4 wheel drive is a system in wich all 4 wheels are driven. These trucks are often equiped with long travel supension. In this article I hope to explane, to the best of my ability, the diferences between diferent drive systems and styles of suspension. Any input you have for me would be greatly apreciated as I know that my information is far from compleete.
In RC there are 4 common ways to connect the motor(s) to the front and rear drive systems. In most trucks there is a single 540 electric motor. Larger trucks often use 2 motors to get more torque.
The 4 main types of Radio Control 4 wheel drive systems:
Single Motor Rear Wheel Proprietary
The motor is connected to the rear gearbox. A drive shaft of belt then conects the rear
gearbox to the front gearbox.
Advantages-This system is simple for companies to build as it is easier to rout steering rods.
Disadvantages-This system has a problem with what is known as "understeer" or "push". This means that it doesnt like to turn as sharp at high speed. Also they spin out easier due to the fact that the rear wheels start spinning a split second before the front.
Single Motor Front Wheel Proprietary
This is the oposite of Rear Wheel Proprietary in that the motor is connected to the front
gearbox with a shaft or belt connecting the front gearbox to the rear gearbox.
Advantages-Since the front wheels engage before the rear traction is more positive. Turning radius is smaller than other types of drive systems. Trucks also tend to climb better without lifting the front tires.
Disadvantages-There is often less room for steering in this type of truck as the motor and the steering have to occupy the same space. More often than not the steering engineering seems more like an afterthought and isnt very strong or is sloppy. Note that this isnt a rule of thumb as there are more than likly quite a few trucks that have well engineered steering. Anothar problem is that these trucks tend to be front heavy and want to nose wheely on sudden braking and reverse.
Dual Motor Independant
This is the most unrealistic and ineficient drive system but is the most common among
larger trucks like monster trucks. In this system there is one motor in the front gearbox and
one motor in the rear gearbox with nothing connecting the 2 gearboxes together.
Advantages-Simplicity, no drive shafts or belts to wory about breaking sliping or stripping. As well as the ability to limp off the trail in 2 wheel drive if something should break.
Disadvantages-Traction is inconsistant as the front and rear wheels can spin at different rates. Often the front gearbox requires a reversed motor, limiting your choice of motors as many cannot be reversed.
Single or Dual Motor Proprietary
Often these are the most realistic form of drive system. The motor(s) is/are connected to a
single central gearbox. From that central gearbox one driveshaft goes back to the rear gearbox
and anothar goes forward to the front gearbox.
Advantages-Very consistant traction in forward and reverse. Front and rear gearboxes are often identical making parts cheaper and easier to get.
Disadvantages-Often these systems have a high center of gravity due to the central gearbox being placed high in the chassis to increase ground clearance. Often they are prone to mild understeer at high speed. This is a very minor problem though.