Steering system for trailer

[olaf9198]

Hi guys

I post this here because it can be very usefull for small and medium trailer.

it isn't steerd by pf or pneumatics. Because of that u have more room for something else.

https://www.youtube.com/watch?v=cXCqbAk1fHM

(do you like my new way of recording?)

Feel free to post comment about it

[DLuders]

OK, but there is a lot of "tire scrubbing" going on, where the wheels are not rolling on the same radius. Trailers have to do something like this (with each axle's wheels turning on its own radius) via DIFFERENTIALS to prevent premature tire wear. Start at the 2-minute (2:00) part of this

; amimation by Blakbird :

Edited February 3, 2013 by DLuders

[olaf9198]

I know what you mean i need 2 think about that

[Johnny P]

i am also pretty sure that when you connect it to a rc truck you can not drive backwards with this way of steering .

the truck will push the rear trailer wheels in the other direction then you want to drive.

i just made a semi lowloader with six axxes that al steer with a different steering angle by using 1 servo motor.

i tried lots of different ways to steer the axxes but this was the only way it works proper when its loaded with a crane or something else.

grtz Johnny

[DLuders]

@ olaf9198: You may want to study the steered axle design on the Lego Technic 8053 Crane Truck (instructions available on this Brickset webpage). There are some good (oversized) pictures of the steering on Therion's Brickshelf Gallery.

[5150 Lego]

OK, but there is a lot of "tire scrubbing" going on, where the wheels are not rolling on the same radius. Trailers have to do something like this (with each axle's wheels turning on its own radius) via DIFFERENTIALS to prevent premature tire wear. Start at the 2-minute (2:00) part of this

; amimation by Blakbird :

I see what your saying in the drawing of the steering angles. In order to prevent premature tire wear and to get a controlled steering, you need each wheel to turn on a lightly different axis (which is illustrated very well in your drawing) but what does that have to do with the differentials? From my understanding he's not driving the axles on the trailer, but just steering them. Granted the system he is using doesn't address the angles of each wheel as it steers, but i have yet to see any lego set of mediem size that does. Usually its a matter of linkage to gain the correct, or close to correct steering angle of each individual wheel. Curious how a differential can be used to achieve this goal.

[olaf9198]

So DLuders am i getting u right?

U what that i steer more axle's so i don't have so many friction?

But this is based on a Nooteboom OSD semi low-loader and there aren't all wheels steered so i won't steer all wheels

I am working on a turning lock that if I drive backwards i don't get the wheels turned the wrong way

[DLuders]

I'm trying to learn more about that Nooteboom OSD semi low-loader trailer (since they don't have any of those in the USA):

[DLuders]

@ olaf9198: LaixEngineering has some good steering ideas shown on this Mini Mobile Crane webpage. Perhaps they could be adapted to your larger scale MOC (

) (Brickshelf gallery):

[jwiger]

A differential on a trailer axle is a waste of time. Typically trailer wheels are mounted on spindles or bearing similar to the front wheels of a rear wheel drive vehicle. These tires are scrubing because they are rotating on a comon axle shaft. Put them on individual shafts and you will not see this problem. There are several ways to handle heavy loads used here in the US. Most use fixed axles and simply live with the sliding of tires side to side as the trailer is turned. Typically on the highway the turns are gentle that the flex of the tire permits this with no bad effects. Turning tighter turns the sliding will be very noticeable. Some vehicles use axles like the ones you put on your trailer, they are some times refered to passive steer or drag axles. Trucks that deliever concrete often use these in the middle of the chassis and also at the back. In both cases the tires(axles) are lowered to drive on public roads to distribute the weight and not damage the road surface. When the vehicles need to make tight turns they are raised up to reduce turning resistance.

You may find it easier to use a system like this -with out trying to steer the axles.

[dr_spock]

You could have a mechanical linkage to connect the steering mechanism to the truck and use the angle of the trailer in relation to the truck to turn the wheels. I used something like that on my drawbar trailer. In real life they have 5th wheel sensors near the king pin in some trailers and that controlled the hydraulic steering. Some are controlled remotely by the driver in the truck cab. You could do a servo motor and IR receiver on the trailer setup.

[Johnny P]

when using an extra pf receiver to steer the wheels of the trailer you will also have to use a different channel than the one you use

for steering your truck because again you will not be able to drive backwards.

the best way(in my opinion) to steer the wheels of the trailer is linking them to the fifth wheel.

maybe in a smaller scale than 17.5 like my trailer you could use a mechanical way of linking them.

but in scale 17.5 it is not possible because there is to much slack in the connections you have to make.

and the trailer will never come back in line with the truck after cornering.

i used a pf switch and servo in my trailer.

i connected the switch to the fifth wheel and this way it always steers the trailer in the right direction.

fotos can be found by following this link.

grtz Johnny

http://www.brickshelf.com/cgi-bin/gallery.cgi?f=520119

fotos 38 and 41 show the simple system best.

[dhc6twinotter]

Great looking trailer Olaf9198! I like the different steering geometry you have on each of those rear axles.

OK, but there is a lot of "tire scrubbing" going on, where the wheels are not rolling on the same radius. Trailers have to do something like this (with each axle's wheels turning on its own radius) via DIFFERENTIALS to prevent premature tire wear. Start at the 2-minute (2:00) part of this

; amimation by Blakbird :

??? There's no need for a differential since this is a non-powered axle. Olaf9198's trailer allows each wheel to spin independently, which is perfectly fine.

That steering geometry chart you posted would probably be the most ideal steering setup, but the vast majority of trucks in the United States don't use steering geometry like that. The majority of semi trucks here have dual drive axles that don't steer and also have tandem, non steering axles on the trailer. In the northwest, it's pretty common to see trucks with 3 or 4 axles on the trailer, non of which steer. Many trucks in the NW also have additional self-steering lift axles on the truck and trailer.

In my area, many of the dump trucks and cement trucks use self-steering lift axles between the front steer axle and the dual drive axles. I've seen dump trucks with anywhere from 2-4 lift axles. From what I understand, these are not connected to the truck's steering, but steer themselves (like a grocery kart). The caster angle insures the wheels stay straight when the truck isn't turning.

[olaf9198]

DLUders I think he has locked the steering on that time because it's difficult to steer backwards with a steered trailer

when using an extra pf receiver to steer the wheels of the trailer you will also have to use a different channel than the one you use

for steering your truck because again you will not be able to drive backwards.

the best way(in my opinion) to steer the wheels of the trailer is linking them to the fifth wheel.

maybe in a smaller scale than 17.5 like my trailer you could use a mechanical way of linking them.

but in scale 17.5 it is not possible because there is to much slack in the connections you have to make.

and the trailer will never come back in line with the truck after cornering.

i used a pf switch and servo in my trailer.

i connected the switch to the fifth wheel and this way it always steers the trailer in the right direction.

fotos can be found by following this link.

grtz Johnny

http://www.brickshel...ry.cgi?f=520119

fotos 38 and 41 show the simple system best.

Hi it says that it isn't public yet maybe a deeplink?

You could have a mechanical linkage to connect the steering mechanism to the truck and use the angle of the trailer in relation to the truck to turn the wheels. I used something like that on my drawbar trailer. In real life they have 5th wheel sensors near the king pin in some trailers and that controlled the hydraulic steering. Some are controlled remotely by the driver in the truck cab. You could do a servo motor and IR receiver on the trailer setup.

But if u have a big load with many pf recievers that need 2 be on than u will have a bit of a problem because then the trailler will steer with it.

And it needs more space witch u don't have in a semi low-loader.

And I don't own a servo

Edited February 4, 2013 by olaf9198

[Johnny P]

more fotos will be public probably tommorow

i managed to fit in the trailer .

a servo for steering

and a medium + gearbox for function 1 : ramps on back off the trailer operated by 1 mini la.

function 2 : 2 mini la that acts like feet on the front off the trailer .

i used tesame wheels as you except my trailer is 13 studs wide between wheels.

Edited February 4, 2013 by Johnny P

[allanp]

@Olaf9198

I'm not sure how implementable it would be into your mechanism and scale but just for future refrence, in order to get the proper ackerman geometry as mentioned by DLuders you need to have the steering arms at an angle as shown here:

Some of the methods as described by dr-spock would be the best way to control the steering tho i'm not sure they wouldn't be too intrusive to your design at the scale you are building. As yours is now has the benifit of being one of the simplest and most compact solutions for very small scales. Thanks for posting.

Edited February 4, 2013 by allanp

[Samanen]

That looks pretty good. Great work!

[Pat-Ard]

Hi Johnny P,

that's really nice. The width would surely fit for the Unimog, don't ou think? I wouldn't build it with a fifth wheel hitch

More something like this...

http://www.baggerbetrieb-eichinger.de/wp-content/uploads/2008/10/dsc02142.jpg

Do you plan making a LDD?

Pat

[Johnny P]

hey Pat-ard

the total width is 19 studs. i dont own the unimog so i don't really know.

but for a unimog you may want to remove a few axles since it will have to be a drawbar trailer then.

and since my computer knowledge is nihil and posting pictures is al i can at the moment .making an ldd with not happen soon.

sorry for that.

[Pat-Ard]

Hey Johnny P,

the width would fit, the unimogs flatbed has the same width. Yes, I would build a trailer with a drawbar.

OK, no problem...

Pat

[olaf9198]

Hi Allan there is 1 problem because the gears cant handle a angle like this .

And i forgot 2 say that my trailer extends in length.

That looks pretty good. Great work!

thanks for this compliment.

Pat-Ard please discuss this with a PM.

[allanp]

Yeah, they would have to be linked via a linkage rather than gears and I wasn't sure if it would be all that easy or necesary at this scale anyway.