Driving a split-shift dual transmission vehicle is not easy, but once you get the hang of it, the ride is very smooth. Split-shift rear-axle gear systems were designed for vehicles that require a great deal of torque to carry heavy loads and that is why they are popular in dump trucks and semi-tractors. Split shift systems are popular because the large number of gears prevent the truck from lurching every time you shift carrying a heavy load.
Put both transmission boxes in "Neutral." Fire-up the vehicle and put your foot on the brake. Release the air brakes. Engage the clutch and put the primary transmission box in first gear. Put the auxiliary transmission box in first gear as well.
Release the clutch slowly and allow the gears to engage. Moving forward, place your foot on the accelerator and bring your tachometer's revolutions per minute up to a suitable shifting speed. Push the clutch to the floor, release it, and push it to the floor again. Move the auxiliary gear stick into second gear and release the clutch. You are now in second on your auxiliary, but your primary gear box is still in first. Follow this process through your remaining two auxiliary gears, third and fourth.
Raise your rpm to a suitable shifting speed and double-pump the clutch, holding it down on the second pump. Put your auxiliary box in "Neutral" and shift your primary transmission box into second gear. Slide the auxiliary box into first gear and release the clutch. You just performed the act of split shifting.
Shift through the gears of your auxiliary box until you reach fourth gear, then clutch the transmissions, neutralize your axillary box and move the primary transmission box into third. Move through the gears of your auxiliary box until you reach fourth gear then neutralize your auxiliary box and move the primary into fourth and begin moving through your auxiliary box again. You just successfully ran through the gears of a split shifter.
