Help with pendular suspension needed

[Junpei]

I am pretty new to technic, and I would like to build a rock crawler, but I am not sure how pendular suspension works. I can see it has one pivot point on the axle and two on the frame, but shouldn't that still stretch the shock absorbers when it tilts? So yeah, I am not sure what to do, so if anyone could give me some pointers for just a generic pendular suspension, that would be great.

Edited May 27, 2013 by TwentyLeggedHen

[Someonenamedjon]

Pendular is at the end

http://m.youtube.com/#/watch?v=QpXZJbU6V3U&desktop_uri=%2Fwatch%3Fv%3DQpXZJbU6V3U

[DLuders]

In this Eurobricks topic about "George Staples' Lego Technic Suspension Tutorial", he wrote this:

"2) PENDULAR: The pendular suspension is another very simple design. It's basic idea is wheels on the sides, and a pivot point in the center of the axle.

Pros: Has the best travel(distance from lowest point of suspension to highest; Simple to build; Good for small MOCs; Steering can be attached easily, and steering shaft can be the pivot shaft.

Cons: No "squish" in suspension; When one wheel moves up, it tilts the wheel onto it's edge; If equipped on front and rear, cab of vehicle tips over.

My suggestions for using this suspension are: use this mainly for front axles, If used for rear and front axles rubber bands must be used to level....The main problem with the rubber bands is that it's hard to get the cab level, and keep it level...."

[AndyCW]

The shock absorbers are usually not attached to pendular axles. They are only attached to the chassis. You can look up pendular axles on youtube and see many lego solutions.

Some pendular suspensions don't use shocks at all and just connect the corners of the vehicle with a gear train or links to facilitate articulation.

v/r

Andy

[Junpei]

Sorry, I meant the pendular suspension in 9398 that can also have the whole frame pushed downward over the axle. Sorry if this is unclear.

[Nazgarot]

Sorry, I meant the pendular suspension in 9398 that can also have the whole frame pushed downward over the axle. Sorry if this is unclear.

That's not a pendular suspension, but a live axle. if you search a bit on this forum you will see there is several topics discussing live axles for crawlers. Search for crawler or live axle.

-ED-

Edit: The axles in the crawler and the Unimog are live axles utilizing torque tubes. There are also other types of live axle, for example a 4 link system.

Edited May 27, 2013 by Nazgarot

[Junpei]

Ok thanks Nazgarot! I was kind of thinking that too but wasn't sure.

[aqaz]

There is an excellent chapter in: 'THE UNOFFICIAL LEGO® TECHNIC BUILDER’S GUIDE', by: Paweł “Sariel” Kmiec.

Chapter 15 should give you a good understanding of not only pendular suspension but how and when it is a suitable solution. Avoiding anything quite as silly as: 'If equipped on front and rear, cab of vehicle tips over.' (posted above by Dluders)