"Return to center" steering - question

[vladoniki]

Hi friends, I am going to make a return to center steering. Would you offer me a tested and good working return to center steering system? I would like to be simple, fast and easy steering, I want to use "Technic Gear 24 Tooth Clutch", not to harass and stop the motor.

Thanks to all!

[DLuders]

Here you go: http://technicbricks.blogspot.com/2009/09/...-to-center.html .

[Siegfried]

Here you go: http://technicbricks.blogspot.com/2009/09/...-to-center.html .

Now that is smart; I've always seen the hockey slap shot springs as being an under-appreciated part, but that's a great idea!

[vladoniki]

Good ideas, thanks! Do you think that this solution is healthy for the Lego motor? Is not it a great "power eater"? I mean when you don't use a clutch gear and the motor is powered, but it is blocked. I think if you use a clutch gear it will not steer.

[DLuders]

If you replace the 16-tooth gear with the 6542 16-Tooth Clutch Gear ( http://www.bricklink.com/catalogList.asp?q=clutch+gear ), it really doesn't matter that the Power Functions Medium motor will be working hard because the clutch will slip AFTER the wheels are in their fully-steered, extreme positions. See the pictures below -- just swap the gears. The motor won't really be in a "stalled" condition when the wheels are at "full lock" (turning left or right). Be assured that the car WILL steer just fine with the self-centering hockey spring and the 16-tooth clutch gear.

If you're really concerned about "Stalled Characteristics", read what "Philo" (Phillippe Hurbain) says about it 1/2 way down his webpage http://philohome.com/motors/motorcomp.htm .

Edited June 15, 2010 by dluders

[Sam42]

The 16t gear with clutch is totally different to the 24t clutch gear in function and application,

I don't understand how you could use one in the way you described dluders, without using an old style 1/2 bush to lock it to the axle, and what advantage it would offer over a regular 16t gear?

[allanp]

The 16t gear with clutch is totally different to the 24t clutch gear in function and application,

I don't understand how you could use one in the way you described dluders, without using an old style 1/2 bush to lock it to the axle, and what advantage it would offer over a regular 16t gear?

I agree. Besides even if it did work like the 24 tooth clutch gear the return to centre spring would stall the motor anyway.

I think what you really need is a way to cut the power off from the motor when full lock is achived (perhaps using a PF pole reverser switch operated via a crank on the pinion shaft). This would prevent damage to the motor, wear on clutch parts and prolong battery life. But then you have the problem of the spring trying to return the steering back to centre as soon as full lock is achived. I haven't really looked into it much yet, I did start working on a pneumatic solution to the problem (pneumatic power steering) but got distracted! I'll let ya know if I finish it. I'm not really happy with having to keep power to the motor in order to keep it at full lock, and only having the power of the return to centre spring to bring the whole mechanism back to centre as it's not ideal on larger MOCs.

[DLuders]

In the "Comments" section at the bottom of the TechnicBRICKS Blogspot post referenced above ( http://technicbricks.blogspot.com/2009/09/tbs-techtips-26-return-to-center.html ), Jetro pointed out another possible "Return to Center" steering solution developed by Sheepo at http://www.brickshelf.com/cgi-bin/gallery.cgi?f=361332 . Jetro wrote,

"There are several advantages. For starters, Sheepo's solution uses more common parts. Also, the friction that the spring part in the first solution provides is very high and as a consequence requires a lot of effort from the motor whereas Sheepo's solution has less friction. You can regulate the necessary force by adjusting the rubber bands (or using different ones) which means you can adapt it to the motor you use and the direction system you have."

[Surly]

Not really an answer but the lego steering systems I have seen do not incorporate the normal methods vehicles use to self centre the steering being castor, kingpin inclination and to some degree toe in.

I am not sure how you could implement all of them but castor could be included by using a turntable to mount the kingpin and turning the outer race one or two teeth. I am not sure if this would generate sufficent force to float a steering motor back to centre though.

Just thinking out loud really

cheers

Surly

ps as this is my first post I must say I am in awe of some of the MOC's and skills members here display.

Edited June 22, 2010 by Surly

[Jetro]

In the "Comments" section at the bottom of the TechnicBRICKS Blogspot post referenced above [...] Jetro wrote,

I really like Sheepo's solution, but you may also want to have a look at Mahjqa's Basic and Intermediate Power Functions Chassis which use shock absorbers for the same purpose: