So let’s find the weak link in our chain. In our example from
Figure 11-2, we have a motor connected to the axle, an axle
connected to the 8-tooth gear, an 8-tooth gear connected
to the 24-tooth gear, and so on, all the way to the output
and the wheel.
Most of the axle pairs (or other connections) in this chain
are within a single LEGO brick. But the connection marked by
red arrows in Figure 11-3 involves two 2×4 Technic bricks,
meaning that when stress is applied, it can break apart (as
shown in Figure 11-4). When deciding where to reinforce
your model, look for the seams that could separate under
stress.
Also note that a pair of gears that increases the gear
ratio (the driver gear is bigger than the follower) is more
likely to come apart than a pair that decreases the gear ratio
(the driver gear is smaller than the follower). There is simply
more force exerted on the follower gear when gearing up,
and such a pair of gears is a good candidate for reinforcing.
Figure 11-5 shows one obvious way to reinforce our
mechanism: We simply replace the two pairs of 1×4 bricks
with two 1×8 bricks. On the upside, the weak seam is now
gone, every link in our chain is solid, and we no longer need
to use plates. Additionally, this solution adds no weight
and takes up no extra space. The downside is that using
long, solid bricks can be an invasive way of reinforcing,
and building in this way is time-consuming and extremely
inconvenient with complex gearing, as you’ll have to place all
elements at the same time.
Figures 11-6 and 11-7 show another way we can
reinforce our mechanism: by adding support beams. This
increases the weight of the mechanism and takes more
space, but it involves only minimal changes to the original
structure. Note that structures like the one shown in Figure
11-7 have the downside of added friction because the
yellow bricks are partially supported by the axles—building
compact mechanisms can come with a cost.