[WIP] Heavy Duty Skid-steer Loader

[JLiu15]

Hey guys, here's a new MOC I'm working on. This MOC will be an experiment in combining the new Mindstorms with Control+ to control 6 motors with a single hub. It will be powered and controlled by the new Mindstorms hub, with 4 angular motors for drive (1 per wheel) and Control+ motors for elevation and tilting. With the new Mindstorms having much better form factor than EV3, I anticipate it being much easier to use in my MOCs than EV3. The loader is inspired by the CASE SV340 skid-steer loader. However, some parts of that vehicle, especially the rounded section of the arms towards the rear, will be difficult to model with Lego pieces, so I won't model this after any specific skid-steer loader.

So far, I have the chassis built. It's a compact chassis made of 4 angular motors sandwiched between two 11x15 frames. The wheels are driven through planetary hubs, giving it lots of torque. This gives me a good starting point to attach other elements, such as the arm mechanisms and the Mindstorms hub. This will definitely be an interesting build. When I learned that the new Mindstorms is cross-compatible with C+ thanks to both being in the Powered Up ecosystem, I knew I just had to make a MOC combining them. If all goes well, I'll definitely be experimenting more with the new Mindstorms in the future.

If you have any suggestions for me, please let me know.

Photos:

Edited January 28, 2022 by JLiu15

[JintaiZ]

I think the wheels are a bit close to each other (even though it's the way loaders are supposed to look like) but otherwise it's a great start!

[JLiu15]

10 hours ago, JintaiZ said:

I think the wheels are a bit close to each other (even though it's the way loaders are supposed to look like) but otherwise it's a great start!

Thanks! As for the wheels, they're normally pretty close together on a real skid-steer loader.

[SNIPE]

nice work with the motors and wheel hubs.

looks like a rollcage car

Edited December 28, 2020 by SNIPE

[JLiu15]

4 hours ago, SNIPE said:

nice work with the motors and wheel hubs.

looks like a rollcage car

Thanks! Lmao it does kinda look like one at the moment 

[trekman]

That is going to be a serious skidsteer.  I would point out that balance is everthing in this, you need to have weight to the back unloaded and weight to the front when loaded, so your battery box position will be important.  Otherwise you will have limited fun in manouvering.

[JLiu15]

8 hours ago, trekman said:

That is going to be a serious skidsteer.  I would point out that balance is everthing in this, you need to have weight to the back unloaded and weight to the front when loaded, so your battery box position will be important.  Otherwise you will have limited fun in manouvering.

Good to know. Where would you recommend me place the battery box (or in this case, the hub) here? I plan on placing it in the rear so that it can act as a counterweight. However, the new Mindstorms hub is very light so it shouldn't affect the center of gravity all that much. I could also try placing it horizontally right above the chassis, but then accessing the buttons on the hub could be difficult.

[pdw]

Following this with interest.  My Christmas present to my daughter was a wheeled skid-steer MOC, and it's a really fun little model.  I echo what's been said above about weight distribution.  My design had all four motors behind the rear axle (PF, 2 x L, 2 x M) and the battery box (6 x AA) between the wheels and it was a bit too keen on wheelies.  Managed to shuffle the battery a stud further forward and the handling is now pretty good, although it's much slower to turn when it's loaded and the weight is evenly over both axles.

I think what you've got is a great start.  Four motors should give you plenty of power for turning, and nice low central weight.  I'm not familiar with the hub, but I suspect you'll get away with putting it behind the rear axle, especially if you can keep it low.

 

[JLiu15]

5 hours ago, pdw said:

Following this with interest.  My Christmas present to my daughter was a wheeled skid-steer MOC, and it's a really fun little model.  I echo what's been said above about weight distribution.  My design had all four motors behind the rear axle (PF, 2 x L, 2 x M) and the battery box (6 x AA) between the wheels and it was a bit too keen on wheelies.  Managed to shuffle the battery a stud further forward and the handling is now pretty good, although it's much slower to turn when it's loaded and the weight is evenly over both axles.

I think what you've got is a great start.  Four motors should give you plenty of power for turning, and nice low central weight.  I'm not familiar with the hub, but I suspect you'll get away with putting it behind the rear axle, especially if you can keep it low.

 

Just wondering, since you said yours had 2 PF L and 2 PF M, how did you drive the wheels? Did you just use a system of gears? I was hesitant to use gears for such a drive system as with so many gears they're all gonna be stressed a lot, especially when turning.

Also do you have pics of your skid-steer MOC?

[pdw]

Yes, two driveshafts running front to rear.  I had the same concern about drive train stress, but went with portal hubs and 8T/24T gearing at the wheels so the bevel gears and axles are at low torque.  The downside was I couldn't figure out how to get the motors between the wheels with this arrangement.

Here's a render I did for the instructions.

I can take some photos of the finished model tomorrow.

[JLiu15]

On 12/31/2020 at 1:20 AM, pdw said:

Yes, two driveshafts running front to rear.  I had the same concern about drive train stress, but went with portal hubs and 8T/24T gearing at the wheels so the bevel gears and axles are at low torque.  The downside was I couldn't figure out how to get the motors between the wheels with this arrangement.

Here's a render I did for the instructions.

I can take some photos of the finished model tomorrow.

Just wondering - what software did you use to create this? I use Bricklink Studio, and honestly it's missing A LOT of pieces...like the XL linear actuators 

Edited January 4, 2021 by Milan
No need to quote the pic from the previous post. Thanks.

[pdw]

1 hour ago, JLiu15 said:

Just wondering - what software did you use to create this? I use Bricklink Studio, and honestly it's missing A LOT of pieces...like the XL linear actuators 

Yes, it's Studio, and yes, the XL actuators were a problem.  I managed to add them as custom parts by downloading them from ldraw.org, and importing them into Part Designer, but it wasn't entirely straightforward and I don't recall exactly what I did to get it working.

The only other part I struggled with was the universal joints as Studio won't let you bend them, so I had to assemble them from their components, which of course messes up the parts lists export.

Here's the finished model: 

It's based on a Caterpillar 216B.  

[JLiu15]

UPDATE 1/4/21

Made a little more progress on the model. I've got the Mindstorms Robot Inventor hub installed now; I put it on its side and low in the chassis to lower the center of gravity. Because there's no screen I need to look at like on the EV3, there's only two buttons that I need to press on the hub - the power button and the bluetooth button for pairing. I can simply listen for the power on/connected/power off sounds to know the hub status. Thanks to this, I don't anticipate needing to create any opening parts on the body to access the hub - maybe just some pieces integrated into the body that can hit the necessary buttons.

I've managed to route the mechanisms on this model through a small space. Both the arm elevation and bucket tilt will be controlled by C+ L motors sitting side by side, which makes for a nice symmetrical layout. The left motor controls arm elevation and is connected to port E, while the right motor controls bucket tilt and is connected to port F. Ports A, B, C, and D power the medium angular motors that propel the model. Arm elevation will be done using XL linear actuators, which I ordered off Bricklink but have yet to arrive. As for the bucket, I'm planning on using the large bucket from the Volvo sets. It won't be the most realistic bucket for a skid-steer loader, but I definitely prefer that over using a custom bucket. I might also make interchangeable attachments for the model, such as a pallet fork.

If you have any suggestions for me, please let me know.

Photos:

Edited January 28, 2022 by JLiu15

[JLiu15]

UPDATE 1/9/21

Lots of progress here. The majority of the bodywork is done, especially around the cab. The rear still looks like a crude black box, but there will be yellow panels going around that area once the arms are in. The cabin is complete with a driver's seat, and a good amount of tiles were used to give it a clean finish, almost like a Creator model.

Initially working on the bodywork proved quite discouraging, as I felt like I was just building a box on wheels. To make things worse, the teal Mindstorms hub was an eyesore. I did the best I could do conceal it, only leaving a small opening for the speaker as one of the features I programmed into the control profile is a backing alarm when driving in reverse. Fortunately this area should be pretty well concealed once the yellow body panels are installed. Note that the attachment points for the arms and LAs are also in place.

Photo:

Edited January 28, 2022 by JLiu15

[chlego]

Nice!

[1gor]

It is starting to take correct shape 

[JLiu15]

UPDATE 1/10/21

I've got the arms built and installed for the model. They are elevated with 2 XL linear actuators. The bucket is tilted using 2 large LAs, and is meant to be detachable as I might also make a pallet fork for the model that can be interchanged with the bucket.

All I got left to do is add the rear body panels, and the model is complete. If all goes well, I should be able to finish it early next week.

Photo:

Edited January 28, 2022 by JLiu15

[Maaboo the Witch]

Cool work! It does look like a Case model.

[trekman]

That is a mean looking loader.  it will be interesting to see a video of it working when you get to that stage.  it looks like a nice solid build.

[johncarpenter]

This is looking really nice. Do you have a picture of the chassis from the top and the back? I would be interested to see how you packaged the motors and gears for the arms and the bucket. Is the chassis 11 studs wide?

I built a skid steer a while back, in a smaller scale, and had a lot of headaches packaging everything in. My chassis was 9 studs wide, so only 7 studs wide inside.

[Thirdwigg]

Just seeing this now. Great project, and it's starting to take a nice shape. 

[Milan]

With the back section, it will look even better. Looking forward to it. And to see how it performs.