Compact mobile crane suspension

[shimon]

Hello everyone.

Im back with a new project, a modular mobile crane based on the Liebherr LTM 1090.

The main challenge was to make it all wheel drive+steering and suspension keeping it 17 studs wide max (otherwise the wheels would be out of proportion)

so using the new hubs was not an option and therefore i had to think of a way to deliever drive and steering while having a solid axle of 3L height.

after many attempts one of them gave me good results.

the hardest part was to make a platform for the rack but in this setup it is very solid.

the suspension setup would have 1 shock absorber for each pair of wheels (in a solid axle rotating around the drive axle 1 shock absorber is enough to be activated from both sides.)

Im not sure if ill be able to participate in the challenge since i lack the parts to make another pair so it depends if my order will arrive before the deadline.

this is a prototype version so it might be improved, it is just to show the idea.

the suspension setup will be shown later along with the chassis.

feel free to use and have a nice day!

Shimon.

Edited October 1, 2015 by shimon

[Milan]

Nice setup. Once i built LTM 1090, too, and had very similar setup.

Questions:

1. why dont you rotate the wheels by 180? That way hubs could go deeper into the wheels and will get pivot point closer to the center of the wheel.

2. For the contest...why dont you leave this setup for 4 back wheels, and just build simple non driven front setup, for 4 front wheels?

[shimon]

Nice setup. Once i built LTM 1090, too, and had very similar setup.

Questions:

1. why dont you rotate the wheels by 180? That way hubs could go deeper into the wheels and will get pivot point closer to the center of the wheel.

2. For the contest...why dont you leave this setup for 4 back wheels, and just build simple non driven front setup, for 4 front wheels?

First of all thanks.

Secondly, inverting the wheel will cause the tire to collide with the 1 x 2 beam when steered, even using the old wheel version.

id like to see your design, ive searched for similar setups and found none at that width with suspension+all wheel drive steer.

also placing the shock absorber takes a lot of space so that function modules need to be very compact

For the last question, that is a good idea, the perfectionism inside me didnt even let this thought come up.

[zux]

I wonder why 5x7 frames wasn't used here? You could have built more compact solution, while maintaining same properties.

Sadly, don't have any better picture, but it should be OK to understand what I came up with in my 17 stud width truck (click for higher resolution):

Wheels are attached with 87408, which allows to use other side of the wheel. And yes, front wheels are steered and driven, but should be fairly easy to adapt your suspension solution.

Edited October 1, 2015 by zux

[Kiwi_Builder]

Looks very good and similar to my axle design for the LTM 1070. Do you plan on having different steering locks for the axles or have them the same?

[shimon]

I wonder why 5x7 frames wasn't used here? You could have built more compact solution, while maintaining same properties.

Sadly, don't have any better picture, but it should be OK to understand what I came up with in my 17 stud width truck (click for higher resolution):

Wheels are attached with 87408, which allows to use other side of the wheel. And yes, front wheels are steered and driven, but should be fairly easy to adapt your suspension solution.

I thought of trying to fit a 5 x 7 frame but the connection to the triangle beam is very unpleasant because of the 1 stud gap but i might try that later on.

as for the rest of the setup, unfortunately i cant adapt your technique because the criteria of suspension at such size is to be max 1 stud above the wheel axle (yours is 2 studs) making rather bad ground clearance for utilizing suspension, also in order to pair another setup of wheels the center of steering needs to be as close as possible to the wheel so that the wheels wont collide,

and at last for the steering, the hardest thing is to maintain steering while the setup rotates aroun the driving axle, as far as ive researched the only possible way is with a 16 t gear

Ill try my best fitting the mechanism with a 5 x 7 frame, thanks for the tip!

Looks very good and similar to my axle design for the LTM 1070. Do you plan on having different steering locks for the axles or have them the same?

The triangle beams allow the half beam 1 x 2 at the same angle as the CV joint so its a natural limit the the steering angle,

as for the bottom rack holder, it is the best solution so far (in order for the rack to be held properly with the 16t there needs to be a half stud offset thus not being able to fall off

ill try to come up with a more esthetic way.

[TheItalianBrick]

Why don't you replace the shock absorber with pneumatic cylinders? It makes more sense for a crane! Also it will provide variable ground floor clearance like back in the day the Grove All terrain Crane had it!

[shimon]

Why don't you replace the shock absorber with pneumatic cylinders? It makes more sense for a crane! Also it will provide variable ground floor clearance like back in the day the Grove All terrain Crane had it!

it is not possible because the solid axle rotates around the driving axle

[TheItalianBrick]

You mean it's a pendular axle? You won't be able to vary the ground clearence but it's still cool to have pneumatic suspensions! You can also connect them with a hose inverting the outputs: lower output of the left pneumatic cylinder with the higher right cylinder!!

It will be like having a closed circuit!