Hey Guys

I've been working on a 4x4 with plow and a 4 speed box but im having trouble with the power functions and actually moving the vehicle. The 4 speed is geared super low to have torque to plow or rock crawl but it can still barely move in 1st and 2nd. the truck is pretty heavy and when the engines start to get enough torque to move it a set of gears starts to slip. i'm currently using to pf Xl motors to run the drive train both are newer versions. any solutions or ideas would be welcome and pictures soon to come.

Maybe you gear it down to much, also make sure the places where your gears mesh there is no slack.

Maybe do not gear it down so much. Or build a gearbox like Charbel's. He has both very low and very high speeds in his. It is also very compact. It would help if you provided a few pictures of what is built.

I'm trying to upload the pictures but the file size is to big I think it says I can only use 0.07mb of data to upload them and I can't figure out how to shrink them.

Sign up to BrickSAFE they are a good websight to share photos on and you can resize the images, or use Flickr

Ok thanks

fFrst couple photos. The first picture of gears are the two that slip the second is the central diff or transfer case and the third is a top view from the front at the drive motors and plow.

Why are the drive motors so far apart? How do they connect to the drivetrain? It is hard to tell from the photo, but is the 24 tooth gear in the pic above touching the dark grey beams on either side of the shift mechanism? This may be the problem, because if it cannot turn, it could cause the other gears to grind. Otherwise, everything seems fine to me...

The motors are connected through a chain of 16 tooth gears and the grey 24 tooth isn't rubbing, the shift lever is just an in out mechanism to have a rolling chassis or a driven one kind of like a clutch after the reduction gears from the engine.

I'm also using a 4 speed sequential box based off of Sheepos latest designs.

Which gears are grinding?

The two in the first photo whatever the medium tan bevel is and a 16 tooth connect the gearbox output to the transfer case input. they sit just behind the steering servo on the front axle and can be seen just above the ball joint in the picture of the front axle without its wheels.

That is huge! I didn't think it would be so big. The problem may be that the drive motors are to far away from the gearbox, and are not transferring enough torque to drive such a heavy model, thus causing the gears to grind. What are the final gear ratios in the model?

The model uses sheepos sequential four speed box and I'm not sure what the ratios are through that but the other axles are significantly geared down before they enter the box to what i thought was plenty of torque.

Sorry, this is a bit off-topic, but what set are those tires from?

37 minutes ago, nnamhcab said:

The model uses sheepos sequential four speed box and I'm not sure what the ratios are through that but the other axles are significantly geared down before they enter the box to what i thought was plenty of torque.

From your statement, the problem appears to be that you geared down the drive before it enters the gearbox. You should only gear the drive down after it comes out of the gearbox. This way, the motors have enough torque to drive the different speeds, then it is reduced afterwards to increase the torque. This fix may require a good bit of taking apart the model before it will work. But if you have enough parts, build a second gearbox and try the change there. If that works, then implement it into the actual model.

1 hour ago, BrickHat said:

Sorry, this is a bit off-topic, but what set are those tires from?

The tires are from the new Claas.

And to contribute to the actual discussion, I've never been a huge fan of gearboxes, but there are other mechanisms to have different speeds, not sure if they would help you, but you could look, and see if you like them. I find the friction to be the major issue with gearboxes. That's just my 2 cents though...

I'll try switching the gear reduction to the output side of the box instead thanks for the suggestion and gearboxes do present a good challenge to build, one with usable speeds, low friction, strength and reliability is really hard but the challenge is fun and if you can get it to work it makes the model a lot more fun I think.

1 hour ago, nnamhcab said:

I'll try switching the gear reduction to the output side of the box instead thanks for the suggestion and gearboxes do present a good challenge to build, one with usable speeds, low friction, strength and reliability is really hard but the challenge is fun and if you can get it to work it makes the model a lot more fun I think.

That is true, I just find from my own experiences that I don't really like gearboxes. To each their own

Is part of the problem that you are not using an "Official" gear pairing? I find that if the torque is a bit high anything that isn't a standard three hole gear pair tends to skip. The 16/20 tooth gears do go together as you have done, but imperfectly. 12/20 is the perfect match. In the real world, the centre distance of meshing gears are very tightly controlled, for good reason.

1 hour ago, Burko-uk said:

Is part of the problem that you are not using an "Official" gear pairing? I find that if the torque is a bit high anything that isn't a standard three hole gear pair tends to skip. The 16/20 tooth gears do go together as you have done, but imperfectly. 12/20 is the perfect match. In the real world, the centre distance of meshing gears are very tightly controlled, for good reason.

Yeah I had to move the drive axle over just one stud and was originally using two 8 tooth gears but they got destroyed by the torque output of the motors so i switched to the 16 and 20 tooth combo