[MOC] Remote controlled 4-speed AWD gearbox

[harriedegroot]

A compact sequential heavy-duty 4 speed remote controlled AWD gearbox

Each gear of this remote controlled gearbox approximately doubles the speed of the previous.
The output shaft contains an integrated lockable differential for AWD.

See the video for a WORKING DEMO | FREE INSTRUCTIONS below.

 

GEAR RATIOS

1st       6:1
2nd   3.3:1
3rd    1.8:1
4th       1:1

FEATURES

• compact

• remote controllable

• sequential gearbox

• 4 transmission speeds

• evenly distributed gear ratios

• differential output (AWD)

• differential lock

• single rotary catch

• many mounting points

• no half studs

INSTRUCTIONS

[PDF] https://bricksafe.com/files/hdegroot/remote-controlled-4-speed-awd-gearbox---with-perfect-gear-ratios/remote-controlled-4speed-awd-gearbox-with-differential-lock.pdf

[3D MODEL] https://bricksafe.com/files/hdegroot/remote-controlled-4-speed-awd-gearbox---with-perfect-gear-ratios/remote-controlled-4speed-awd-gearbox-with-differential-lock.io

REBRICKABLE: https://rebrickable.com/mocs/MOC-83457/hdegroot/remote-controlled-4-speed-awd-gearbox-with-perfect-gear-ratios

BRICKLINK: https://www.bricklink.com/v3/studio/design.page?idModel=244834

Edited August 2, 2021 by harriedegroot

[Bartybum]

Looks good, but is it a good idea to have the 8z gear driving the differential? Aren't they generally pretty soft and fragile?

[suffocation]

28 minutes ago, Bartybum said:

is it a good idea to have the 8z gear driving the differential?

 

[Bartybum]

@suffocation You'll have to forgive me, but my brain is too smooth to understand. Do you mean the 8z gears in each portal axle?

Edited August 2, 2021 by Bartybum

[harriedegroot]

1 hour ago, Bartybum said:

Looks good, but is it a good idea to have the 8z gear driving the differential? Aren't they generally pretty soft and fragile?

Dunno, I'm just a beginner standing on the shoulders of some gaints here on the forum!

This was the only option I could fit the gearbox into the 5x7 frame with the wanted gear ratios.

Edited August 2, 2021 by harriedegroot

[suffocation]

2 hours ago, Bartybum said:

@suffocation You'll have to forgive me, but my brain is too smooth to understand. Do you mean the 8z gears in each portal axle?

You can see the drivetrain for axles 3 & 4 - two hard-coupled XLs driving an 8z, which in turn drives a 24z going to the two rear axles.

To be fair, the assembly is designed so that the 8z can be easily replaced.

[Zerobricks]

While it looks good in theory the differential is lacking support and where the 8 tooth gear and diff meet is a weak point which will slip at any higher torque. Did you try blocking the diff?

[harriedegroot]

When the differential is locked, it gains some additional stability. Actually more than I expected on beforehand.

1 hour ago, Zerobricks said:

While it looks good in theory the differential is lacking support and where the 8 tooth gear and diff meet is a weak point which will slip at any higher torque. Did you try blocking the diff?

I did block the output until the input motor fully stops, this can be seen from 1:03 in the video.

But you're correct, I wouldn't count on high torque put to the 8z/diff without the lock in place (that's 2 out of 8 configurations), that's indeed the weakest spot.

Finally, as a trade-off, you can also leave-out the differential lock and fully support the diff itself to overcome this weakness.

Edited August 2, 2021 by harriedegroot

[harriedegroot]

Forgot to say I really appreciate the feedback! It also reflects some of the design choices made to keep the build as small as possible, without loosing functionality and without compromising on the gear ratios.

[Bartybum]

8 hours ago, suffocation said:

You can see the drivetrain for axles 3 & 4 - two hard-coupled XLs driving an 8z, which in turn drives a 24z going to the two rear axles.

Ah I see, ty!

5 hours ago, harriedegroot said:

Forgot to say I really appreciate the feedback! It also reflects some of the design choices made to keep the build as small as possible, without loosing functionality and without compromising on the gear ratios.

No problemo, it’s always nice to see people designing gearboxes

[Mr Jos]

Nice design, and great video design. I liked the starting part where it rotates around, I could pause the video everywhere to see what you've done!

About the 8T gears, I think they can handle pretty much. Certainly the power from 1 motor. In my designs with heavy torque I used 8z gears and they did not deform yet, but I have a lot of twisted axles already. (Yesterday have thrown away 8more).

Nice way to start here 

Edited August 3, 2021 by Mr Jos