The 155 mm TIG 2000 gun-howitzer family were originally developed by Soltam Systems as a private venture and is a follow-on to the earlier Soltam Systems Model 839/839P and Model 945/945P towed gun-howitzers. The P in this designation means that it is fitted with an auxiliary propulsion unit (APU).

In the designation TIG 2000, the TIG stands for Towed Independent Gun. According to Soltam Systems, the TIG 2000 is unique in that it can be fitted with a 155 mm 39, 45 or 52 calibre ordnance by the replacement of the barrel assembly and towing rod only. This can be accomplished at field level.

The TIG 2000 can be supplied as a conventional towed artillery system or fitted with an APU. In both cases the system can be operated by a crew of four people.

It is fully air-transportable in aircraft such as the Lockheed Martin C-130 and the model with an APU can enter and leave the aircraft under its own power.

The Slovenian company RAVNE has also been involved in local production of the 155 mm Soltam Systems towed artillery systems. The Slovenian 155 mm 155/45 calibre model is not fitted with an APU.

The TIG 2000 has a conventional split carriage and when in the travelling position the 155 mm/52 calibre barrel is traversed through 180° and locked in position over the closed trails.

The 155 mm ordnance conforms to the Joint Ballistic Memorandum of Understanding (JBMoU) and is of the monoblock autofrettaged type forged from high-strength steel. The ordnance is fitted with a muzzle brake and a fume extractor.

The breech ring mechanism consists of the breech ring assembly, breech block assembly and the automatic breech block operating mechanism.

The cradle, pivoted to the saddle by the trunnions, carries all parts of the gun which participate in recoil as well as in the vertical movement during elevation and depression.

The central part of the cradle carries the barrel assembly. On top are the recuperator cylinders and at the bottom, the buffer cylinder and elevating arc. At its lower ends are the trunnions, left and right and at its front end, the hinges for the equilibrators. The recoil length cut-off gear is located at the lower right front end of the cradle.

The recoil mechanism consists of a hydropneumatic recuperator, hydraulic buffer and recuperator and a mechanical recoil length cut-off gear.

Two equilibrators, energised by compressed gas, act as self-adjusting force, balancing the barrel, to allow for each laying and adjusting in elevation and depression.

The mount includes the saddle, which carries the ordnance and enables laying in elevation and azimuth. The mounts main assemblies are saddle, elevating and traversing mechanisms.

The saddle is a welded construction that is bolted to the bearings rotating part in the bottom and carrying the cradle. The elevating and traversing gears are mounted on the saddle with the gunner's controls being on the left side.

The elevating mechanism comprises a number of gears incorporating worm and worm wheel with the complete mechanism being fitted on the left side of the saddle.

The traverse mechanism is mounted on the forward part of the saddle and serves to lay the gun in azimuth. A total deflection of 75° (1,334 mm) is possible without shifting the gun.

For fast deflection or when rotating the barrel from the firing position to the travelling position, or vice versa, the mechanism can be disengaged, using a quick release clutch allowing free lateral movement of the barrel.

The carriage serves as the weapon's main support in action and transport. It also carries all of the auxiliary systems that are required for operating the Soltam Systems 155 mm TIG gun-howitzer.

The main carriage assemblies are the central structure and main bearing, firing platform and jack, trails and towing rod assembly, running gears and walking beam, braking system, spade assemblies, support wheels and the electrical system and installation.

The central structure serves as the backbone of the whole weapon and is of all-welded steel construction carrying on its top the main bearing. On the underside is the firing jack with firing platform and on each side is a trail with running gear. On the front part of the structure is the electric battery and hydraulic controls compartment.

The main bearing is of the slewing wire, heavy duty type. The lower and upper rings of the bearing are stationary and bolted to the central structure.

The central bearing ring carries the saddle and by means of a traversing gearbox, mounted on the saddle and being engaged with the bearing ring, allows traversing of the weapon in relation to the carriage.

The firing jack with its associated platform serves two purposes. First, to assure stability of the gun when it is firing with the gun resting on the platform at the front and spades at the rear. Second, to allow for the spreading and folding of the trails when the gun is brought into and out of action.

The jack is operated hydraulically by the APU or by a back-up electric pump powered by the batteries. Should the electric system fail then the jack will be operated by the manually operated hydraulic pump.

The trails also carry the APU (left trail) and associated systems including braking system, support wheels, spades, towing rod, travelling clamp and the rammer's pressure bottle.

Both trails are fitted with fixtures and mounts to carry the different accessories required to operate the gun. Handles are provided at the rear of each trail to facilitate movement of the weapon, this is in addition to sockets in each trail in which lifting rods can be inserted.

Standard size, four (two either side) running wheels that incorporate hydraulic motors in their hubs are mounted on walking beams for road and cross-country use. Each individual wheel incorporates a disc brake with two braking callipers.

The system is fitted with a hydro pneumatic braking booster, which is energised by NATO standard dual-line pneumatic connections. The braking system, built into one of the howitzer's trails, incorporates an emergency pressure tank.

In ordinary operation, the howitzer's brakes are automatically applied simultaneously with the towing vehicle's brakes by the driver's pedal. In case the howitzer and pneumatic lines become disconnected from the towing vehicle, the howitzer's brakes are automatically activated, stopping the gun.

To support the gun against horizontal firing loads two self-digging spades are used. When travelling, the spades are carried on each trail at its rear and when required for action fold down. In this position, a special dual-purpose mechanism locks and secures the blade. The same lock is used for holding the blade in the travelling position.

One support wheel is located on each trail on the outboard sidewall. The wheels serve for supporting the gun while travelling as well as spreading and folding the trails when coming into and out of action.

The electrical system comprises two 24 V, 120 Ah batteries as a power source, 24 V DC series motor driving a hydraulic pump, electronic controller for operating the pump motor and monitoring the battery charge state, lighting and signalling system and an electrical harness connection to the towing vehicle.

The TIG 2000 is fitted with a loading tray which incorporates a pneumatic ramming piston enabling uniform loading of the projectile into the barrel chamber at all angles of elevation without the need to lower the barrel.

According to Soltam Systems, the weapon imposes no limitations on the towing vehicles speed when being towed. Its low centre of gravity, overall length and the tandem wheels mounted on the walking beams assure smooth riding at all speeds, bends and rough terrain. The APU fitted to the towed independent version does not influence the towing properties in any way.

The automatic horizontal sliding breech mechanism, fume extractor and wide angle of traverse, together with the loader assist device, enable effective high rates of fire to be achieved. The load-assist device transfers projectiles from the supply truck, or from the ground, to the loading tray of the howitzer. A manual back up is provided in case there is a power failure.

In the TIG 2000 fitted with the APU, the latter provides power not only for driving the howitzer but also for bringing it into and out of action. It also assists in preparing the howitzer for the transport mode and for ammunition hoisting.

The driver of the APU has a control lever of the joystick type, which controls direction and speed, other controls include starter, speed range selector and parking brake.

By pushing the lever to the desired direction the system moves in that direction, as soon as it is released it returns to the neutral position and the weapon comes to a halt.

As this version can move in any direction up to 17 km/h, it can enter firing positions that could not be reached if the APU was not fitted.

The driver's seat and console are located on the left side of the howitzer and when deployed in the firing position, the driver's console is folded downwards. The system can be manoeuvred from the driver's seat or from the ground with the operator walking alongside the gun.

The hydraulic power supplied from the APU powers the howitzer through hydrostatic motors incorporated into the four, (two either side) driving wheels. In addition, it lifts the howitzer off the wheels onto its firing platform, operates the auxiliary jack to hook or unhook the howitzer from the towing vehicle, spreads the trails and afterwards undigs the spades.

In the conventional towed version of the TIG 2000, an assistance hydroelectric power unit is installed to ease crew member's tasks.

The TIG 2000 can be used in the direct and indirect fire roles and to achieve these two objectives, separate sighting systems are installed. The main sighting system is intended for long-range fire with the secondary system serving for the direct fire role, especially self-defence. The sights are mounted on the left side of the TIG 2000.

The TIG 2000 can also be linked to any artillery command, control and communication system.

In place of the conventional indirect laying system, an Advanced Laying Instrument (ALI), based on ring laser gyro techniques, can be fitted. This also provides options for North Finder, GPS and navigation modules.

Further development of the 155 mm TIG gun-howitzer family by Soltam Systems has resulted in the 155 mm Autonomous Towed Gun ATHOS 2052 (the last two digits [52] stand for the length of the barrel in calibres).

In addition to being fitted with an APU, ATHOS 2052 is also fitted with an automatic laying mode which is integrated with a fully computerised system to enable automatic control, accurate navigation and target acquisition.

Standard equipment on ATHOS 2052 includes a flick rammer, GPS and onboard firing computer. It can receive digital radio target data directly from the forward observer or from the target acquisition system and fully automatic laying is possible. A muzzle velocity radar can be installed on the barrel if required. This could feed information into the fire-control system.

Two 12 V batteries are provided and these are charged when the gun is towed or by the diesel engine of the APU. These batteries provide the power necessary for the various electronic devices and also allow the use of an electro-hydraulic pump for silent operation.

According to Soltam Systems, the hydraulic system installed on ATHOS 2052 enables easy deployment of the weapon using hydraulic jacks and auxiliary wheels. It requires a crew of four to six people to fully operate the system.

To reduce crew fatigue, an ammunition loader assist is installed. The weight of ATHOS 2052 is quoted as 13,000 kg.

In addition to being marketed in 155 mm/52 calibre it is also being marketed in other calibres such as 155 mm/39 and 155 mm/45.

This is a self-propelled version of ATHOS and is normally installed on a 6 × 6 or 8 × 8 truck chassis. This is already in production for an undisclosed export customer and full details are given in a separate entry. Recent information is that these use parts of the Russian 130 mm M-46, but are upgraded to 155 mm. It has been confirmed that Uganda took delivery of three ATMOS 155 mm systems in 2005.

This is the Romanian version of ATMOS and was first shown late in 2003 and is installed on a Romanian 6 × 6 truck chassis.