makes it hard to avoid this but I shall see what I can do.

I also made sure that that bevel gear was VERY secure, but I do worry about the low area of contact of the teeth, they may break.

I am no MOC builder by any means, but if I were you, I would use the older style differential that the Unimog uses. You will get a better "Bite" than with the bevel gears.

[crazy_1993]

Here it is, an alternate centre diff design using no bevel gears to the XL motor. I tdoes reduce gear ratios by a factor of 5/7 though, making the drivetrain more geared for speed.

[Blakbird]

Here it is, an alternate centre diff design using no bevel gears to the XL motor. I tdoes reduce gear ratios by a factor of 5/7 though, making the drivetrain more geared for speed.

I think the gears that are likely to be the weak point in this setup are the 3 12 tooth bevels in the center differential. They have to carry the full torque of the XL motor with no reduction.

[Milan]

Here it is, an alternate centre diff design using no bevel gears to the XL motor. I tdoes reduce gear ratios by a factor of 5/7 though, making the drivetrain more geared for speed.

Not good, one gear inside the diff is going to brake.

Unless you put massive reduction stages after the diff, but the vehilce would be very slow and unusable.

[crazy_1993]

All gear reduction is done after the diff. From what I can remember of those diffs, they can take a fair bit of punishment due to the way the gears are locked in. I have never managed to break a LEGO gear in my life and I have done some ridiculous things with the gears in my childhood (I melted a motor in the process).

[Milan]

From what I can remember of those diffs, they can take a fair bit of punishment due to the way the gears are locked in. I have never managed to break a LEGO gear in my life and I have done some ridiculous things with the gears in my childhood (I melted a motor in the process).

I have broken quite a few gears inside the diff in a setup smilar to yours.

[Blakbird]

All gear reduction is done after the diff. From what I can remember of those diffs, they can take a fair bit of punishment due to the way the gears are locked in. I have never managed to break a LEGO gear in my life and I have done some ridiculous things with the gears in my childhood (I melted a motor in the process).

You should get in touch with the guys who do the truck trials in Europe. They have broken pretty much every type of gear and axle during their competitions. As far as I remember, the 12 tooth bevels inside the diffs are the most common point of failure. If you search for truck trials on this forum, you'll find a lot of information. Of course, for true off-roading you don't really want any differentials, but I think it is unrealistic to assume your Enforcer will be used in that way. It is not a trial truck. Indoors in common use the diffs are not a problem because traction is not a problem.

[crazy_1993]

The motor is geared down, meaning the combined output torque of the wheels is greater than the motor torque. This output torque per wheel is the same as on the 9398 chassis. Therefore the centre diff actually has to withstand slightly less torque than the front and rear diffs as it is before the gearing down. However when you factor in that 2 wheels are being driven from each end of the diff not one, slightly more strain is on it but not massively more.

The point is is that too many people assume that this model would be used to perform the first circumnavigation of the globe using a LEGO vehicle! In reality, all LEGO sets including the 9398 crawler specify that they should only be used indoors. The largest challenge the vehicle will face from the average user is probably a gravel driveway or flat grass.

[Brickend]

I don't think the problem is other people's assumptions: they are speaking from practical experience. Whereas this model has never turned a wheel in real life; I would counter that it is your assumptions that look dubious.

[rm8]

The motor is geared down, meaning the combined output torque of the wheels is greater than the motor torque. This output torque per wheel is the same as on the 9398 chassis. Therefore the centre diff actually has to withstand slightly less torque than the front and rear diffs as it is before the gearing down. However when you factor in that 2 wheels are being driven from each end of the diff not one, slightly more strain is on it but not massively more.

The point is is that too many people assume that this model would be used to perform the first circumnavigation of the globe using a LEGO vehicle! In reality, all LEGO sets including the 9398 crawler specify that they should only be used indoors. The largest challenge the vehicle will face from the average user is probably a gravel driveway or flat grass.

Difference is that 9398 uses two L and your MOc - one XL that is two times more torque from the shaft.

May be torque on wheel shafts is the same, but in the 9398 source of power is divided to two independent motors (2 times weak than xl) and stalling one axle do not boost torque on second axle. And enfrocer has 1 source of power with 2 times more torque. In theory differential must divide this huge torque 50/50 between axles. Stalling one axle makes boost of torque on other wheels. Problem is that diff with its weak 12t gears cant handle such torque management. Dont forget, that weight of model also do its "bad" part of work.

In 9398 torque is growing STEP BY STEP, and diffs get a little bit more torque than L motor shaft gives (12:20 gearing between them). After diff there are another two gearing stages (12:20 and again 12:20).

Your config: XL gives Lot of torque from the SHAFT (not step by step as L config). First who will cry from that torque will be tranaxle diff, then gearing down 12:20 - and axle diffs gets more torque than first diff. I am sure that if you hold all 4 wheels and push accelerator, 12t bevel gears in diffs will die/slip first. If you change XL to 1 L and do the same thing motor will stall and all gears will be alive and happy.

This all is theory, but people here have some experience in this. Hope it will help you to improve Enforcer. L per axle is best solution for Enforcer. You can use your modified chassis with 9398's axles and drivetrain, why not?

Edited February 14, 2013 by rm8

[GuiliuG]

12 sb gears won't break under Xl torque if they are not already fragilized.

[rm8]

12 sb gears won't break under Xl torque if they are not already fragilized.

Ok, break or slip.

[otpi]

Build your own diff using knob gears, a frame with the 40 t gear fixed. Takes up space, but should handle the torque.

[crazy_1993]

This all is theory, but people here have some experience in this. Hope it will help you to improve Enforcer. L per axle is best solution for Enforcer. You can use your modified chassis with 9398's axles and drivetrain, why not?

If I did that, I would basically have a 9398 chassis with a rechargeable battery box. This would break the rules of CUUSOO. Not only that, but in the 9398 arrangement, the battery box would have to be in the centre with no way to access the charging socket on the battery box. This would mean that I would have to go back to the old hinged body, adding a few hundred extra parts.

I think someone has to quantitatively test the maximum torque possible through a LEGO diff and make a video or something to entirely convince me.

All of this could be solved by removing the centre diff, but that could be even more dangerous while steering.

[rm8]

I think you should build your Enforcer around existing 9398 chassis with minor updates.

[crazy_1993]

Everyone CALM DOWN! I know exactly how to fix the problem, I just can't access LDD until I get home in 4 hours time. I can easily accommodate gearing to allow the centre differential to rotate at a much faster RPM with a lot less torque which will fix the problem. I just need to modify the gearing on both sides of the differential.

[Meatman]

It isn't a matter of just "Fixing a problem" you really should construct a physical model to make sure that there are not other issues with it. Afterall, this is a rather complex large model and it may work in LDD, but not properly in reality.