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[help] Front axle for military truck.

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Hey guys! 

I'm working on a military truck:

1200px-Sisu_SA-150_military_truck_Jun200

But i'm kinda stuck with the axles because i'm terribad at making them. 

This is what i've built so far:
TXPz9qOl.png

It's the scale i'm going for. 

What i need is help with the 3 or 4 link attachment to the frame and steering mechanism. 
I will be using locked diffs in both front and rear and it will be in constant 4wd. It's meant to be offroad after all. 
Both servo attached to axle or servo in frame and using a linkage to steer is both okay as long as it works. 

If somebody can come up with this front axle, i can just copy it and modify so i'll have an axle for the rear as well. 

Can anyone help me with this? 

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Posted (edited)
1 hour ago, Mechbuilds said:

Hey guys! 

I'm working on a military truck:

1200px-Sisu_SA-150_military_truck_Jun200

But i'm kinda stuck with the axles because i'm terribad at making them. 

This is what i've built so far:
TXPz9qOl.png

It's the scale i'm going for. 

What i need is help with the 3 or 4 link attachment to the frame and steering mechanism. 
I will be using locked diffs in both front and rear and it will be in constant 4wd. It's meant to be offroad after all. 
Both servo attached to axle or servo in frame and using a linkage to steer is both okay as long as it works. 

If somebody can come up with this front axle, i can just copy it and modify so i'll have an axle for the rear as well. 

Can anyone help me with this? 

Hm...
You have a pretty good starting point (a rigid axle and wheel hubs with tons of connection possibilities) and you ask for help with with the simplest thing (attaching to the chassis, with which you even have a general good idea (3 or 4 link)) and another thing that you are on the right track with ("using linkage to steer". You can even go for Ackermann geometry pretty easily).

With what do you have problem actually? The frame itself and the drive? Because drive is the trickiest thing, not the others. I think it should be doable to come up with a solution without U-joints.

Sorry if I misunderstood the question.

Edited by Lipko

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@Lipko

The problem is i don't know how to attach it.. I'm trying to look at similar axles that use the H frame but all of those builds use the ball joint fork part to connect it. 
I don't want to use the ball join fork part because i want the H frame to be horizontal. Using the ball joint part it will tilt down on an angle. 



Well like i said, i'm really bad at designing axles.. This is what i could come up with:

WCcMeS0l.png

But i'm not really sure how sturdy this would be.. The moc itself would have lots of weight on it. That's why i geared the portal axles down so much. I'll probably use two XL motors and buwizz to power it.  But i can't really fit a servo on this.. So i guess it has to be mounted in the frame over the axle.. But i have no idea how to attach the axle to the servo in a way so when the suspension moves, the steering would stay relatively straight...

I think that linkage will probably not work.. 

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Posted (edited)

But why don't you use the pinholes in the H frame itself?

You could use the middle hole with a ball-pin pointing upwards to add a suspension arm (part with small ball socket on one end and axle holes on the other) and two sideways holes (just below the U-joints) for the links. The links and the arm is parallel and should be equally long, so you have a "horizontal" H frame.

The steering would go in front of the axle assembly. I don't understand why you are afraid of a linkage steering. Since it's not a trophy truck, it's not likely that the center of the axle will move too much vertically during operation. Just place the steering dragging link in a way that it'll be horizontal when the suspension is compressed under the weight of the vehicle. You have a pretty large space above the axle, so the attachment point of the dragging link onto the connecting rod between the wheels can be placed arbitrarily high to avoid any interference with other parts.

For the drive, dunno...

PS.: yes, your current linkage wouldn't work since it doesn't prevent sideways movement.

Edited by Lipko

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Posted (edited)

Oh you mean the @filsawgood's suzuki jimny type of deal with the servo and steering? Using that ball cup arm thing connected to the servo for steering.

I also was thinking about using the same type of mechanism that lego arocs uses with a linkage to the servo and mount the servo sideways  so the link moves front and back to steer left and right.. But i think that way would have interfered with the suspension.. 

@Lipkocan you whip up something on LDD to show me what you mean? 
I kinda liked using long track rods on the suspension so it looks more realistic.. But then again using a CV joint for drive only gives one stud of in and out movement.. 

Edited by Mechbuilds

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Just now, Mechbuilds said:

Oh you mean the @filsawgood's suzuki jimny type of deal with the servo and steering? Using that ball cup arm thing connected to the servo for steering.

I though you mean this by steering linkage in the first place...

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Just now, Lipko said:

I though you mean this by steering linkage in the first place...

Yeah i guess using a linkage is a better idea to have the axle look less cluttered. Servo sitting on top would make it very bulky. 

I also though how using the mercedes benz type of deal where the linkage moves front to back for steering. But then i'd have to mount the servo sideways. Not sure how it would interfere with the suspension linkages tho. 

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4 minutes ago, Mechbuilds said:

Oh you mean the @filsawgood's suzuki jimny type of deal with the servo and steering? Using that ball cup arm thing connected to the servo for steering.

I also was thinking about using the same type of mechanism that lego arocs uses with a linkage to the servo and mount the servo sideways  so the link moves front and back to steer left and right.. But i think that way would have interfered with the suspension.. 

@Lipkocan you whip up something on LDD to show me what you mean? 
I kinda liked using long track rods on the suspension so it looks more realistic.. But then again using a CV joint for drive only gives one stud of in and out movement.. 

I'm not following. Use long rods then. The suspension arm can be extended to any length. You have to make is sideways-sturdy anyways.

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Posted (edited)

Ehh.. I wish i had some reference to copy from. So far i haven't found any axles like this. Almost every one of the axles that use the H frame use the ball joint fork part. 

EDIT:
njtvvbyl.png
I guess this method would keep the H frame going up and down horizontally.. 
Ahh.. i'm so bad at making axles. 

Edited by Mechbuilds

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Posted (edited)

You are so overcomplicating it.

My wife's gonna kill me. I have so much work to do, yet I'm doing this. 
Anyhoo, just a very quick sketch without drive:
yxcyxcyxcxyc.jpg

Blue: suspension links
yellow: steering

Edited by Lipko

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I built it in real life. It does work as suspension geometry but the drive shaft is the next problem. Also the servo would interfere with that top ball joint cup part. 

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I built something that has a very similar axle layout.  Check it out for ideas on how to connect to the chassis.

 

 

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9 hours ago, Mechbuilds said:

I built it in real life. It does work as suspension geometry but the drive shaft is the next problem. Also the servo would interfere with that top ball joint cup part. 

Don't know about the driveshaft, but if I understood the problem correctly, you could move the steering link to the other side of the horizontal beam, so the servo would not collide with the ball joint.

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I like that axle andy posted. However i still want it to be servo steered. But it sure gives ideas.

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Posted (edited)

@filsawgood's rock rod front axle looks very promising. I wonder if it can be widened by 2 studs. 
I think i'll give it a shot and see how it works. 


EDIT:
After some tinkering, this is what i built!
 

 

Edited by Mechbuilds

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images?q=tbn:ANd9GcSBJfmfCPtuOf-Dxz-HbJY

Hmm.. I kinda want to preserve that distinctive long drive shaft that goes to the front axle. 
I need to rethink this.. 

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1 hour ago, Mechbuilds said:

images?q=tbn:ANd9GcSBJfmfCPtuOf-Dxz-HbJY

Hmm.. I kinda want to preserve that distinctive long drive shaft that goes to the front axle. 
I need to rethink this.. 

This clearly doesn't look like portal axles as the drive shaft is on the same height as the drive axles...

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4 minutes ago, Jundis said:

This clearly doesn't look like portal axles as the drive shaft is on the same height as the drive axles...

Guess it could be "inspired by".. Going with solid axles using legos would pretty much make the axle so low that it would drag dirt as it moves. 
So portal axles is a must.. 

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Here is my current progress: 

7vCcOzWl.jpg

The piece of chassis and springs are just a placeholder and not the finished thing. 

But yeah that's a finished rear axle. I will be having a short drive shaft for the rear and very long drive shaft going to the front like the SISU has in real life. 
I kinda don't want to have the drive shafts obstructed by suspension links. So i need to figure out a way to attach the axles from the top. 

Suggestions are welcome. 

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4RK9a2Yl.jpg

This is what i could come up with.. It works well going up and down and there were good bit of options how to attach it.. But when i want the axle to tilt side to side, it moves diagonally. 
It refuses to go properly sideways. It wants to tilt the other wheel backwards and other wheel forwards. 

Somebody said that it's very simple and easy because there are many mounting options but i can't figure out how. 

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Posted (edited)

LDD complete for both axles.. Still need a suspension.. 

Mcb8k6sl.png

EDIT: i might make the front drive shaft a couple of studs shorter for better steering radius.

Edited by Mechbuilds

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Update:

39Dqngtl.jpg

KdbVH6dl.jpg

Some progress has been made. This seems to work.. Now the issue is figuring out where can i attach springs.
Also there is no way to stop the axle from tilting forwards and backwards.. I wonder if i could attach a third ball cup beam part in the middle somehow.. 


Any tips or advice would be great. 

EDIT:
Added the third beam in the middle next to the tan gear.. Now just need to figure out the springs.. 

I'm still not completely satisfied on the solution because the ball cup beams are twisting sideways when the axle is twisted. 
I wonder if the same thing can be made with rods instead. But i might need a panhard rod to stabilize it from moving sideways. 

Edited by Mechbuilds

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Just try... and try again, and keep trying.... The best part of technic is trying and figuring it out. Someone else figuring it all out for you isn't really what its all about... 

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55 minutes ago, TeamThrifty said:

Just try... and try again, and keep trying.... The best part of technic is trying and figuring it out. Someone else figuring it all out for you isn't really what its all about... 

There is a point of time where you stop trying when you're getting nowhere.. 
I've built over 10 different systems and every one of them had issues and were not the thing i was looking for. 

So far i haven't seen any moc that was similar to this so i had no reference which to copy and modify from. 
If i figure a suspension to this then it would be pretty much one of a kind since every other moc either has a different axle altogether or the axle is slanted downwards. 
I want my axles to be vertical.. I'm just so tired of disassembling this over and over again and i'm not even getting close.. 


EDIT:
Since the previous image i posted, i've disassembled it and reassembled something other 3 times. And it's currently disassembled back to square one.. 

I might just give up and do this instead:
Trial Mongo Heist Truck – Nico71's Technic Creations
I just can't figure out a suspension that works. 

Edited by Mechbuilds

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I might've already shared this - can't remember, getting senile. It's loosely based on Nicjasno's Unimog axle. It can be easily adapted to work with portal axles and to match your desired track width.

800x600.jpg

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