Lockers ! by Nadim Samara
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Lebanon land Rover Union publications |
Lockers !
by Nadim Samara
The first thing people think a 4x4 does is make
ALL 4 wheels on the ground drive the car in the desired direction. That is very
far from the truth. With so many of today's nifty 4x4 systems, no wonder people
are not understanding the concept.
Without going into any details of the given
Land Rover full time 4x4 system, I just want to say that the standard Land Rover
relies mostly on one front wheel and one rear wheel at the same time when it
exits the showroom. This is due to the center differential lock, which enables
the power of the engine to be split 50% to the front axle, and the other 50%
to the rear axle. However, with no axle differential locks, the Land Rovers
may sometimes find yhemselves helpless when crossaxled, when both a front and
a rear wheel are up in the air, or have no traction. You see, once the 50% power
goes to the front axle for example, it is then divided up along that axle (50%
right & 0% left, 40% right & 10% left...or ideally 25% & 25%). However, the
power supplied will take the path of least resistance. Since it is easier to
turn the wheel that is in the air, or that has no friction, then ALL the 50%
will go to that wheel, rendering the other front wheel that may have traction
helpless. The same may occur with the rear axle. Therefore, once one front wheel
and one rear wheel are spinning uselessly in the air, the Land Rover will stop.
Enter the axle differential locks. With a total of three differentials (a device
used to differentiate speed at the two given ends), Land Rovers come with one
that is locked: the central one. That leaves both the front and the rear "open".
This term means that the two wheels at both ends of the axle do not turn at
the same speed. This is beneficial for street use, or where traction is abundant.
However, in offroad situations, that is rarely, even never, the case. The differential
locker is a device that enable both wheels on the axle to turn together, thereby
considerably enhancing traction. The lockers come in many different shapes and
sizes. They may be automatic, hydraulic, air operated, cable operated, or so
forth. Alongside lockers that provide 100% traction are Limited Slip Differentials
(LSDs). These however are not full lockers, and will therefore be addressed
in another article. Of the many lockers available on the market for Land Rovers,
two are very popular: the Detroit Locker (DL), and the ARB locker (ARB). These
are fully lockable differentials, and are of similar strength when installed
in Land Rovers. However, that is where the similarities end. The DL is an automatic
locker, that functions through a locking mechanism that "knows" when to lock,
and when to unlock. The DL may only be installed in the rear of a Land Rover
as it deteriorates the front-end steering assembly. I have to be honest and
say that I have never driven a Land Rover with a DL in the rear, but I hear
mixed reviews of the product. Some say that is has a ratchety sound when locking
and unlocking, that it is jerky and not smooth, and may hinder the control on
ice, snow and side-slopes. However, for simplicity, toughness, and effectiveness
on the trail, it rules. The ARB is a manual locker, that is to say that there
is a button on the dashboard that enables the driver to engage the locker, or
disengage it to have a normal "open" diff. This gives you the best of both worlds.
The system is actuate by an air pump that moves a pin inside the differential
and locks the two sides of the axle, ultimately creating a spool (a single axle
from wheel to wheel). If this seems complicated at first, well, it is, but ARB
has made it quite user friendly. It is more difficult to install than the DL,
and requires an air pump and electrical work, but the end result is most beneficial
for Land Rovers. Moreover, it can be fitted to either the front or the rear
of Land Rovers, since its selectability will not hinder steering up front. Moreover,
on icy grounds where lockers are not favored, the ARB may act as a conventional
open diff. In conclusion, the DL is like the ace of spades...always the toughest,
always on top...however, the ARB is like a joker, it can be whatever you want
it to be...even the ace of spades! These are the websites for both products:
ARB: http://www.arb.com.au/
DL: http://www.tractech.com/
The decision on which one to get is usually difficult. I have been debating
for two years which locker to get for the rear of my Disco. I have finally decided
on the ARB for its driver control, dual purpose, and for the fact that the air
pump can be used for several other things. Mind you though, a DL can run for
only 450$ in the US versus the 650$ of the ARB alone, with the pump add another
200$. Therefore, the DL is a bargain indeed. If you have any questions, please
refer to the manufacturers' sites, or visit any of the retailers on our links
page. Ultimately, you can email us to help.
Happy Rovering,
Nadim Samara