Putting one of the army’s workhorses to test

A few weeks ago when the Rafale controversy was still on the boil and there was more action due along the border, I thought it might be interesting to experience a defence vehicle that is currently serving the armed forces. Something a little over the top, and yet very raw and essential for delivering supplies deep into the conflict zone, Ashok Leyland’s FAT 6X6 seemed like the kind of vehicle that would fit the bill perfectly. There was even more symbolism than I had expected being as it was right in the middle of a Bofors style controversy.

What is it?

Called the Field Artillery Tractor or Truck, this is an all-terrain, common gun-tower vehicle platform that has been created exclusively for defence purposes and is supplied to the Indian Army for transporting heavy guns such as the Bofors howitzers. The truck has a total towing capacity of 12-18 tonnes. I travelled to Ashok Leyland’s test track just North of Chennai, which would have been the only place where I could have legally driven the multi-axle truck. My test mule was the truck/tractor, which with its camouflage livery is supplied as a combination with a self-recovery winch at the front with a pulling capacity of 10 tonnes. At the rear, mounted on a second cabin, is a crane for loading and unloading ammunition into the gun that is being towed. The crane itself weighs a little more than 2.5 tonnes and the GVW (gross vehicle weight) including the crane is a massive 22 tonnes.

Getting into the FAT 6X6 is quite a climb and when I take the driver’s seat, it feels almost like I’m seated on a chair at the mezzanine floor of a building. The cabin is spartan but with controls bunched up on a curved inward dashboard. There are none of the plastic panels that we see in mass market cars; here they have been replaced with riveted steel panels and chunky switches and knobs, all of which are focussed on rugged build, and easy repair and replacement. The massive instrument cluster has multiple gauges including speedometer, odometer, fuel, temperature and oil gauges and tyre pressure dials. The dashboard also has a digital display bolted on at the top, which throws up a live image fed by an infrared rear camera to constantly monitor the gun coupling and movement of the gun being towed.

The front passenger side of the dashboard houses a chunky, old-world style military-green telephone instrument in its cradle, very reminiscent of the war movies we have all seen. This is part of the inter-communications system between the driver cabin and the crew cabin. The driver cabin has two-plus-three seats and the rear cabin has six seats and two berth beds. It also has an in-built fire detection unit to prevent any potential self-generated fires. Also part of the equipment within the cabin is air-conditioning, what we take for granted and what may be extremely essential for Desert Ops given that it is a soft-top.

Performance

The FAT 6X6 is powered by Ashok Leyland’s N360 (Neptune) Diesel engine that delivers a peak power of 360 hp and torque of 1,400 Nm. This BS III compliant diesel engine is paired with an eight-speed manual transmission, with a two-speed auxiliary gearbox for high and low speed operations and for handling difficult terrain such as steep gradients and slippery or sandy conditions. Crank the engine and its diesel character comes through strongly, though vibration level at the gearstick and the steering wheel is surprisingly low. There are big dollops of torque from low rpms and getting the mammoth to move quickly off standstill is not much of a problem. Power peaks out pretty early with the optimum rpm band being quite narrow. The redline is set at 2,500 rpm. Consistent throttle input and a quick shift up the gears gets the FAT 6X6 into a nice rhythm around the test track. Top speed is limited to 90 kmph.

The truck has a full time six-wheel drive system with a differential lock at each of the three axles. It features reduction gears in two places — hub-end and axle differential. One of the special features in the FAT 6X6 is the CTI (central tyre inflation) system for changing the level of tyre inflation based on operations on different terrain. The fuel tank capacity is 350 litres and there can be a little extra that can be stored in jerry cans for safety purposes. But, the operational range is about 700 km. The winch and crane are operated by PTO (power take off) from the gearbox.

The suspension is parabolic with shock absorbers for the front, and at the rear they are inverted bogies (underlying for both are leafsprings). Essentially, the set-up is focussed on simple engineering that can be easily repaired on the go, while also offering enough strength to handle the high payload needs of the platform. The ride quality is certainly not at all like a passenger car, but it is not too harsh either. The FAT 6X6’s ability to swallow anything on its path though is phenomenal. Rocky paved blocks, massive obstacles replicated by speed breakers and sharp features on the road shake up the cabin a bit, but the truck is unruffled and literally bulldozes over all of them.

It won’t be stuck in a spot either with its mechanical differential locks that can be operated from the driver cabin using electromagnetic solenoids. The torque split is a standard 33:67, but with the AGB differential lock engaged, it can be an equal split between the front and the two rear axles. It can handle 30-degree degradability.

The Ashok Leyland FAT 6X6 truck is produced specifically for the armed forces and is an indigenously developed solution for replacing the imported towing trucks that were being used earlier. The first batch was delivered to the Indian army in 2017.

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