should remain disengaged to allow the differential to function
normally and should engage only when a slip situation
stops the vehicle. Real off-road vehicles come with manual or
automatic locks that engage when a slip situation is detected
and disengage when the vehicle drives out of it. LEGO differentials
can be locked manually with relative ease; doing
this automatically is also possible, but it’s extremely complex
and impractical. Figures 8-4 and 8-5 show simple manual
differential locks for all three variants of ready-made LEGO
differentials.
LEGO differential locks use transmission driving rings
(#6539) that can be engaged and disengaged using a
transmission changeover catch (#6641). The catch can be
controlled remotely with a motor or with pneumatics. The
latter solution is more convenient if there are many locks on
your vehicle that move together with the suspension. Note
that it’s not necessary to put a lock on every differential on Figure 8-4: LEGO’s oldest (left) and newest (right) differentials can
have locks made of four extra gears and a transmission driving ring,
which locks the two outputs together, disabling the differential. With the
latest variant, the lock is 1 stud narrower than on the first.