Description

PORTAL AXLES FOR THE G-CLASS

LeTech and the term “portal axle” are often used in one breath. But the portal axle isn’t our invention. On the contrary, the principle of the portal axle has been used in vehicle construction for quite some time; the design has been used in a similar way in “Unimog”, “Zetros” and “Lapplander” vehicles.

We receive questions about the meaning of the term “portal axle” almost every day. Wikipedia has a compact explanation: “A portal axle is an off-road vehicle suspension and drive technology where the axle tube or the half-shaft is off-set from the center of the wheel hub and where driving power is transferred to each wheel via a simple gearbox, built onto each hub. This gives two advantages: ground clearance is increased, particularly beneath the low-slung differential housing of the main axles – secondly, any hub reduction gearing allows the axle half-shafts to drive the same power but at reduced torque. This reduces load on the axle crown wheel and differential. The portal gear configuration is also sometimes called a drop gear or drop gear set configuration. Compared to a normal layout, portal axles enable the vehicle to gain a higher ground clearance, as both the axle tube and differential casing are tucked up higher under the vehicle.

The question remains: Why all this effort?

Keyword “ground clearance”
The portal axle creates real ground clearance. The construction creates the only possibility of increasing the distance between the axle bridge/differential and the road in a meaningful way. Suspension lifts through suspension springsor body lifts might raise the body but only increase real ground clearance in a very limited way, namely at most by the tyre size.

The LeTech portal axle works with an offset of 150mm, the used tyre size of 37×12.5 R18 (alternatively 325/55 R22) lifts the G-Class by approximately another 100mm. Or to put it another way: the LeTech portal axles generate an additional ground clearance of around 250mm. With impressive practicability: The portal axle G drives over an obstacle between the wheels with a height of almost 450mm without touching it!

Keyword “big wheels”
Wheels with a bigger diameter increase the ground clearance of the vehicle and therefore increase off-road capability. The clearly increased width of the used tyre supports the abilities of the G to go off-road: The enlarged contact area reduces the ground pressure per area which again makes it easier to gain tractionunder difficult conditions. These facts can be supplemented by lowering the air pressure in the tyres and therefore enlarging the contact area – the contact patchof the tyre – enormously.

Keyword “comfort”
An often underestimated but extremely significant side effect of big wheels is the unparalleled increased drive comfort, especially off the beaten track. The bigger the diameter of the tyre, the less it gets flustered by road bumps, the easier it rolls over obstacles, the less are the shocks and vibrations transmitted. The vehicle itself is under a lot less stress; technology, body and load are protected and –very importantly – driver and passengers have a comfortable driving experience.

The effect can be increased by playing with the tyre pressure, as bigger tyres have a much higher air volume. The easiest way of adapting the desired comfort to the road conditions is with the variable air pressure of the large air volume – the principle of air suspension.

Keyword “transmission”
A decisive disadvantage of big tires can be the impact on the overall transmission of the vehicle. That’s why the designers of the vehicle thought up a perfect concept which transports the speed and torque of the engine to the wheels. Engineers have synchronised the transmissions of gearbox and automatic transmission, transfer case, axle transmissions and wheel size and, in the best-case scenario, even reconciled common exhaust regulations. Now, the dedicated off-roader with the big tyres comes along and jumbles up the complete system. The wonderful rolling circumference doesn’t harmonise with the rest of the overall transmission, often the 5th or 6th gear just collects dust in the gearbox as it isn’t being used, as the engine torque cannot fight the driving resistance anymore. These challenges are elegantly bypassed with the portal axle, as each axle portal contains a gearbox with perfect transmission for restoring the original conditions of the overall transmission. In a nutshell: The portal axle makes a transmission possible which neutralises the influence of the tyre rolling circumference for the overall system. The components from engine to axle shafts don’t even notice the big tyres, as they continue to work in the usual speed and torque ranges for which they were designed.

Keyword “central tyre inflation system”
Only the portal axle allows the air feed through the hub thanks to the offset between drive axle and wheel axle. The compressed air provided by the compressor is transported to the portal housing via suitable tubesand custom-made pipes and conveyed through the wheel hub to the wheel via a suitable connection. The wheel itself has an internal connection from the hub area to the rim well and therefore to the tyre. This gives the portal axle G driver the privilege of adjusting and influencing the air pressure of his tyres while driving – from the driver’s seat.

Keyword “look”
A Mercedes-Benz G-Class with LeTech portal axles is absolutely top class. More “G” simply isn’t possible.

LeTech Portal Axles for the G-Class
We at LeTech have adapted the principle of the portal axle for the Mercedes G-Class also known as a G-wagon and developed it into series production. The development and construction of the portal axle is a crucial and decisive factor in the history of the company and the LeTech brand. If you’ve read the text up to this point, you will probably have two crucial questions:

Firstly – why doesn’t my G have LeTech portal axles yet?

And secondly – how can I finally get LeTech portal axles for my G?

Question number one can actually only be down to a lack of information, which should have been dealt with here. For question number two there are different approaches.

The vehicle market already has various special models of the Mercedes-Benz G-Class on offer which are equipped ex works with LeTech portal axles:

G 63 AMG 6×6
G 500 4×4²
Maybach G 65 Landaulet
G 300 CDI LAPV (…available for customers with their own army military sales only)

Although LeTech has delivered almost 5,000 portal axles for the production of the G-Class to Graz, the market is very manageable. This is precisely why every suitable G-Class can be retrofitted with LeTech portal axles.

Besides the conversion of two axles per vehicle, LeTech also offers six driven wheels including portal axles. There are (almost) no limits to your imagination. Please contact us for more detailed information and an individual offer.

Note: Images may show equipment details which are not included in the scope of delivery.

Notes: This part may be considered a Special Order if custom-made, low volume, or not something we generally stock. There may be a cost for Air Freight, Customs, Taxes, and Duties. Your card will not be charged during Checkout; only an Authorization will be obtained. If necessary, we will contact you with details before processing the order.  Please review our Terms & Conditions before ordering.