4x4x4 steering doubts

[aol000xw]

Hello

I was trying things out and got a problem with steering. Before I try to rebuild it I want to be sure of what I am doing wrong and what I should try.

So think of a 9398 where the big ball joints are used for 4WD instead of steering. Then for the steering on each live axle I needed 1 CV joint and 1 universal joint (to link both steerings). The problem is that the steering has some very noticeable play to it due to the joints. Note that instead of rack and pinion the steering is based on a comb wheel with a ball joint and track rod, and its range is 45º rotation of the axle on either side. So it is a very sensitive setup. I still have to add some ¿geardown? between the comb axle and the CV joint so those 45º become 90º (so I can safely use the servo motor) that might halve the play from the joints on the wheels but add some from the gears.

Currently without making it entirely different I can only think of not linking both steering units (for using a single servo) and instead using an M motor with some gear reduction on each live axle both on the same channel of the IR receiver and getting rid of the joints alltogether. Any advice? I like the idea of the M Motors as in the end it will simplify things. Any drawbacks?

Mockup of the steering used.

[Alasdair Ryan]

What about ditching the servo and using a worm gear connected to a M motor,or using a LA?

Edited September 9, 2013 by Alasdair Ryan

[Tamas Juhasz]

I can only think of not linking both steering units (for using a single servo) and instead using an M motor with some gear reduction on each live axle both on the same channel of the IR receiver and getting rid of the joints alltogether. Any advice?

Don't use individual m motors in each axle. If they aren't connected mechanically, it can be easily that after a while the two axles will have different basic state in steering angles. For example the front wheels are paralell with the body, but the rear has 10° right.

Use two servos in each axles, that works.

[Zerobricks]

You are better off using individual steering servos than individual driving motors.

Edited September 9, 2013 by Zblj

[aol000xw]

Thanks guys, some ideas here I did not think of. Glad I asked

2 servos... or making it autocenter would work for the misalignment.

Worm with M gear might help keeping the comb wheel inplace. and the LA might replace it for a very fine tuned steering with an M motor. The sliding nature of the worm gear can make the connection between both axles way easier and I could use universal joints instead of CV joints.

I guess the first thing I must decide is If I use two motors or joints to connect both axles.

[MrNumbskull13]

I'm not sure how to answer your question but I have a question about 4x4x4 vehicles.

If you don't use diffs, is it easier to break u joints?

[Junpei]

Yes, it is definitely easier to break u-joint without diffs especially when turning.

You're talking about the steering motors on the axle right?

[Technyk32231]

Don't use individual m motors in each axle. If they aren't connected mechanically, it can be easily that after a while the two axles will have different basic state in steering angles. For example the front wheels are paralell with the body, but the rear has 10° right.

Use two servos in each axles, that works.

Or, you could have 2 independent steering motors, on two independent channels, and have independent 4 wheel steering.

[Junpei]

RC

Or, you could have 2 independent steering motors, on two independent channels, and have independent 4 wheel steering.

OK, try to fit that on a 9398. You know, there might be space in the body for steering motors, and transfer the steering through telescopic axles. Maybe an RC motor?

In the middle for the drive, and not the steering of course.

[Technyk32231]

RC

OK, try to fit that on a 9398. You know, there might be space in the body for steering motors, and transfer the steering through telescopic axles. Maybe an RC motor?

In the middle for the drive, and not the steering of course.

I know this is kind of a stretch, but you could mount the steering motors in the chassis and accomplish steering via a Pitman arm.