Help with pitman arm steering and automatic clutch

[Dans lego]

Hello, I am currently building a realistic 4x4 chassis with leaf spring suspension and pitman arm steering setup.I am new to pitman arm steering and I would like to ask for some advice,tips or even examples on this steering type, The second thing I would like to ask is, does anyone have any ideas for an automatic clutch this is not necessary but I believe it would improve the performance and realism of the chassis, feel free to give your opinion as I will take every opinion into consideration

thanks in advance - Dan

[Blakbird]

A pitman arm is attached to the output spline a steering gearbox. The gearbox itself usually uses a ballscrew. Can't say I've ever seen that in Lego. However, the steering of some vehicles that use a link instead of a gear rack is similar in concept. 9392 is an example.

If you want better advice you should present some more information on your project. What scale is it? What kind of space do you have in the area? Maybe show us some pictures of you chassis.

[Dans lego]

A pitman arm is attached to the output spline a steering gearbox. The gearbox itself usually uses a ballscrew. Can't say I've ever seen that in Lego. However, the steering of some vehicles that use a link instead of a gear rack is similar in concept. 9392 is an example.

If you want better advice you should present some more information on your project. What scale is it? What kind of space do you have in the area? Maybe show us some pictures of you chassis.

Thankyou , I have a rather large amount of space to work with and I'm using the 8110

unimog wheels ,and I will have to try to get some pictures of the chassis ,

Edited December 20, 2013 by Dans lego

[nicjasno]

That steering box is called recirculating ball steering. The whole setup is flimsy in real life, let alone in lego....

Rack and pinion ftw :P

I tried something ike that in my charger, with a worm gear:

Edited December 20, 2013 by nicjasno

[Dans lego]

That steering box is called recirculating ball steering. The whole setup is flimsy in real life, let alone in lego....

Rack and pinion ftw :P

Thankyou Nicjasno , I have been admiring your work for some time now, do you think the "flimsiness" could be fixed somehow ? ,the only reason I am bothering with the pitman arm style is simply for realism as the chassis is for a Toyota landcruiser ute Edited December 20, 2013 by Dans lego

[Junpei]

How about jorgeopesi's automatic clutch? That's the most compact one I've seen.

[Dans lego]

How about jorgeopesi's automatic clutch? That's the most compact one I've seen.

Hello and thank-you , would you have a link or any pictures of it by any chance ?

[Tamas Juhasz]

How about jorgeopesi's automatic clutch? That's the most compact one I've seen.

If I remember well, it's a freewheel system, in one direction it allows torque to transmit, in other rotation direction isn't. An automatic clutch works like a car clutch, in both direction.

@Dans lego:

What type of automatic clutch do you think about? Like a real car clutch with friction discs, like a 16 tooth clucth gear (for example in Sheepo's Land Rover), or like a freewheel?

Clutch has many types.

Edited December 20, 2013 by Mbmc

[Dans lego]

If I remember well, it's a freewheel system, in one direction it allows torque to transmit, in other rotation direction isn't. An automatic clutch works like a car clutch, in both direction.

@Dans lego:

What type of automatic clutch do you think about? Like a real car clutch with friction discs, like a 16 tooth clucth gear (for example in Sheepo's Land Rover), or like a freewheel?

Clutch has many types.

I would prefer a friction clutch , although I could finish the model without the clutch I just believe it would add that slight bit of realism :P

[Tamas Juhasz]

There is two friction clutch I know about:

1. http://www.brickshelf.com/cgi-bin/gallery.cgi?f=532696

2. http://www.brickshelf.com/cgi-bin/gallery.cgi?i=5059300

[Dans lego]

There is two friction clutch I know about:

1. http://www.brickshel...ry.cgi?f=532696

2. http://www.brickshel...y.cgi?i=5059300

thank-you very much , but do you think there would be a way to turn any or them into automatic clutches A.K.A centrifugal clutches ? , maybe I should forget about the clutch idea :P

[DrJB]

Amazing MOC. I can't help but notice that the steering links are made-up of 'surgically altered' parts, retained by friction only ... not sure that's sufficient

Edited December 20, 2013 by DrJB

[nicjasno]

They're glued. Today i'd use 9L steering links.

The flimsyness can be fixed a bit, but it'll never reach the level of rack and pinion.

[Tamas Juhasz]

thank-you very much , but do you think there would be a way to turn any or them into automatic clutches A.K.A centrifugal clutches ? , maybe I should forget about the clutch idea :P

Even clutches are many times unnecessary, automatic clutch can be made from a normal clutch connected with the gearbox operating mechanism. When you shift gear, the clutch works (not easy to made). Friction disc clutches are big, I don't recommend you in a single 4x4 car. But the gear shifting would be better with clutch of course. Your choice, if you want a clutch, then add it. But when there isn't much torque in the drive chain, and you dont want to shift gear when there is load on the gearbox, then clutch doesn't add too much plus to your construction, "only" will be the car more realistic.

Centrifugal clutches need a LOT OF rpm. Even with buggy motor, you can produce a small amount of torque to transmit. It can be made with Lego technic, but a serious centrifugal clutch would be also pretty big. You have to stop the driving motor during gear change to have sence of the clutch. But maybe it's good for you, I never tried this type of clutch.

Edited December 20, 2013 by Mbmc

[weavil]

Here are my Pitman steering.

http://www.brickshelf.com/cgi-bin/gallery.cgi?i=5907663

http://www.brickshelf.com/cgi-bin/gallery.cgi?i=5907654

http://www.brickshelf.com/cgi-bin/gallery.cgi?i=5907645

[Dans lego]

Even clutches are many times unnecessary, automatic clutch can be made from a normal clutch connected with the gearbox operating mechanism. When you shift gear, the clutch works (not easy to made). Friction disc clutches are big, I don't recommend you in a single 4x4 car. But the gear shifting would be better with clutch of course. Your choice, if you want a clutch, then add it. But when there isn't much torque in the drive chain, and you dont want to shift gear when there is load on the gearbox, then clutch doesn't add too much plus to your construction, "only" will be the car more realistic.

Centrifugal clutches need a LOT OF rpm. Even with buggy motor, you can produce a small amount of torque to transmit. It can be made with Lego technic, but a serious centrifugal clutch would be also pretty big. You have to stop the driving motor during gear change to have sence of the clutch. But maybe it's good for you, I never tried this type of clutch.

Thanks , I think I will forget about the clutch it will be too much hassle just for a small bit of realism :)

They're glued. Today i'd use 9L steering links.

The flimsyness can be fixed a bit, but it'll never reach the level of rack and pinion.

thanks I have come up with a partial solution , I have decided to use a link connected to a 4 long ( x o o x ) piece which is connected to a few sets of gears , this has only partialy solved the problem though

[Rockbrick]

why not just a wormgear and a small cog?

or small linear actuator to move the linkage to the live axle

recirculating ball is more like a linear actuator - (making a geared down compact version of a worm drive in the same space... )

also there is the technic threaded axle (3737c01), you could make something slide up and down it (the bolts could be attached between 4 studs like the bushes can) with a balljoint on it and connect that to the

link arm to the steering. But that only appeared in 4 sets....

Edited December 20, 2013 by Rockbrick

[nicjasno]

The new worm gear found in the Construction crew set would be perfect for that, since it doesn't slide on axles. Combine it with a right sized gear and voila! :)

[Dans lego]

FANTASTIC idea guys , I'll have to see if I can purchase one or a set with one in it :D thanks heaps , well so far the chassis has

Front and rear lockable diffs

RC 3+R gearbox

Realistic leaf spring suspension with caster angle on the front axle

Now is there anything else any of you guys could suggest to add to the chassis ?

Edited December 20, 2013 by Dans lego

[Rockbrick]

anti roll bars....?

the pitman steering can also act like a panhard rod - or you can install it at right angles to the live axle like so:

Edited December 20, 2013 by Rockbrick

[Dans lego]

I don't believe this chassis should need anti-roll bars mainly because it is a 4x4 and that would take away from the total amount of flex

anti roll bars....?

the pitman steering can also act like a panhard rod - or you can install it at right angles to the live axle like so:

I have to admit .. I kinda wanna build a hotrod just to test that steering setup :P