From BeamNG

The automatic gear box (device name "automaticGearbox") is a model of an automatic transmission including a one way hill holding viscous clutch, and a parking lock. Unlike a manual gearbox, the auto shifts smoothly between gears. In a Powertrain it is designed to be placed behind a viscousClutch or torqueConverter only, and should have a shaft, differential, rangeBox or splitShaft connected to it.

Jbeam Properties

Name Type Optional Default Value Description
gearRatios array false na This array is the list of gear ratios available to the gearbox. 0 represents neutral. A negative number indicates a reverse gear. The gearbox will have as many gears as specified in the array. Ex "gearRatios":[-3,-2,0,4,3,2,1,0.5] has 5 forward and 2 reverse gear ratios.
oneWayViscousCoef number true 5 This value controls how stiff the hill holding viscous clutch is. A higher value will make the vehicle less likely to creep backwards on a hill.
oneWayViscousTorque number true =onewayViscousCoef*20 The upper limit for hill holding torque, used for stability reasons.
parkLockTorque number true 1000 The upper limit for the parking lock torque. If exceeded, the parking lock will slip.
parkLockSpring number true Auto calculated The stiffness of the parking lock spring. Too high may cause instability.
friction number true 0 The friction torque applied to the input side of the gearbox.
shiftEfficiency number true 0.5 The max proportion of torque loss during the shift.
gearChangeTime number true 0.5 The time taken to smoothly shift from one gear to the next.


Here is an example of the required powertrain section, along with the additional section for the properties.

    "powertrain": [
        ["type", "name", "inputName", "inputIndex"],
        ["automaticGearbox", "gearbox", "torqueConverter", 1],
    "gearbox": {
        "gearRatios":[-2.27, 0, 2.79, 1.54, 1.00, 0.695]
        "friction": 1,