Gear Grinding/Clicking Issue In Gearbox (EV3)

[StudRobotics]

I'm building a SUV drivetrain for my Lexus GX EV3 project that has independent suspension, four-wheel-drive, and a four-speed gearbox with a medium EV3 motor that shifts the gears. Unfortunately, after testing the drivetrain, I found that when in 3rd or 4th gear, the gears make a clicking noise when moving forward and then straight to backward. However, this clicking somewhat occurs less when going from reverse to forward. This clicking really "grinds my gears" and I don't know what to do to stop the gears from clicking. My gearbox is a custom version of Sariel's four-speed sequential that is fit for the vehicle I am building. The input in the transmission is switched to provide more speed. Two large EV3 motors drive the input. I've noticed that when the vehicle stops, it goes the opposite direction for a little bit. Also, like I already said, this clicking only happens in 3rd or 4th gear, but mostly the 4th gear since it brings the most speed. I tried to solve this clicking with different gears and whatnot, but no matter what they still clicked when the vehicle moved forward to backward. The motors and the gearing also bring a lot of torque as much as it brings speed, and this might be one of the problems. Is there any way I can solve this issue so the gear clicking will stop in this situation (moving foward and then straight to backward) for now on?

Here's a photo of the bottom of the drivetrain.

Thank you in advance for any assistance that you may be able to provide!

Edited March 22, 2017 by StudRobotics

[aeh5040]

It's very hard to tell what the issues might be from one small picture, but it looks as if you have the 24t white clutch gear and the light bluish gray axle connector fouling each other at the extreme right of the picture.  If they are at 2 stud spacing, they will contact.  A bush instead of the connector will not.

[Didumos69]

36 minutes ago, aeh5040 said:

It's very hard to tell what the issues might be from one small picture, but it looks as if you have the 24t white clutch gear and the light bluish gray axle connector fouling each other at the extreme right of the picture.  If they are at 2 stud spacing, they will contact.  A bush instead of the connector will not.

I can confirm this. Apart from that I think the issue is simply caused by switching from forward to backward (and vice versa) at speed. The kinetic energy of your car will work against the motor right after switching directions. That will cause wind-up in your drive-train, which also explains why the vehicle moves a little in the opposite direction after stopping. Btw, the white clutch gear is supposed to slip and grind in these kind of situations.

Perhaps you should only switch directions at low speed in first gear or stop before you switch, just like you would in a normal car.

Edited March 22, 2017 by Didumos69

[TheMindGarage]

Try gearing up before the gearbox and down again afterwards. Reduces efficiency a little, but will reduce the amount of torque the gearbox has to deal with considerably.

Also, I see you've also migrated from the Message Boards :D

[aeh5040]

On 3/21/2017 at 11:52 PM, Didumos69 said:

Btw, the white clutch gear is supposed to slip and grind in these kind of situations.

Slip, yes.  Grind, no!   

Edited March 24, 2017 by aeh5040

[StudRobotics]

I really appreciate the responses, but my gearbox is still a mess. I don't know where exactly the clicking gears are. BTW the white clutch gear I didn't use it for the gearbox, I used it for the steering system so I can turn the wheels without moving the motor. I actually did put a white clutch gear at the end of the gearbox once, but the car didn't move at all because of the massive torque. Here's what I know. The gears click when going backwards at either 3rd or 4th gear (I don't know what gear is which, sorry). I can hold the car down and stop it from moving in this gear and when going in reverse the motors still move while the car is still, but when going foward, the motors stop (I avoided doing this again to prevent a motor stall) because the power managed to reach both differentials in the four-wheel-drive. I also found out something new after replacing the black gears at the end with more speedier gray ones. In either 3rd or 4th gear, there is so much grinding that the car can't move very much at all with the high torque the motors produce as well as the high gear ratio it has. I concluded that for the fourth time I absolutely have to completely rebuild my gearbox, after Sariel's 4-speed sequential ultimately failed on me. It would be a relief if any one of you could bring me a .LDD file or something of a working 4-speed sequential gearbox that can shift gears with a motor while the car is moving. I want this gearbox to make the car go pretty fast at last gear, but really torque-y at first gear for climbing hills. It needs to also have a white clutch gear that prevents clicking/grinding and so the motors can still move the car while another motor shifts the gears (by using an EV3 program where pressing a button switches to the next gear). If you have the time to create a gearbox like this in Lego Digital Designer for me, I would be very happy and excited to try it.

 

Here's some pictures of the entire drivetrain. I'm sorry if it's too faded, I had to keep it under 40 kb.

[M_longer]

3 minutes ago, StudRobotics said:

Here's some pictures of the entire drivetrain. I'm sorry if it's too faded, I had to keep it under 40 kb

No, you could just use Bricksafe. Or Flickr. Or any other image hosting.

[aeh5040]

Whatever the white clutch gear is used for, it is fouling the connector, which seems to be part of the drive train. You will definitely have grinding until you fix that (and it is very easy to do).

[StudRobotics]

@aeh5040 Like I said, the white clutch gear isn't touching the connector. I'll post some better pictures soon, but right now I'm just asking for a better gearbox since Sariel's doesn't really work for me.