Steered pendular suspension axle

[Fistach]

This is front steered pendular axle design designed to withstand heavy weights.

It is very compact - only 88 mm in width (without half-shafts). With 8421 wheels (or 8258 with half bush) you can make a front suspension only 104 mm wide (but you will have to change 5.5L axles to 3L with stop. WIth 8295 telehandler wheels I managed to make the width of only 160 mm!

Wheel angle is very big - I'm really happy about it.

I tested it and it still was working under the force of 5 kg! Although you will have to change long pins from without the friction to with friction for better stability.

Anothe pro is that pivot point is in the same plane as half-shafts thus allow making of a very good and simple propulsion axles (it's waiting until I get some time to publish it!) to fit exactly with the steered ones of my design.

It has the semi-Ackermann geometry. Although in the narrowest one you can' see it well but if you use longer beams for wider axles you will clearly see the difference. (By semi I mean that we only have a 9, 11 etc liftarms bu t - althoug I didn't calculate it - you would probably need e.g. the 8,73 studs long beam to make it perfect).

The axle was designed for veicles with more than opne steering axle. The pivot axle and turning axle are separate and this allows to make reduction / multiplications to get different wheel angles at different axles. You don't have to build separate reducers/multiplicators between the axles! If you plan to build a heavy vehicle with multiple steering axles you can add another motor and steer the axles from both sides.

The suspension is made only with regular technic parts.

Here are the instructions to build the suspension.

Critiques an dcomments encouraged. I hope you will find it useful.

Required parts:

IInstructions:

Instrukcja wraz z komentarzem.

It's better to slide the pins from top.

Axlepins are here to block the steering. If you want to reduce the wheel angles you can add a bush on the axle pins.

If you want to use 8421 or 8258 wheels you will have to redisgn this part. It's a piece of cake!

3L i 4L axles you need to slide from the side (sorry for this comment but maybe some newbies to Lego Technic will read this therefore I thought this note may be useful to them.

Instead of 7&9 liftarms you can use 9&11, 11&13 and 13&15 liftarms.

Put some thing liftarms at the top to finish it.

You can use all traditional gear ratios: 3:1 5:3 1:1 3:5 1:3.

happy building!

Edited April 8, 2010 by Intact

[DLuders]

Thanks for the detailed building instructions! I would imagine that folks will be using it to a create small truck chassis with multiple axles, similar to the #8421 Mobile Crane (pictured below). Each wheel has a different turning radius, so your design is very useful.

[maksavorst]

The steering doesn't work properly now does it?

[cbt]

The steering doesn't work properly now does it?

I could tell by the very first glance that the gear rack misaligns badly.

And heavy duty ?

A pendular and simple steering like the one on the #8284 Technic Tractor can definitely stand the test - and if it is too wide, then use 11L liftarms in stead of the original 13L liftarms.

And for further reinforcement you can secure the upper liftarm furher.

I could post some pictures of how I did it on my Technic Tractors, in case you a little need help in this matter

[Sergiu]

I could tell by the very first glance that the gear rack misaligns badly.

The misaligned rack is not a problem in real life, due to the fact that the rack doesn't have a very long travel and the gear has a big backlash, thus being able to mesh very well with the rack, despite the misalignment. I used a gear rack this way in my MOC and the steering worked flawlessly.

And heavy duty ?

A pendular and simple steering like the one on the #8284 Technic Tractor can definitely stand the test - and if it is too wide, then use 11L liftarms in stead of the original 13L liftarms.

And for further reinforcement you can secure the upper liftarm furher.

I could post some pictures of how I did it on my Technic Tractors, in case you a little need help in this matter

I agree, the tractor's front axle seems quite strong and well designed, but it may not be suitable for some MOCs, this one having a higher rotation point then Intact's one, so it's good to have more designs to choose from.