Today, TBs will examine and present the details about the new LEGO Technic mini Linear Actuator (mLA), which will debut into the new 8069 Backhoe, already in the 1H2011.
With this post we aim to show you, how it works and its internals.
1. One first look
The new mLA (element ID: 92693) is delivered as one single element, thus not needing or having different interchangeable coupling brackets available, unlike its larger predecessor. Despite the small size, it looks quite robust, well designed and produced with the highest quality standards.
From the images below you can see how the mLA compares with its big brother, the classic Linear Actuator (LA), and also a couple of possible gear combinations (5:3 and 1:1 ratios) allowed by the mLA bracket geometry. Notice this geometry is exactly the same as in the 61904 bracket for the larger LA, thus making their connectivity requirements quite identical.
Because the classic LA cylinder is larger and thicker, it fits nicely on a 3L wide bracket. However we can't say the same from the new mLA, which cylinder with 1L diameter is much thiner than its 3L wide bracket, making it look a bit "clumsy". But this is probably the only possible design, that allows for the use of existing Technic bevel gears.
Somehow it seems the mLAs will always exhibit a disproportional fit, in the models where they will be used. Time will tell if I'm making an incorrect judgment.
The mLA is 3L wide and 7L long when fully retracted. It has a 3L course, thus extending to a maximum length of 10L.
In order to full extend or retract, the mLA axle needs to complete 19 revolutions.
2. The inside view
In the video below you can see one of the simplest mLA setups being exercised, its inner parts as well as how to put them apart.
Please notice the disassemble steps look that easy, just because the mLA was already disassembled once before, otherwise it should have taken a lot more effort to break it apart. Also the "collar" that may be seen near the sleeve extreme in the photos and video below, is not an original characteristic from this part, but instead caused by the stress it was subject at the first time disassemble...
Unlike some of you may have expected initially, there are no metallic elements used in this element, as all the mLA subparts are made of plastics.
This should allow the cheapest production costs, thus making it possible that one single set from the mid cost range (8069, Backhoe), can include a good bunch of them.
All the subparts can be seen with more detail, from the few following images.
As seen from the above, like its bigger brother the mLA also features an internal clutch mechanism for both ends, thus making it usable with motorized functions. However this mLA part, is not suitable for other functions than those dealing with relative small loads.
But this is an issue to analyze with more detail ahead in this post.
The clutch function is achieved through the smart design of the tip from the inner rod, which runs into the sleeve inner screw, as seen also from the images above. The tip has two threaded turns on the surface, and a flexible design that allows for its contraction whenever one of the mLA course limits is reached, thereby making a thread pitch jump every turn, while it continues to run.
Lets say the clutch mechanism should be the most clever element developed for this mLA. I would not get surprised at all, if this genius clutch solution itself, was registered in the Patent Office by TLG.
Now, it's time to see it in action...
I took the opportunity to develop a bit my 3D modeling skills and here are the results. Hope you to like them.
3. The load tests
But... as stated before and as the video above also suggests, these mLAs were not designed to deal with the heaviest loads on earth. Not at all...
Using a very similar setup to the one once used to measure the classic LAs strength , we have now made some new measurements to compare all the LEGO LAs (including the newly redesigned classic LA, after its bad fate under the heaviest demands from the new 8043, Motorized Excavator). The load performance tests were made with both PF M and XL motors, for each LA tested.
mLA load performance with M and XL motors.
Linear Actuator load performance (version 1, production code ≤35X0) with M and XL motors.
Linear Actuator load performance (version 2, production code ≥36X0) with M and XL motors.
As you may see from these results, and as already expected, the load capacity from each LA does not change significantly whether it is driven with one M-motor or one XL-motor. Although the values observed tend to decrease on successive tests, but recover after some rest.
The tests also confirmed the mLA has a much lower performance than the larger and more robust classic LA. The mLA sustains up to about 900g, before yielding to the load, while the LA sustains up to 4.100g - 5.200g depending if it is used the first LA release or the recently updated release.
From the results observed the first release LA now tested, seems to be a bit stronger than those tested in the post above mentioned. Probably it may be explained by small variations among the characteristics from different LAs, their use condition (to which these first LAs were quite sensitive ) or even by the small modifications made to the new test setup.
Is the mLA what you were expecting?
The 8069 (Backhoe) should soon hit the market shelves, so that you could try the mLAs yourself.