Flat baja-truck

[Lixander]

Just began another baja/ trophy-truck project, the other 2 (or 3) being ”canceled”.

I managed to put 2x L motors and 1x servo motor, both Power Functions; it also has positive caster-angle, independent suspension in front and solid axle suspension on the rear, (at least) semi-detachable body and the headlights can be be lit (there are 4 pin-holes for installing lights).

Heavily modified version of this

Edited August 1, 2023 by Lixander

[Lixander]

Worked on it; ready to be test-build........................sometime.

Also, this thing, if no problems appear, will reap - look at the gear ratios that I managed to put in it.

 

[gyenesvi]

Nice medium scale trophy truck with light-weight design (are those 81mm tires?), though I'm curious how much it will reap, that much of up-gearing looses quite some torque to move it, you have to calculate that in as well.. And the 8T gears might prove a bit weak for high power. Btw, why don't you lower that upper L motor by one stud to make it more compact and get rid of one of those 8T gears and align the 24T gears so that the 8T in the middle gets symmetric forces?

[Zerobricks]

Here are my tips:

• Since you increased wheel size, the original front suspension won't do. I recommend using some proper wheel hubs which will increase your wheel stability and the higher steering arm length will provide more accurate steering.
• As @gyenesvi mentioned, you can get rid of that 8 songle tooth gear for higher efficiency and compactness.
• I would also recommend using some wheel bearing hubs in the rar which will hold the wheels better at place.
• You might look into using the stronger, yellow differential to better deal with increaed load from the bigger wheels.

[Lixander]

9 hours ago, gyenesvi said:

Nice medium scale trophy truck with light-weight design (are those 81mm tires?)

Thanks! And yes, the tires are 81mm.

9 hours ago, gyenesvi said:

, though I'm curious how much it will reap, that much of up-gearing looses quite some torque to move it, you have to calculate that in as well

I don't know how to calculate the gear ratio for so many gears :/

9 hours ago, gyenesvi said:

And the 8T gears might prove a bit weak for high power. Btw, why don't you lower that upper L motor by one stud to make it more compact and get rid of one of those 8T gears and align the 24T gears so that the 8T in the middle gets symmetric forces?

If the motors run in the same direction, then lowering the motor and deleting a gear won't make it necessary to make a motor to run in the other direction than the other one?

9 hours ago, Zerobricks said:

Here are my tips:

• Since you increased wheel size, the original front suspension won't do. I recommend using some proper wheel hubs which will increase your wheel stability and the higher steering arm length will provide more accurate steering.
• As @gyenesvi mentioned, you can get rid of that 8 songle tooth gear for higher efficiency and compactness.
• I would also recommend using some wheel bearing hubs in the rar which will hold the wheels better at place.
• You might look into using the stronger, yellow differential to better deal with increaed load from the bigger wheels.

I will put some proper wheel hubs and potentially adding a differential. 

And there are Lego wheel hubs with bearings?

Thanks for the advices!

[gyenesvi]

2 hours ago, Lixander said:

I don't know how to calculate the gear ratio for so many gears :/

You don't actually need to calculate that, just know that up-gearing looses torque..

2 hours ago, Lixander said:

If the motors run in the same direction, then lowering the motor and deleting a gear won't make it necessary to make a motor to run in the other direction than the other one?

If the motors are running in the same direction, than you will actually HAVE to remove one gear to make it work. Currently the motors would need to run in opposite directions.

[Lixander]

30 minutes ago, gyenesvi said:

You don't actually need to calculate that, just know that up-gearing looses torque..

Oke...I know :))

30 minutes ago, gyenesvi said:

If the motors are running in the same direction, than you will actually HAVE to remove one gear to make it work. Currently the motors would need to run in opposite directions.

Oh..........I see. Thanks!

[Lixander]

I had some problems with the Studio - I keep getting the same Unity error screen that first freezes the program then closes it when the error screen progress is complete 

Despite that I managed to put proper wheel hubs on the rear and to modify the gear ratios and the number of gears with the motor height. I also tried to put on the front too, but I couldn`t found a solution for aligning the steering arms with the wheel hub because there is little to no space left.

Edited August 2, 2023 by Lixander

[1gor]

For front suspension ylu can perhaps use those steering arms:

https://www.bricklink.com/v2/catalog/catalogitem.page?P=15459&idColor=86#T=C&C=86

If there is no space for 5 studs; there is this steering hub:

https://www.bricklink.com/v2/catalog/catalogitem.page?P=32495c01&idColor=11#T=C&C=11

Perhaps you can use gears from this set

https://www.bricklink.com/catalogItemInv.asp?S=42140-1

to replace bevel gears.

[Lixander]

1 minute ago, 1gor said:

For front suspension ylu can perhaps use those steering arms:

https://www.bricklink.com/v2/catalog/catalogitem.page?P=15459&idColor=86#T=C&C=86

If there is no space for 5 studs; there is this steering hub:

https://www.bricklink.com/v2/catalog/catalogitem.page?P=32495c01&idColor=11#T=C&C=11

Perhaps you can use gears from this set

https://www.bricklink.com/catalogItemInv.asp?S=42140-1

to replace bevel gears.

I see. Thanks!

 

[Lixander]

I am not sure if this is going to work (the writing is made with a mouse, so don`t mind how terrible it is)

More refined version (down)

Edited August 2, 2023 by Lixander

[gyenesvi]

3 hours ago, Lixander said:

I am not sure if this is going to work

I don't think that would because the steering link has only one degree of freedom instead of the required two (it cannot turn horizontally).

Even if it would, the steering link would be shorter than the suspension link, which would cause toe in/out.

You should try to use a proper 6L link there, which would require redesigning the steering mechanism.

Edited August 2, 2023 by gyenesvi

[Lixander]

44 minutes ago, gyenesvi said:

I don't think that would because the steering link has only one degree of freedom instead of the required two (it cannot turn horizontally).

Even if it would, the steering link would be shorter than the suspension link, which would cause toe in/out.

You should try to use a proper 6L link there, which would require redesigning the steering mechanism.

I see and thanks for informing me.

By the way @gyenesvi ; putting the steering rack perpendicular with the gear will work?

Something like this: 

Edited August 2, 2023 by Lixander

[1gor]

Perhaps you could put gear rack above gear...

[Lixander]

Yeah, but I can't find anything to link the steering arms if I put it in the normal position.

I will try to fix the Studio tomorrow and make also a screenshot.

Edited August 2, 2023 by Lixander

[2GodBDGlory]

17 hours ago, Lixander said:

I don't know how to calculate the gear ratio for so many gears :/

Sariel's Gear Calculator app is a great tool for that!

[Lixander]

5 hours ago, 2GodBDGlory said:

Sariel's Gear Calculator app is a great tool for that!

Ok. Thanks!

[Lixander]

16 hours ago, gyenesvi said:

I don't think that would because the steering link has only one degree of freedom instead of the required two (it cannot turn horizontally).

Even if it would, the steering link would be shorter than the suspension link, which would cause toe in/out.

You should try to use a proper 6L link there, which would require redesigning the steering mechanism.

A new attempt, but still, I am not sure if the steering rack has enough ”freedom”.

 

Edited August 3, 2023 by Lixander

[gyenesvi]

1 hour ago, Lixander said:

A new attempt, but still, I am not sure if the steering rack has enough ”freedom”.

I think that's still not quite okay, maybe it will bend and stress the A-arm, and it may even pop apart easily. And yeah, working with that hub and the limited length of gear racks and links sucks..

[Lixander]

1 hour ago, gyenesvi said:

I think that's still not quite okay, maybe it will bend and stress the A-arm, and it may even pop apart easily. And yeah, working with that hub and the limited length of gear racks and links sucks..

I see.......and yeah, it sucks :/

[Lixander]

I think that this will be ok, even if the steering arms are 5L not 6L.

[Lixander]

Started test-building it; everything good except that the mid-frame was moving because it wasn`t anchored properly and a slight toe-out that increases when the suspension is under load.

[1gor]

Is there place to put 5 x7 frame in the middle to make it stronger (like rear chassis part in 42070 set)?

[Lixander]

58 minutes ago, 1gor said:

Is there place to put 5 x7 frame in the middle to make it stronger (like rear chassis part in 42070 set)?

Nope, there isn`t :/

The front is pretty secure though; it is just a little weak because the Technic curved 7x3 panel is not attached to the bottom, but it won`t come apart (so the steering rack is pretty safe).

 

Edited August 4, 2023 by Lixander

[Lixander]

I wondered if this solution will work; some small modifications and I managed to integrate this and I am impressed - the toe-out is gone, even if the suspension is under load or no; only that the steering arms are a little under tension. 

On 8/2/2023 at 5:39 PM, Lixander said:

I see and thanks for informing me.

By the way @gyenesvi ; putting the steering rack perpendicular with the gear will work?

Something like this: 

 

Edited August 5, 2023 by Lixander