4x4 Transfer Case Buying Guide for ARFF and Fire Trucks
4x4 Transfer Case Buying Guide for ARFF and Fire Trucks
Quick answer: A 4x4 transfer case takes the rotation from the transmission and splits it between the front and rear differentials. For an ARFF truck or fire engine on an 8 to 12 ton 4x4 chassis, choose a two-ratio unit whose torque and speed rating covers your engine and gearbox output, with a neutral gear for emergencies, a differential lock for the front wheels, and a mounting and coupling that match your transmission. This guide explains each check in plain steps.
In this guide
- What a 4x4 transfer case does
- Do you need two ratios?
- Neutral gear and differential lock: why they matter
- How to size a transfer case: torque and speed
- Mounting, coupling and lubrication
- Replacing a unit that is hard to source
- How the KTC.900 compares with other units in its class
- Which Kozmaksan transfer case fits your vehicle?
- Common mistakes
- Frequently asked questions
1. What a 4x4 transfer case does
On a 4x4 chassis the transmission has one output, but the vehicle needs power at two axles. The transfer case sits between the shafts, in the middle of the front and rear differentials, and passes the rotation to both. A two-ratio unit adds a fast ratio for the road and a slow ratio for heavy going. The vehicle can also switch between 4x4 and 4x2 driving.
2. Do you need two ratios?
If your vehicle drives on roads and then off them, yes. ARFF trucks cross airfield ground, municipal fire engines reach rough sites and military vehicles work on mixed terrain. The Kozmaksan KTC.900 has two internal ratios, fast and slow: high 1.10 and low 0.56. It also has an idle gear feature. Check both ratios against your tyre size, axle ratio and the ground you expect.
3. Neutral gear and differential lock: why they matter
- Neutral gear. In case of emergency the shafts can rotate freely, so the vehicle's driveline is not locked to the transmission.
- Differential lock. It controls the drive to the front wheels.
- Differential system. A differential system can also be added to the KTC.900.
Ask for these features at the order stage. They are far easier to specify than to add later.
4. How to size a transfer case: torque and speed
Start from the engine and gearbox, not from the vehicle name.
- Find the maximum torque and speed that reach the transfer case input.
- Compare them with the transfer case ratings. For the KTC.900, maximum continuous torque at the main drive is 6000 Nm (4425 lb-ft) and maximum speed is 5300 rpm.
- Check the differential output. The data sheet gives 9000 Nm at the shaft and 5830 rpm.
- Leave a safety margin for heavy duty and emergency use.
| KTC.900 data sheet figure | Value |
|---|---|
| Main drive, max continuous torque | 6000 Nm / 4425 lb-ft |
| Main drive, max instantaneous torque | 5800 Nm |
| Main drive, max speed | 5300 rpm |
| Differential output, max torque at shaft | 9000 Nm |
| Differential output, max speed | 5830 rpm |
| High / low drive ratio | 1.10 / 0.56 |
5. Mounting, coupling and lubrication
- Coupling. The KTC.900 can be coupled directly with Allison 1000 and 2000 series transmissions.
- Space. The front view drawing is 670.5 x 435 mm. Check the clearance on your chassis.
- Oil. Oil capacity is 8.5 L in vertical assembly. A lubrication pump and oil indicator plug are shown on the data sheet, and the vent plug thread is M14x2.
- Controls. Control sensors are available for 4x2-4x4, high, neutral and low modes, plus an rpm counter and a 4x2-4x4 air control gland.
6. Replacing a unit that is hard to source
Older transfer cases can be difficult to find. To confirm that a replacement fits, send us:
- The nameplate or a photo of the old unit
- Ratios and flange types
- Mounting and output dimensions
- Transmission model
- The control sensors and options you need
- Your delivery country
7. How the KTC.900 compares with other units in its class
Buyers often compare 6000 Nm class aluminum two-speed transfer cases. One published example is the Meritor MTC3205 series, listed by Cummins under the legacy names RTC-25 and MTC-25. Both it and the KTC.900 are rated at 6000 Nm (4425 lb-ft) and 5300 rpm and use an aluminum housing. The KTC.900 includes the neutral gear, idle gear and differential lock, and couples directly with Allison 1000-2000 series transmissions. Each manufacturer states its figures under its own conditions, and ratio notation differs, so always confirm mounting, flanges and ratios for your vehicle before you order.
8. Which Kozmaksan transfer case fits your vehicle?
The KTC.900 is one of several Kozmaksan 4x4 transfer cases. Choose by vehicle weight class, torque and the job the vehicle does.
| Model | Vehicle class and use | Max torque | Key points |
|---|---|---|---|
| KTC.900 | 8-12 ton medium-duty 4x4; ARFF, fire fighting, military vehicles | 6000 Nm continuous (main drive) | Two ratios, idle gear, neutral gear, differential lock, direct coupling to Allison 1000-2000 series |
| KTC.3000 | Extra heavy-duty 30-40 ton 4x4; heavy-duty trucks, mining vehicles, fire fighting trucks | 19000 Nm | Switches between 4x4 and 4x2, internal ratio 1/1 |
| KTC.302 | Off-road vehicles and railway line maintenance vehicles | 1700 Nm | Differential lock, PTO output, split shaft mounting, pneumatic control, aluminium body, 80 kg |
| KTC.301 | Off-road vehicles and railway line maintenance vehicles | 1700 Nm | Differential lock, split shaft mounting, pneumatic control, aluminium body, 68 kg |
Need power at three axles? See our 6x6 transfer cases: KTC.6000 for ARFF trucks and KTC.6001 for heavy duty trucks. You can also browse the full Kozmaksan transfer case range.
9. Common mistakes
- Choosing by vehicle name instead of by torque and speed at the transfer case input
- Skipping the ratio check against tyre size and axle ratio
- Forgetting the neutral gear, differential lock or sensors at the order stage
- Not checking the clearance and mounting position on the chassis
- Ignoring the oil capacity for the way the unit is mounted
10. Frequently asked questions
What does a 4x4 transfer case do on a fire truck?
It splits the transmission output between the front and rear differentials and lets the driver choose a fast or slow ratio.
What weight class is the KTC.900 designed for?
8 to 12 ton capacity medium-duty 4x4 rubber-tired vehicles.
Which transmissions does it couple with?
Allison 1000 and 2000 series transmissions, directly.
Does it have a neutral gear?
Yes. In case of emergency the shafts can rotate freely.
Can I switch between 4x4 and 4x2?
Yes. The KTC.900 switches between 4x4 and 4x2 driving.
Which sensors and options are available?
Rpm counter, high mode, neutral gear, low mode and 4x2-4x4 control sensors, a 4x2-4x4 air control gland, oil indicator plug and lubrication pump.
Which vehicles use it?
ARFF trucks, fire fighting trucks and military vehicles are the listed applications.
What if my vehicle is heavier than 12 tons?
See the KTC.3000, designed for extra heavy-duty 30-40 ton rubber-tired 4x4 vehicles with 19000 Nm maximum torque, or tell us your vehicle and we will recommend a model.
Do you make transfer cases for off-road and railway maintenance vehicles?
Yes. The KTC.301 and KTC.302 are made for off-road vehicles and railway line maintenance vehicles, with a differential lock. The KTC.302 also has a PTO output.
Do you make 6x6 transfer cases?
Yes. See the KTC.6000 for ARFF trucks and the KTC.6001 for heavy duty trucks.
Do you ship worldwide?
Yes. Send your chassis details and delivery country for a quote.
Next step
Ready to specify? See the product page, download the KTC.900 data sheet and request a quote: 4x4 Transfer Case for ARFF and Fire Fighting Trucks. Looking for another vehicle class? Browse the full Kozmaksan transfer case range.
Technical figures are from the Kozmaksan KTC.900 data sheet, Rev. 01 (11/2022). Meritor and MTC are trademarks of their owners; the MTC3205 figures come from the manufacturer's published information and are shown for comparison only.
