Gearbox for MB-Trac 800-1300

Hello there,

just wanted to drop by a "real" configuration for the larger MB Tracs. The 800-1300 series used a very unique transmission with multiple gear levers for different speeds. The gearbox was taken from the Unimog models and went through a couple of modifications.

The MB Trac transmission works a lot different than i.e. a Deutz/IHC/Fendt. I would go as far and say that this gear system is pretty hard to drive, but if you manage to understand how it works it's a very good one, considering the MB Trac has no powershift. You can essentially drive "half gears" and get much better traction results than with other tractors.

Here's how it works:

There are multiple gear levers, depending on the selected gearbox up to 5(!) in total.

Picture: (this transmission is for geartype "2". Note that the gear numbers for reverse are from an older version of the gearbox. With release of the newest Trac generation they introduced the shuttle control, allowing to drive all gears in both directions.)

1) Main gear lever - a regular H-shifter with 4 positions + neutral. Can shift gears 1-4 (pre selection range 1) and 5-8 (pre selection range 2) 2) pre selection - changes the main gears from 1-4 to 5-8 3) shuttle control - swaps between forward and backward gears 4) Crawl gear range - additional range for slow/very slow speeds (not used in this gearbox right now, but I'll work on them in the future. In the picture they're gearbox config 3 and 4.

I spent quite some time to evaluate how it actually works in real life, and I think I have a smooth working version ready by now. I included a 40km/h and a 30 km/h version. The main difference between both is that with the 30 km/h version, gear 7 and 8 are locked in the road range, while with the 40km/h version only gear 8 is locked, along with slightly different speed for each gear.

The gears are shown as following:

gear 1/5 gear 2/6 gear 3/7 (gear 7 locked for 30km/h version) gear 4/8 (gear 8 locked for 30 and 40km/h version)

Pre selection is indicated this way:

Gears 1-4 : x/- Gears 5-8 : -/x

And here are some ingame examples how it looks:

Gear 2 (work group): fsscreen_2018_05_21_01_51_40

Gear 5 (work group): fsscreen_2018_05_21_01_51_26

Gear 7 (street group) fsscreen_2018_05_21_01_59_58

Gear 4 (street group) fsscreen_2018_05_21_01_59_51

Gear 7 (backward - street group) fsscreen_2018_05_21_02_00_07

30 km/h version, gear 1 and 5 (as you can see the H shifter is still in gear 1, but you get gear 5) fsscreen_2018_05_21_02_30_37

fsscreen_2018_05_21_02_30_42

30km/h and 40 km/h version for the MB Trac 1100:

Usage: You can pre select the range with shift + "#/+" keys (for gears 1-4 and 5-8) and shift those gears with the normal H-shifter. The regular groups (work group/street group) are selected with "#/+" keys as normal. Note that gear 7 is locked for the 30km/h Trac and gar 8 is blocked for both 30km/h and 40km/h versions.

You can start off using gears 3-5 (depending on how much load the Trac has to pull) with decent success in road group.

Pre selection is used with manual clutching. In reallife the shifting process can be very abrupt if you try to switch the pre selection while under load/high engine rpm.

Shuttle control (R) allows to drive each gear in forward or backward direction. In real life switching direction requires the vehicle to stand still.

# # <transmissions>
        <transmission name="40 km/h" speedLimiter="true" showHud="true" ptoRpm="2000" clutchEngagingTimeMs="500" maxForwardSpeed="72" maxBackwardSpeed="28" maxAIRange="3" autoStartStop="false">
            <gears defaultGear="3" shiftTimeMs="700">   
                <gear speed="6.1"   name="1/5"/>
                <gear speed="8.4"   name="2/6"/>
                <gear speed="11.5"  name="3/7"/>
                <gear speed="15.7"  name="4/8" maxRange2="1" />
            </gears>

            <ranges defaultRange="2" shiftTimeMs="900" reverseReset="false" >
                <range ratio="0.313"  name="A" />
                <range ratio="1"  name="S" />
            </ranges>

            <ranges defaultRange="1" shiftTimeMs="1400" doubleclutch="true" >
                <range ratio="1" name="x/-" />
                <range ratio="3.607" name="-/x" />
            </ranges>
            <reverse ratio="1.03" shiftTimeMs="900" manualClutch="false" doubleclutch="true" 

resetRange="false" resetGear="false"/>
        </transmission>
        <transmission name="30 km/h" speedLimiter="true" showHud="true" ptoRpm="2000" clutchEngagingTimeMs="500" maxForwardSpeed="72" maxBackwardSpeed="28" maxAIRange="3" autoStartStop="false">
            <gears defaultGear="3" shiftTimeMs="700">   
                <gear speed="6.29"   name="1/5"/>
                <gear speed="8.74"   name="2/6"/>
                <gear speed="11.92"  name="3/7"maxRange2="1"/>
                <gear speed="16.25"  name="4/8" maxRange2="1" />
            </gears>

            <ranges defaultRange="2" shiftTimeMs="900" reverseReset="false" >
                <range ratio="0.3132"  name="A" />
                <range ratio="1"  name="S" />
            </ranges>

            <ranges defaultRange="1" shiftTimeMs="1400" doubleclutch="true" >
                <range ratio="1" name="x/-" />
                <range ratio="3.622" name="-/x" />
            </ranges>
            <reverse ratio="1.036" shiftTimeMs="900" manualClutch="false" doubleclutch="true" resetRange="false" resetGear="false"/>
        </transmission>
    </transmissions>
        <realEngine idleRpm="800" ratedRpm="2400">
            <torque rpm="350"  motorTorque="224" />
            <torque rpm="700"  motorTorque="297" />
            <torque rpm="900"  motorTorque="320" />  
            <torque rpm="1000" motorTorque="330" />
            <torque rpm="1100" motorTorque="339" />
            <torque rpm="1200" motorTorque="346" />
            <torque rpm="1300" motorTorque="352" />
            <torque rpm="1400" motorTorque="357" />
            <torque rpm="1500" motorTorque="360" />
            <torque rpm="1600" motorTorque="362" />
            <torque rpm="1700" motorTorque="363" />   
            <torque rpm="1800" motorTorque="360" /> 
            <torque rpm="1850" motorTorque="359" /> 
            <torque rpm="1900" motorTorque="357" /> 
            <torque rpm="1950" motorTorque="355" /> 
            <torque rpm="2000" motorTorque="353" /> 
            <torque rpm="2050" motorTorque="350" />
            <torque rpm="2100" motorTorque="348" /> 
            <torque rpm="2150" motorTorque="345" /> 
            <torque rpm="2200" motorTorque="342" /> 
            <torque rpm="2250" motorTorque="339" />
            <torque rpm="2300" motorTorque="336" /> 
            <torque rpm="2350" motorTorque="329" /> 
            <torque rpm="2400" motorTorque="322" />             
            <torque rpm="2450" motorTorque="281" />             
            <torque rpm="2500" motorTorque="158" />
            <torque rpm="2550" motorTorque="0" />                       
        </realEngine>

Mogli12 / GearboxAddon

Gearbox for MB-Trac 800-1300 #378