Vol.6 No.3 June 1998

ISSN: 0971-4413



Combat engineering encompasses vehicles in combat role. Support engineering DEALs with the right type of machine/ equipment for troop movements. It also encompasses a variety of devices, solutions and guiding signals to save valuable human life and equipment under abnormal situations—both man-made and natural. Several technologies have been indigenously developed related to integrated systems, such as tanks, fire fighting systems, military bridges etc; sub-systems, such as power packs, hydraulics, mechanical and structural assemblies etc, and many other materials and components related products.

MBT Arjun

Materials & Products

Structural & Mechanical Systems

Electrical, Electronic & Electrohydraulic Systems

Hydraulics & Pneumatic Systems

Specialised Equipment

Special Purpose Vehicles & Trailers

Fire Fighting & Prevention

Avalanche Prediction & Control

Terrain Evaluation, Simulation & Analysis


Materials & Products

Aluminium Alloy Structures

Weldable and self-ageing aluminium alloy (RDE-40) has been developed for use in light-weight structures. This alloy has shown better stress corrosion resistance than the other alloys in Al-Zn-Mg group. It gives an ultimate tensile strength of 40 kg/sq mm. This alloy is useful for Defence (particularly in the field of aerospace), railways and transportation. The technology has been transferred to industry.

Slewing Ring Bearing

These bearings are large anti-friction bearings which combine the functions of both bearing and gear. They can support loads while facilitating easing rotary motion. Two types of slewing bearing rings have been developed, viz., four-point contact ball slewing ring with split outer ring and single row cross roller slewing ring bearing with internal gears. Now, the indigenous technology base has been created for the slewing ring bearing for which the requirements have so far been met by import only. The slewing ring bearings find use in cranes, excavators, off-shore platform cranes and industrial robots.



Track is required to keep the traction of the vehicle unaffected while the vehicle is mobile even in cross-country terrain operation. The MBT Arjun is fitted with double-pin steel track with detachable rubber pads. It is made out of steel casting having two bores for insertion of rubberised pins. It is an integral piece incorporating guide horns and has got a provision for insertion of detachable pads. The end connectors are induction-hARDEned in the area which comes in contact with the sprocket teeth to prevent wear.

Ballistic Louvers

Ballistic louvers are used in the hull structure of tank. These are configured to give protection against small arms fire and splinters and to provide adequate passage for coolant air to cool the 1500 HP power pack. These louvers are made out of alloy steel. Indigenous source for manufacturing these louvers using special extrusion technique has now been established.


Mini-cored technology has been used for making the oil passage integral with the casing. The casing houses a single input multi-output gear box of 185 KW operating at an input speed of 16810 rpm with an output varying from 6000 to 8000 rpm. It is used for aircraft-mounted accessory gear box and comprises thin walled (5 mm) magnesium alloy (RZ-5) casing with integral oil reservoir and in-built mini cored oil passages.



Pneumatic Assault Boat

The pneumatic boat has two buoyancy tubes made of rubberised nylon fabric. The upper and lower buoyancy tubes have a diameter of 500 mm and 250 mm, respectively. For stiffening the fabric floor, floor panels made of FRP have been provided. The boat is designed to carry 12 men including 2 crew members and is primarily for Defence use. It can also be used to carry men and material during disaster management. It is being produced.

Mountaineering Equipment

To meet the requirements of troops operating in the mountain regions of Himalayan borders, several light-weight mountaineering equip- ment have been developed. The basic material used for these equipment is special cold resistant steel suitable for sub-zero temperature conditions (-50 oC), Al alloys and FRP. Special manufacturing processes have been devised to achieve features like light weight, strength, human comfort, aesthetic appearance etc. Benefits of these developments are now being extended to the mountaineering clubs of the country as spin-offs.



Structural & Mechanical Systems

Military Bridges

Bridge layer tank

A 4 m wide and 20 m long, multi-span assault bridge mounted on Vijayanta tank with fully decked roadway and foldable deck mechanism has been successfully developed. The bridge is compact for transportation and fits in a space of 10.5 m length, 3.5 m width and 3.96 m height. The RDE-40 Al alloy along with innovative geometry have been used to keep it light. The use of high pressure hydraulic drives and actuators in place of electro-chemical drives give advantage of reduced weight. The technology has been transferred to the Services and the bridge is under production.

Epicyclic Gear Box

Epicyclic gear is a concentric drive capable of providing power sustained gear change. It is compact and most suitable for automation. 1500 HP and 150 HP transmissions developed consist of such type of gear trains and are working satisfactorily. Contra rotating concentric drive for torpedo, concentric drive for winch wind mill, and final drive for tracked vehicles are a few examples of epicyclic gear train.

Elevation/Retraction System

Precision elevation/retraction systems have been developed for mobile antenna masts for fast positioning of antennas required for communication systems and air space surveillance. The antenna masts can be mounted on platforms and trucks. Due to special design features and specific manufacturing methods, the deviation from the vertical position at the top of the masts is less than + 10 m which is  a minimum basic requirement for state-of-the-art, advanced transmission and communication techniques. A family of mobile/static masts has  been designed, developed and bulk produced for the Services to meet specific requirements.

Chassis & Automotive Systems (CAS)

Chassis and Automative System of MBT Arjun comprises main chassis, power pack (1400 HP engine coupled to hydromech transmission), running gear with hydropneumatic suspension, integrated fuel system, advanced electrical system and other dedicated special systems like integrated fire detection and suppression system. The chassis is fabricated from rolled homogenous armour plate using advanced welding technique. Frontal armour is of Kanchan composite sandwitched between armour plates. This fully integrated Arjun chassis and Automative System having smooth riding characteristics can be used as a mobile platform for any advanced weapon system.

Automatic Transmission

This transmission has been developed for installation in public service buses. It is fully automatic and provides four speeds forward and two speeds reverse. It consists of modern compounded epicylic gear train and a torque converter with a bypass clutch. This is a spin-off from 1500 HP transmission developed for MBT.



Electrical, Electronic & Electrohydraulic Systems

Rotary Base Junction

Rotary base junctions (RBJs) are intended to be used in AFVs for transfer and distribution of power and control signals from their stationary chassis (like the hull of a tank) to the revolving structure turret of the tank. Therefore, RBJs are required to be very highly reliable and should withstand varying environmental conditions like very high and low temperatures, dust, varying levels of shocks, bumps and vibrations. The RBJs developed indigenously for MBT Arjun weigh approximately 30 kg and provide uninterrupted supply to the turret up to 600 A of load current with a minimal voltage drop.

High Frequency Generators & Tools

High frequency generating sets and tools provide compact and weight-effective solutions to the conventional power generated system and pneumatic tools. This specialised technology has been developed by DRDO for Defence as well as the industry. High frequency generators of 5 KVA and 12.5 KVA sets have been developed to operate with three phase induction motor-driven hand tools required by the troops in the field. These gensets are used to operate HF tools, such as light demolition hammer, rock drill and pressure blower, electric-driven submersible pump, saw and chain etc. The technology has been transferred to the industry for production.

Silent Gen Sets

Two 25 KVA and two 40 KVA silent gen sets with AMF panel both mounted on TATRA vehicles (in pairs), have been designed and developed for defence use. The power system consists of two gen sets housed in two separate acoustic enclosures mounted on single TATRA VVN chassis. The noise level of diesel engines to 72 db A at 1 m from the vehicle from an ambient value of about 90 db A has been achieved.

Touch-Screen Computers & Expert System

The integrated electrolumine- scent touch-screen display controller developed by DRDO provides excellent soldier/machine interface through appealing graphics and touch buttons. It integrates a number of sub-systems via multiple page set-up display diagnostic information through expert system software programmed in the touch-screen dashboard and consumes less power. In addition, an extensive database of a number of sub-systems of MBT can be accessed by the commander and driver through the touch of a button. This system can also be used for civilian applications.



Hydraulics & Pneumatic Systems

Multistage Cylinder

The multistage cylinder with interstate locking is designed to raise the antenna of INDRA radar from 9 m to 18.6 m while mounted with other sub-systems on a mobile platform. The multistage cylinder is operated hydraulically and is provided with interstate mechanical locking arrange- ment to resist the intertube rotation due to wind laod up to 160 km/h. The verticality of the mast is maintained within 30 min up to wind velocity of 100 km/h. This type of multistage cylinder is not readily available in international market. Also, the cost and time involved is prohibitive. This technology has met all the requirements of the users and has been introduced for INDRA II radar systems. A patent has also been filed.

Hydropneumatic Suspension system

An extremely effective hydropneumatic suspension system has been developed for MBT Arjun. The suspension is externally mounted and provides vehicle springing and damping. It consists of one bogey wheel pair for each suspension station. Gaseous medium in the hydropneumatic suspension is for all terrain maneuverability for exploiting the power available. Casing and hub of the hydropneumatic suspension are sealed for preventing dust ingression and water seepage into the casing during operation in marshy area or shallow/medium fording.




Hydraulic Drive

A hydraulic power drive with precise speed control with microprocessor controller has been designed and developed for an airborne application. Precise speed control system from 6 to 7.8 rpm (selectable) with 1 per cent accuracy is obtained through closed loop feedback. The indigenous system is a unique cost-effective solution which has been realised and integrated on the aircraft at a cost of Rs one crore as against the estimated cost of Rs 10 crore for an imported system minus cost of its integration with the aircraft, the constraints for export due to sensitive nature of the exporting country not withstanding.



Specialised Equipment

Controlled Climate Chamber

Controlled climate chamber

Conditions of high altitude and sub-zero temperatures prevalent at high altitude areas and high temperature in desert terrain affects performance of IC engines and IC engine-driven equipment adversely. This test facility has been created to simulate climatic conditions to avoid cumbersome, time consuming and uneconomical trials on equipment at actual site conditions.

Climatic test facility caters to the need of testing the equipment under simulated conditions of altitude (up to 4421 m), temperature (from - 30 oC up to + 55 oC), and humidity (up to 90 per cent).

Dual Control System

Sometimes, for certain tasks, there is a need to drive a vehicle from the rear especially in Defence. Dual control system has been designed for TATRA 8 x 8 VVN vehicle and the contols have been housed in a rear cab. The rear controls are made totally independent and do not affect the front cabin driving controls.


Defence vehicles operate at varying altitudes ranging from sea level to about 5000 m in Himalayas. There is power loss in engine due to low oxygen content in air at high altitude. To compensate for this loss of power, Shaktiman engine was turbocharged and demonstrated to the users. Another necessity for enhancing power of existing UTD 20 (BMP-II) engine was felt for its use in higher GVW vehicles like ASPL (missile carrier cum launcher of 18.5 tonnes), AERV and Dozer. Power increase of up to 20 per cent has been obtained by turbocharging. Very recently, the existing 780 HP engine of T-72 tank has been successfully turbocharged to increase its power to 1100 HP.

Mine Laying System

A new mechanical mine layer for laying not only old types of mines (NDMK1) at a faster rate, but also improved bar type mines has been developed and introduced in service. This anti-tank mine layer Mk II is robust, ruggedised and versatile. It is very popular with the Indian Army.

Angle Position Indicator

DRDO has developed the complete module including the miniature gear box and the necessary mechanical interface required to mount the resolver. The necessary electronics to process the signal for sensing the angular position to an accuracy of +2 milli radian has been developed. Currently, this unit is being used in the tank for sensing turret position.



Special Purpose Vehicles & Trailers

Medical Vehicles

Operation theatre on wheels

Ambulance vehicles have been designed to facilitate quick and safe transfer of patients from an operational area to a base with maximum possible comfort in most difficult conditions. The ambulance has been fabricated on Nissan Patrol and Nissan 1 tonne vehicle chasses. Patient stretchers, emergency medical equipment storage, insulated body etc have been provided in these vehicles.

A mobile blood bank van has also been designed and developed on Nissan 1 Tonne chassis. An ambulance has also been developed by DRDO on track vehicle using the chassis on BMP-II chassis.

In addition, an operation theatre complex on wheels has been developed for providing immeDIATe surgical treatment for the wounded right in the battlefield. This complex comprises five vehicles, namely, operation theatre, pre-operative room, recovery/post-operative room, sterilisation and store room, and a generator vehicle.

Bullet Proofing of Vehicles

The pioneering work of bullet proofing of vehicles like jeeps, light combat vehicles etc has been achieved for the use of special security and similar services to avoid/minimise casualties due to hostile firing from AK-47 or other small arms fire.

The vehicles have been fitted with Jackal armour steel that provides the occupants with complete protection from small arms fire. Wind screen glass provides the same level of protection as the hull. The roof can provide protection from hand grenades lobbed or snipper’s firing atop the building. Layout/configuration of the standard vehicle has been retained.

The engine compartment, raDIATor grill and mud guards are suitably protected from oblique firing or stray bullets. Adequate protection has also been provided to the fuel tank.



Fire Fighting & Prevention

Truck Fire Fighting Large Mk II

Truck fire fighting large Mk II has been developed for the Army and the Air Force on indigenous TATA LPT 1210 E/42 and Ashok Leyland ALCO 4/1 chasses to fight class A as well as class B major fires.

The appliance incorporates a water tank of 2700 l capacity, a foam tank of 350 l capacity, a centrifugal pump to deliver 2250 l/m of water at 7 kg/sq cm, and a monitor capable of delivering 11000 l/min of expanding foam to a distance of 45 m and capable of rotating 360o in the horizontal plane and 75o in the vertical plane. It also includes two side hand lines capable of delivering 7000 l/m of expander foam to a distance of about 25 m.

The appliance has been accepted for introduction in Service. It is being produced by private agencies regularly under the supervision of DGQAE. More than 100 vehicles have been produced.

Integrated Fire Suppression System for MBT Arjun

Fuel-fire-explosion (before and after suppression)

The integrated fire and explosion suppression system developed for MBT Arjun is based on state-of-the-art technology. The indigenous development of this system is considered to be a breakthrough in the field of fire protection engineering. It is capable of suppressing hydrocarbon fuel fire/explosion resulting from an enemy hit on the tank or due to any malfunctioning of the engine, transmission or any electrical short circuiting.

The system is based on infra-red detectors for the detection of fire/explosion in the crew compartment of the battle tank and a continuous type of linear thermal detector popularly known as fire-wire

for the engine compartment. Halon-1301 has been employed as a fire extinguishing medium. The system is capable of detection and suppression of hydrocarbon fuel fire/explosion in the crew compartment within 200 milliseconds and in the engine compartment within 15 s thereby enhancing the chances of survivability of the crew and battle effectiveness of the tank.

Avalanche Prediction & Control

Avalanche Control

Avalanche control structures

Avalanches, natural calamities similar to floods, earthquakes etc, occur in snow bound areas on the slopes claiming a large number of lives and destroying properties worth crores of rupees. However, such avalanches can be controlled through suitably designed control structures. Suitable control structures have been designed to  prevent formation of an avalanche. Some important ones are: erecting suitably designed retaining barriers in the formation zone, channelising the flow of an avalanche by constructing diversion dams/galleries in the middle zone, and retarding the motion of an avalanche by constructing retarding structures like catch dams and mounds in the run-out zone. Terrain information like engineering resources, trafficability potential, obstacles, visibility, camouflage and concealment potential, information on camping ground, advanced landing ground and water supply sources etc is the backbone for land battle. This information is supplied in the form of derivative maps and reports to the Army as well as civilian sector.


Terrain Evaluation, Simulation & Analysis

Mobility Map; Satellite Image; Ground Input

For evaluation of terrain, both aerial photo as well as satellite  data are used. This work has been carried out for both accessible and inaccessible areas of plains, deserts, mountainous terrains and riverine area in western, northern and eastern sectors.

Mobility maps are used by the Army for cross-country movement of tracked vehicles and wheeled vehicles. These maps show spatial distribution of obstacles in terms of going conditions of ground depicted by colour shades of delineated polygons. These maps are commonly known as Going Maps or Trafficability Maps. Preparation of these maps involves updation of base topo maps, either with the help of the latest topo maps or with the help of satellite remote sensing data covering the same area. On the basis of terrain vehicle parameters and ground input, this information is converted into Going Maps.

Geostrategic Analysis

The application of terrain evaluation technology is also employed in geostrategic analysis of inaccessible areas and is incorporated in Area Analysis Studies. Terrain is characterised, analysed and military potential is evaluated after detailed study of reports/maps and remote sensing inputs e.g, aerial photos and satellite data. The latest information is reported in terms of changes in landuse, new obstacles mobility and other relevant details. Entire inaccessible terrain is divided into 20 zones for which individual reports are published every 5 to 10 years of revision period.

Technology has acquired the operational status as upcoming technology like GIS and digital image analysis are also used synergetically to analyse and interpret the minute details of importance, to generate information base and to enhance the derivative map generation capability. This work is being done now on a routine basis for inaccessible terrain across east to west.