Portal axles are a feature sometimes found on full-scale off-road cars and trucks. The basic concept is that gears located near the wheel hubs allow the axle to be offset above the middle of the wheel. This provides increased ground clearance, which is often a handy feature when off-roading.
Until recently, I had never seen an RC vehicle with portal axles. That changed when I found an advertisement for the Traxxas TRX-4. It includes these types of axles as standard equipment. I was interested to see if portal axles are actually useful in 1/10-scale. Traxxas provided a TRX-4 Tactical Unit ($450) for this review.
The TRX-4 is a factory-built model that includes a 4-channel 2.4GHz radio system. You will have to provide four AA alkaline batteries for the transmitter as well as a battery for the vehicle. There is a wide variety of applicable vehicle batteries, so I'll cover that in more detail a little later.
My first impression while unboxing the TRX-4 was that it is quite heavy. I later weighed it and confirmed that this truck is indeed beefier than my other 1/10-scale vehicles. The TRX-4 comes in at 7.2 pounds without a battery. My other 1/10-scale vehicles average about 4 to 5 pounds. As you will see, the TRX-4 is heavier for good reason.
Even the body is notably heavy. Like most RC truck bodies, it is made of polycarbonate (Lexan). This one comes pre-painted in a 3-tone camouflage pattern. Its extra weight comes from bolt-on scale details such as a spare tire, gas can, and fender skirts.
The good news here is that the TRX-4 is a rock crawler, trail rig, and basher, so a little extra weight is usually no big deal. Once you include the "cool factor" of the features that make this truck big-boned, I doubt you'll mind the extra baggage. It certainly hasn't bothered me.