So, time again to start a new project. After getting some inspiration from Lasse's work, I wanted to also create something small and usable. My idea was to create a small forklift that could be fully remote-controlled and that would fit in the Model Team Lasse uses. However, after I tried to squeeze the necessary gearing into that small area, I noticed that it was really tought and while the whole thing could be done, it would look awful. Thus, I wanted to upgrade scale a bit and widen the structure by two studs. After some tinkering, I was able to design following:

What you are seeing is the internal gearing of the forklift. Basically, there is four functions (let's call them F1-F4) that are controlled by two motors (M1-M2). General concept of the creation is that the M1 can control which function M2 is powering while also powering it's own functions. To let you readers understand bit more what's going on, let me elaborate:

• M1 (dark purple) is responsible for handling two functions, steering (F1 - the rear axle - green gears) and tilt (F2 - small linear actuator - light purple).
  
• When F1, i.e. steering, reaches maximum angle, the differential right infront of M1 starts to move. It runs the F2 and also, via small clutch, the gear changer that is infront of M2.
  
• F2 can therefore run indepently from the gear changer.
  
• M2 (light purple) runs either front axle drive (F3 - front axle - blue parts) or lift (F4 - drum roll - lime parts). Since F4 is sitting on axle with stud on the end and the stud is sandwiched between holes, F4 can stay in one place under small load.
  

This picture from under the gearing may also help you out. After finishing with this LDD design, I made brick-version of it to get some real usage experience:

I am fairly happy with the design althought few things came up after using it over one weekend at LEGO event:

• Current rear axle is not really working as sometimes it drives over the "guards" that I have built in. When that happens, the whole thing stops working as the engine cannot produce enough power to free the axle. I think the best way to get rid of this is to change the rear axle to standard two-wheel axle. That would make it simpler to build stronger guards.
  
• Since I used M-engines, remote-controlling the vehicle takes effort to learn since everything works on super-speed. You need to be very careful not to "overdrive" any functions. For example steering and driving is hard since the vehicle responds like annoyed little chihuahua, only using max speed and maximum turning angles. I think switching over to XL engines would be useful since that would slow everything nicely. Of course, adding extra gearing is also possibility but somehow I feel that XL engines would be better bet.
  

More pictures at Flickr and Brickshelf.

I love these little projects full of parts and functions, I will follow with attention.

Nice work, @TheQ. I also like these small models that are packed full of features.

To prevent the winch from unwinding, you might want to consider using a worm gear in there somewhere. Worm gears have the advantage that they can't be back-driven, and they can reduce the speed of the drive-train quite a lot in a small space. Eg. when coupled with an 8 tooth gear, the output speed will the 1/8th of the input speed. Sariel's Gear Tutorial talks about the properties of worm gears (about half way down the tutorial).

A worm gear could also be used to slow down the steering too.

If the scale is getting larger than you wanted, you could turn it into a larger forklift that lifts shipping containers, although they tend to have 2 wheels at the back.

I look forward to seeing your finished model.

Edited May 30, 20177 yr by Splat
Fixed typo.

That is looking pretty good, and omg what small. How can u mount the BB?Nice steering system . GL with building.

From what I can tell, M1 drives the switchring on M2 right? If so, I can't see the purpose of either the steering wheel or actuator, as the vehicle would stop moving if turning left (for instance) and move if turning right. Also, the actuator wouldn't move at all because of the switchring function.

Am I completely mistaken here?

Edited December 13, 201212 yr by Carsten Svendsen

This looks great,I look forward to more updates.

Edited December 13, 201212 yr by Alasdair Ryan

From what I can tell, M1 drives the switchring on M2 right? If so, I can't see the purpose of either the steering wheel or actuator, as the vehicle would stop moving if turning left (for instance) and move if turning right. Also, the actuator wouldn't move at all because of the switchring function.

Am I completely mistaken here?

Yup, you are

The axle can't go through the switching part, because there's an axle-pin there.

From what I can tell, M1 drives the switchring on M2 right? If so, I can't see the purpose of either the steering wheel or actuator, as the vehicle would stop moving if turning left (for instance) and move if turning right. Also, the actuator wouldn't move at all because of the switchring function.

Am I completely mistaken here?

The actuator does move. There is simple clutch between it and the stick of the switch ring that allows actuator to move while making sure the stick can just move around 90 degrees. The clutch is made out of two 6587 Technic, Axle 3 with Studs and Technic, Axle and Pin Connector Angled #1. As far as the functionality of the steered wheel goes, it works like this: After the wheel is maximum position (say, 65 degreed to left), it stops. Since it hits "dead end", it cannot move to that direction any more. However, differential is then engaged and it starts turning. The differential moves the gears that are connected to actuator moving it and also, via the clutch, they move the stick that controls the switch ring. However, stick can only move around 30 degrees to certain direction until it is stopped. However, the actuator can finish it's movement because the clucth does not have any effect on it at all.

I definetly need to get a video that will explain how it works

Recently I was working on a three wheel forktruck, where the angle of the rear wheel determined the rotation speed of the two front wheels. This allowed the front wheels to drive and differing speeds and directions. The only way to get this working properly (in my opinion) was to use the NXT. Two nxt motors drove the front wheels, and then a buggy motor drove the rear wheel. A colour sensor picked up different colour zones which were located just above the rear wheel, and sent different speeds and directions to all three wheels. This then mimicked the actual working of a three wheel drive Mounty style forktruck that you would see on the rear of a lorry.

Whilst the concept worked very well, I then ran into problems packing the NXT brick and bulky motors into a tiny foot print. I ended up forgetting about the NXT version and opting for a system where the two front wheels are driven from motors through a switching gearbox. The rear wheel is now a trailing castor. (ala shopping trolley) The downside is that the rear wheel trails out further than the rear of the vehicle. But at least now the model works and was built within reasonable proportions.

The moral of the story is that sometimes things are difficult to exactly implement as in the real thing. What you have done is very good, and I too would be blown away if you could get it working really well.

If you are experiencing problems with the 'gearbox' why don't you try a 3 function gearbox Allanp made me this one....

Edited December 15, 201212 yr by Alasdair Ryan

Nice work so far. Looking forward to seeing the finished MOC.

Here's small video I took to explain the functionalities of the creation bit more. I was bit lost at words so I did not add too much explaining text to the video. Hopefully you can still get the idea how it works! And no, I did not take video of it moving around as I am not satisfied with the movement. Please also remember that this is still in WIP stages and thus there are many "errors" in the creation. Still, this video should explain the concept of the creation.

PS: Sorry for slight light flickering, my "studio lights" are getting a bit old.

The axle can't go through the switching part' date=' because there's an axle-pin there[/quote']

Ah, just noticed that there was error in that picture. The axle pin should be changed to axle with a pin in the end. The video shows the correct part.

Wow, this looks amazing, looking forward to further progress! I imagine controlling it will be quite challenging!

Looks like it'll work great. I still don't understand how it controls the gearbox. Do you have a pin+joiner or something to work like a clutch gear?

Edited

Edited December 17, 201212 yr by Alasdair Ryan

Carsten, I used following bricks to make the clutch:

+ + - Pins are put inside the round hole. One axle is connected to the small linear actuator and another one is connected to the gearbox's stick.

It works quite nicely, althought sometimes it requires some tinkering to loosen the connection a bit.

Edited December 17, 201212 yr by TheQ

aaah that makes much more sense. However, doesn't it require a lot of force to prevent them from falling out of the ?

aaah that makes much more sense. However, doesn't it require a lot of force to prevent them from falling out of the ?

As far as I have tried, the connection is quite stable and strong. Naturally, I have added frames around that so that the stud-axles are always compressed. Actually, sometimes I have opposite problems: The connection is too strong and the stud-axles have a bit of hard time moving around!

Belated post here due to severe registration problems. This thread inspired me to take on the challenge of a 3-wheel forklift again, but at a smaller scale than my previous semi-failed attempt. Mine has no gearbox so all four functions (drive, steer, tilt, lift) have their own motors (the tilt is not so prettily placed on the top of the cabin so far), thus the body is slightly larger and bulkier, especially with the battery box on board. Anyway, the reason I thought I'd make this post is the rear wheel drive and full steering that I set as my chief prority for this model. It's not perfectly rigid of course, but with the drive M-motor sufficiently geared down (it has to be for a reasonable degree of control anyway) I have no problems with gear slippage. This picture is half a month old, but this part of the model is still the same, I just have more on top.