Super Select is the brand name of a four-wheel drive system produced by Mitsubishi Motors, used worldwide except for North America, where it was initially known as Active-Trac. It was first introduced in 1991 with the then-new second generation of the Mitsubishi Pajero.
The system offers a choice of four rear- or four-wheel driving modes with both high and low ranges, selected using a lever mounted alongside the gear shift lever, both in motion or stopped (depending on the mode to be selected).
The system differs significantly from 'traditional' 4WD systems in that it offers more driven-axle modes in both high and low ranges than most other part-time systems on the market. The system features 4 modes: 2H, 4H, 4HLc and 4LLc. On early models, a neutral position for the transfer case was also selectable.
Modes
2H: 2WD, high range. 100% of available power is sent to the rear axle.
4H: 4WD, high range. Power is sent to both the front and rear axles while the centre differential remains unlocked.
4HLc: 4WD, high range, locked centre differential. Power is sent to the front and rear axles with the centre differential locked, ensuring that a percentage of power is still sent to the forward axles even if a rear wheel is spinning (and vice versa).
4LLc: 4WD, low range, locked centre differential. Power is sent to the front and rear axles with the centre differential locked, ensuring that a percentage of power is still sent to the forward axles even if a rear wheel is spinning (and vice versa) however the gearing ratio is doubled, increasing torque by more than 2x and reducing speed in each of the gears by the same factor.
Usage
2H is intended for normal daily use around town for better fuel economy and where loss of traction is not a concern. Mitsubishi (like other manufacturers) does not recommend that 2WD be used when towing as it can cause excessive heat and wear on the differential.
4H is intended for use on gravel, wet roads, snowy or dusty conditions. In fact Mitsubishi recommends this mode for almost all situations due to the enhanced handling and safety and lower drivetrain strain when towing. Unlike many part-time 4WD systems, 4H can be used on tarmac and hard surfaces without the risk of damaging the transfer case through gearbox windup (excessive, uneven torque applied to the transfer input/output shafts through the difference in rotation speeds of each wheel when on a high-grip surface that cannot relieve this through slippage on the terrain itself). 4H can be used in moderate off-road situations where extra traction is desired, however as the centre differential remains unlocked, a single slipping wheel will result in power being fed to that wheel, halting forward progress (unless other traction aids are used). Depending on the version of Super Select, the operator can shift between 2H and 4H at speeds of up to either 80km/h or 100km/h.
4HLc is intended for high speed operation (~50km/h) in more challenging terrain such as mud, fording water, rutted or off camber terrain and snow where low speed operation is not necessary or possible. This mode is not to be used on tarmac and sealed surfaces due to the centre differential being locked.
4LLc is to be used for extreme off-roading <30km/h. This doubles torque sent to the wheels while halving the speed. This mode is to be used in deep mud, rock climbing, steep hills, deep ruts, heavy snow and recovery situations. Not to be used on tarmac and sealed surfaces.
System Operation and Mechanics
In early versions of Super Select such as found in the Generation 2 Pajero, transfer-case neutral can be selected. On later models (Generation 3 and up) this is not an option, only transmission neutral.
Shift operation in early version is done through a gated lever. Beginning in 2H at the rear-most position, the operator can push one notch forward into 4H without any lockout. To select 4HLc, the operator then pushes the lever sideways and forward into 4HLc, also without lockout. In this position 4LLc is locked out. In order to shift into 4LLc, the operator pushes directly downward on the lever to bypass the lockout and forward into the 4LLc position. To return, the operator simply pulls backward on the lever, no lockout needs to be bypassed.
In newer versions of Super Select such as in Generation 4 Pajeros, there is a straight forward/backward travel with lockout on every position. The operator simply presses down and slides the lever forward into the desired position and does the same to return.