Mini linear actuators are technic parts that mimic hydraulic cylinders and convert rotary motion into linear motion. They are primarily used in combination with power functions to perform minor mechanical tasks, but their scale suggests that they could be used to mechanize smaller town models as well, though I haven't found anything after a cursory search on this forum.

I made these two models to show a couple of examples of how they may be used. The excavator arm and dump truck tipping mechanism both use mini linear actuators to add mechanical complexity to otherwise small and compact models.

Here they are from another angle.

Here the mechanics of the excavator are exposed. The boom is operated through a worm gear mechnism by the knob on the left of the "counterweight", and the arm is extended with the one on the right. Both mechanisms are geared so that two full revolutions of the knobs is sufficient for the full range of motion.

I hope others might find these parts and techniques useful in their own builds!

Edited January 12, 201411 yr by majorna

Excellent! I like how you've used these Technic components to Town sized MOCs. They look really good.

Very nice mocs,you did well to fit the technic parts into small city mocs.

Nice work and functionality.

Excellent engineering there 'majorna', awesome to see working machinery in minifig scale......Brick On 'majorna' !

These are really nice; it would be neat to see this done in an official set.

I don't know if I like the digger (the functional arm is nice but looks much less refined than non-functional varieties). The dump truck, on the other hand, is beautiful! But does it fit a minifigure in it? It almost looks like the linear actuator takes up needed cab space.

I like the functionality of the technic design but without losing the lego feel and familiarity :)

Thanks for the comments everyone. I made these models more as an exercise in showing what could be done with these Technic parts than anything, but am relatively happy with the results. I have an idea of how to slim down the excavator a bit to allow better sculpting of the body and counterweight. The truck was made more as an afterthought, though I am much more pleased with it aesthetically. Unfortunately it is just a bit too small for a minifig. It is only 4 wide, so that's not so strange. The linear actuator would easily fit in a "Great Vehicles" scale model, and this would even allow the action to be geared up a bit. As it is the mini actuator requires 19 revolutions for full extension, but squeezing in a 24:8 gear pair somewhere in the model (as I managed in the excavator) would help this significantly.

It's not really my area of expertise, but the truck looks really slick and the action is terrific.