jebster's tonka truck rc conversion

[jebster]

When I was visiting family this summer I came across my old tonka trucks and it gave me a flashback to when I was a kid. I always wished I could control them so many years later I am going to make it happen.

I picked a front loader and dump truck from the lot to do the conversion because they were in ok condition.

I started work with the front loader. Given the pivot for steering I decided MOA was the way to go. The space for a standard MOA axle up front was very tight and the back was pretty shallow to hide an axle without major surgery (which I wanted to avoid). Looking through all my parts binds I released I had a set of MOA converted lcc axles. Perfect.

To give the loader a little suspension I made the rear axle a simple pivot. I used o-rings to provide a little tension.

To do the steering pivot I came up with a shaft that locks into the front half with a lever arm that an actuator hard mounted to the rear half will push & pull against.

The battery will tuck right inside the engine compartment in the rear of the loader. I'll run the battery line underneath and back up to the cab area, which is where the esc, rx and bec for the actuators will sit.

The loader arm and bucket have been installed with nylon bushing to prevent metal-to-metal wear.

I slapped some 2.2 tires on just to take a look. They are too big but I'm struggling to find tires I like in the right size. I need something about 4.5" tall that have a construction tire look. Rc4wd mil spec tires are close.

Still need to get all the actuators and get them installed. One for steering, one for the bucket tilt and two for the main lift. After that it will be all about sandblasting, priming and painting. Going to go with CAT yellow.

[jebster]

Also have the dump truck I'm working on. Not as far along, just sizing thing up to determine layout. This one will be getting bully axles on leaf springs. Chassis needs to get cut to allow the axles to pass through and have some suspension travel.

The dump will be handled by one or two actuators.

More to come.

[jebster]

Got the dump truck chassis trimmed up for axle clearance. Mounted up the leaf springs. Front fits fine but the back extends beyond the chassis so I'll have to add some type of brackets. I was able to keep the servo tucked in on the axle, which was a plus.

[JatoTheRipper]

This is really cool!

[IVIaarten]

I love stuff like this. Great work.

[calcagno45]

I've been wanting to convert a dump truck for quite a while. Nice job so far.

[jebster]

Originally Posted by calcagno45

I've been wanting to convert a dump truck for quite a while. Nice job so far.

Originally Posted by IVIaarten

I love stuff like this. Great work.

Originally Posted by JatoTheRipper

This is really cool!

Thanks everyone. I am having fun with this.

The one challenge I would probably have is on the front of the dump truck. Clearance with the wide chassis and the stock wheel wells could limit steering. Time will tell.

[jebster]

Added some box steel to the rear to provide mounting points for the leaf springs. Realized the rear of the chassis is pretty flexible so I'm going to have to do some work. I may be able to braze the side rails to the rear plate.

I also found some tires with the right diameter that look ok. They are wider than I wanted so I bought one set to try out. Worst case they can go on the front loader. http://www.ebay.com/itm/2pc-2-2-Off-...72.m2749.l2649

[Mike Flea]

The tractor looks like it'll be a blast, looking forward to a video of it

[ren.dnb]

Looks great so far! If you have snow where you are during the winter, maybe it can clear your sidewalk for you lol.

[jebster]

Had some time to start setting up the lift on the dump truck. Geometry is about where I want it but I am concerned about the lifting power. I took a video of the dump operating empty and another one were I threw in a 5lb weight. The actuator does strain more than I wanted. I will have this set up such that I could easily add a second actuator, although they are expensive.

https://youtu.be/czEI-g_VBLo

https://youtu.be/leUj_eQnIag

[jebster]

Originally Posted by ren.dnb

Looks great so far! If you have snow where you are during the winter, maybe it can clear your sidewalk for you lol.

Definitely get snow here. And I hadn't thought about it but that could be fun. Pair these up with my 6x6 with its plow or snowblower attachment. Could be a complete snow removal crew!

Originally Posted by Mike Flea

The tractor looks like it'll be a blast, looking forward to a video of it

I'm itching to wire it up myself and give it a try. The actuator for steering should be in this week. Once I have that I will be able to take it for a spin and take a video. The rest of the actuators for the lift and bucket will be coming in later.

[jebster]

Spent a little time on the front loader lately. After getting the shorter actuator I was able to set up the steering. Everything is lining up and working. Like with the dump bed the actuator seems a little under powered but then I realized something. I'm running them through the rx at 4.8v right now and they are rated for 6v. I would expect a little better performance once they are hooked up through the bec I had heyok make me.

I also had my tires from China arrive. The good news is the compound is pretty firm, which I wanted. The bad news is they are a little shorter than advertised. Mounted up on a narrow beadlocks I think they will be ok.

Short video of the steering and some pics of the tires.

https://youtu.be/3BVY4PEbxBg

[Mike Flea]

That's going to be cool!

[jebster]

Got the loader wired up and running today. Mixed bag of results.

The good:
- LCC axles working well. Plenty of power and some speed. When I turn it does have a lot of push so I will be changing the rear pinion to get some underdrive
- The steering actuator setup does work
- I like the size of these tires

The not so good:
- The tires are very stiff. Granted my basement concrete floor doesn't have much traction
- The actuator for steering may not work. It has a hard time getting the pivot to move. Plus the slow movement of the actuator makes it difficult to steer.
- I was planning on using a stick radio but I have discovered I have no coordination. Back to a pistol for me!


For the steering I'm wonder it a high torque servo might be better. Have to think this over.

https://youtu.be/YoED0Z9nDnU

[jebster]

Been thinking through the steering situation. I'm leaning towards a high torque servo mounted in the cab using a gear drive setup to do the turning. I'm saw the following parts which might do the job:

https://www.servocity.com/32p-25t-3f...vo-mount-gears
https://www.servocity.com/0-250-1-4-...t-pinion-gears
https://www.servocity.com/0-770-set-screw-d-hubs
https://www.servocity.com/shafting-t...eel-d-shafting

May have to order some parts up.

[Mike Flea]

When I watched the short one up above of the steering, there were other hobbyists that had Tonka Loaders also, did you happen to check theirs out? Couple guys were using the metal gear servos, one of them had real good articulation

[jebster]

Originally Posted by Mike Flea

When I watched the short one up above of the steering, there were other hobbyists that had Tonka Loaders also, did you happen to check theirs out? Couple guys were using the metal gear servos, one of them had real good articulation

I did see a video or two. Doing the numbers a good high torque servo has quite a bit more power than the actuator plus it is fast. One video showed a guy using connecting rods for the pivot. I'm don't have the space for that with my setup, which is why I'm considering the gear path. Given this whole project is an experiment just having fun trying things out.

[jebster]

More work on the dump truck today. Mounted up the axles and threw on the tires to size it up. I like it a lot! The only thinkg is the wheel wells are too close so I'm getting a lot of rubbing. I'll have to put in some blocks between the leaf springs and the axles to get about 1/4 - 1/2" additional clearance.

I cut an opening in the cab top that will be hinged to allow for battery access. I also made an electronics deck and battery tray for the interior. Used my favorite material for interior structures: kitchen cutting board!

[jebster]

Moving along on the dump truck. Got my battery latch mounted. Using a magnet to hold it in place. Also made my lift blocks to give the wheels some clearance so now they don't get hung on the wheel wells, or at least not enough to care about.

I also doubled up the actuator mounting setup. I still only have one actuator but when I get a second it is ready to go.

Here is a short video of it in action and a few pics. I really wanted to wire up the motors and try a test drive but I don't have any wire for the motor leads!

https://youtu.be/XyqHvwpYm0Y