AndyCW

Lego King of the Hammers

25 posts in this topic

My newest project is inspired by the American King of the Hammers style of off road racing. It is not strictly crawling and is also not strictly desert racing a la the Baja 1000. The vehicles need to be dual purpose. They need to crawl over some pretty unpleasant obstacles and also go all out on open terrain. You can even overtake other competitors during the race. I think this style of Lego vehicle can combine all that has been learned about trial truck and crawlers and combine them. I was most inspired by the appearance of the vehicle at the 1:40 mark in the following video.

My KOH truck has the following

-2 RC buggy motors

-2 V2 IR receivers

-2 LiPo rechargeable batteries

-2 speed transmission from Sariel http://sariel.pl/201...utput-selector/

-Front and Rear Differential Locks from Sariel http://sariel.pl/201...ferential-lock/

-Auto valve inspired from TechnicBricks w/ onboard compressor

-RC4WD Rock Crusher H/T 1.9 tires

-Triangulated four links front and rear

-telescoping drive shafts

-9:1 axles

-PF Med steering 5:1 with 8t on rack and Ackerman geometry

I am currently mulling over Sariel's newer servo actuated three speed transmission. Initial tests showed that two RC Buggy motors had no trouble back driving the servo and so now I need to figure out how to overcome this shortcoming. The two speeds in the current transmission are not that far apart and with its weight the low gear was not low enough on some obstacles. These problems ought to be corrected by the update to a three speed, but it will take some more work to get there. I tried this transmission http://sariel.pl/201...linear-gearbox/ but the space between low and high was too great without a middle gear to bridge the spread.

I am not sold on the benefit versus cost analysis of the locking axles as opposed to axles that contain a spool.

I ended up compromising myself and breaking a cardinal rule of not altering parts. The front axle has a 2.5 stud axle and a 3.5 stud axle in it to achieve the track width I wanted. This could be alleviated if I had gone to a 2 stud wider front axle, but I didn't want to change the proportions that much.

I don't have many other relevant pictures yet, but I will provide what people ask for.

Comments, Questions, Concerns, or any advice is greatly appreciated.

v/r

Andy

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Perfect! ideal off roader with full package of functions that are remote contolled!

Do you have any problems with small 12 gears at differentials on high load?

More fotos and videos please!

P.s. Are that tires the same as Ansmann tires?

Edited by rm8

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To the best of my knowledge, the tires are very similar to the Ansman ones.

Pics will be forthcoming. In the meantime, what specifically would you like to see?

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To the best of my knowledge, the tires are very similar to the Ansman ones.

Pics will be forthcoming. In the meantime, what specifically would you like to see?

Bottom view, gearbox view, axles..:)

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Looks like a great off road truck! You have inspired me to reattempt my double rc motor truck.

tim

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The brown 12t gears in the axles so far have held together. I did have one of my old grey 12t spider gears shatter, but that was after there was some wheel hop trying to climb a carpeted obstacle in the house. The loss of all traction and then the sudden reaplication of that traction caused an "impact load" on the gear and it turned itself into a bunch of little pieces. Wheel hop is what usually break pieces during full scale off roading. I have pictures and will be uploding them shortly.

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Great looking crawler! I like the locking diffs and telescopic driveshafts. Nice overall design too. Well done. :thumbup:

I have some friends that run the Hammers on a regular bases. Several years ago, I had a chance to drive and ride along on some of the trails at the Hammers. Pretty insane trails with some very capable vehicles out there.

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Very cool and good looking King MOC, also all the futures you have bild in are great :thumbup::wub::thumbup:

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Just uploaded a large number of pictures to imageshack. Here are some highlights.

20121125151101813.jpg

Bottom view of front axle

20121125151252542.jpg

Top view of front axle w/ steering motor removed

The remainder of the pictures are available at http://imageshack.us/user/andycw

I used my cell phone camera. So..... the quality may not be the best.

Enjoy.

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Wow. Just wow. I've just made a xl motor per axle crawler that gets over just about anything, and a very small car with two buggy motors...will post when i get a new laptop... is that the new tan 4l axle from the 9398 in your portal axle? I've been using that technique to hold the 8t gear in place for a few weeks now...

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Nice MOC! I like those 3rd-party 1.9" I.D. RC tires on the Lego 44772 wheels. :thumbup: Did you get them at a local hobby shop in the USA? Any 1.9 tire in the 37mm-48mm widths will fit those Lego wheels.

Edited by DLuders

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Those are the newer tan axles in the portal hubs. This is my current technique to try to locate the 8t gear. The new 8t gear should make this solution even better or obsolete. I also use that part on the pinion shafts of the axles. The increased "bearing" surface hopefully helps.

The tires I got off of RC4WD's website. I was thinking about putting 2.2 tires on the 8448 wheels, because they have a better offset to work with portal hubs.

v/r

Andy

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20121124193117375.jpg20121124193154123.jpg

My newest project is inspired by the American King of the Hammers style of off road racing. It is not strictly crawling and is also not strictly desert racing a la the Baja 1000. The vehicles need to be dual purpose. They need to crawl over some pretty unpleasant obstacles and also go all out on open terrain. You can even overtake other competitors during the race. I think this style of Lego vehicle can combine all that has been learned about trial truck and crawlers and combine them. I was most inspired by the appearance of the vehicle at the 1:40 mark in the following video.

I am currently mulling over Sariel's newer servo actuated three speed transmission. Initial tests showed that two RC Buggy motors had no trouble back driving the servo and so now I need to figure out how to overcome this shortcoming. The two speeds in the current transmission are not that far apart and with its weight the low gear was not low enough on some obstacles. These problems ought to be corrected by the update to a three speed, but it will take some more work to get there. I tried this transmission http://sariel.pl/201...linear-gearbox/ but the space between low and high was too great without a middle gear to bridge the spread.

I am not sold on the benefit versus cost analysis of the locking axles as opposed to axles that contain a spool.

I ended up compromising myself and breaking a cardinal rule of not altering parts. The front axle has a 2.5 stud axle and a 3.5 stud axle in it to achieve the track width I wanted. This could be alleviated if I had gone to a 2 stud wider front axle, but I didn't want to change the proportions that much.

I don't have many other relevant pictures yet, but I will provide what people ask for.

Comments, Questions, Concerns, or any advice is greatly appreciated.

v/r

Andy

That is an amazing shock absorber setup along with the four link suspension. It is incredible to see some locking differentials on top as well. I have also been in the half a axle width as well. The differential valve lock looks strong have you experienced the clutch gear to pop out under some good amount of torque? Great Job On this crawler. Looks very tough and rugged.

Edited by Boxerlego

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Holy Necropost Batman!!!!

The locking differentials never popped or slipped out of lock. It does not take much pressure to keep a driving ring engaged. The front axle used a straight connector to engage the driving ring on the differential lock and the rear one used a shift fork. The front solution created a fair amount of friction on the axle with the driving ring on it. The locks only see 1/3 of the forces that the wheel experiences. I never had any problems with the differential locking mechanism other than the isolated mention above in post number 7.

I did have one of my shocks break at the top near the dogleg. I don't know how it happened. It could have been my little boy playing too rough with the truck. It was an easy fix. My son makes an excellent durability tester.

I have been using the same four link and shock setup on my projects since this and have not had any further troubles. The four link mounting points allow me to put in caster when I want.

Thanks for the interest and commendations. The follow up to this project is in the final testing phase. I moved to a four speed transmission.

v/r

Andrew

Edited by AndyCW

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Really well done! But do you really need diffs? I think normal locked axle would suffice. Also maybe use a 2 speed tranny, as 4 speed ones are less efficient.

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No differentials on v2. The cost vs. benefit is not good enough for me. Every two speed I have tried did not manage to utilize the full power of twin rc buggy motors. Either the spacing between the two gears was too little or too much. Three speeds would be better, but the only three speed I tried failed. I have success right now with running a normal driving ring four speed shifted by a pair of servo motors. The key is a strong structure around the gears, increasing gearing in the axles, and reducing the gearing going into the transmission. This reduces the torque that the driving rings in the transmission experience. The axles would also try to walk out of the gearbox. I had to use axles with stops and create the casing so that the axles were trapped.

A couple of non drivetrain parts are on order and I need to figure out how to make a better video. Hopefully between work, school, and family I will have the new project posted next week.

v/r

Andrew

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Because it is a crawler, i would suggest just to use a limited differential because it saves space is is very efficient.

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Because it is a crawler, i would suggest just to use a limited differential because it saves space is is very efficient.

By limited differential do you mean a limited slip , a locker, or a spool?

Most full scale crawlers have lockers, most performance cars have limited slips, most average cars have open differentials and crazy powerfull offroad vehicles (drag racers, hill climbers, pulling trucks, etc.) have spools.

http://en.wikipedia.org/wiki/Locking_differential

v/r

Andy

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By limited differential do you mean a limited slip , a locker, or a spool?

Most full scale crawlers have lockers, most performance cars have limited slips, most average cars have open differentials and crazy powerfull offroad vehicles (drag racers, hill climbers, pulling trucks, etc.) have spools.

http://en.wikipedia.org/wiki/Locking_differential

v/r

Andy

Limited slip, but i do not know mich about cars :blush:

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The motors sounded really fast towards the ending. Good inspiration for the gear switching and shock absorber!

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