Technical domain
  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:
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