The SB 155/39 towed howitzer has been developed by the Fabrica de Artilleria de Sevilla, part of SANTA BARBARA, to meet the requirements of the Spanish Army for a weapon to replace its US-supplied 155 mm M114 towed howitzers.

In addition to the basic SB 155/39 towed howitzer, one other version is under development, with an auxiliary power unit (REMA) (first prototype completed in 1987).

The prototype began firing trials in March 1985. The SB 155/39 will be employed at brigade and division level for defensive and offensive action. By early 1997, four prototypes of this system had been completed but volume production had yet to start.

Some years ago SANTA BARBARA proposed a full-tracked self-propelled version of this weapon but this was never built.

The weapon has a conventional split trail and, to reduce its overall length for travelling or air transport, the barrel can be swung back through 180º and locked in position over the closed trails. The trails are of a welded box section with the spade folding up under either end. To assist in bringing the SB 155/39 into and out of action, a rubber-tyred wheel is mounted on the inside of each trail leg and these are swung up through 90º when the weapon is in the firing or travelling position.

When in the firing position the wheels are raised clear of the ground and the carriage is supported by a circular firing jack. Each main roadwheel has a hydropneumatic suspension system which is also used to lift the wheels clear of the ground when bringing the system into action.

The ordnance has a double-baffle muzzle brake, hydropneumatic recoil system and a vertical sliding breech mechanism. Elevation is from -5 to +70º with a traverse of 30º left and right. Elevation and traverse are manual with controls on the left side of the carriage. The goniometer has a magnification of x4 and can also be used as a telescope to engage armoured vehicles at close range.

Interior dimensions of the ordnance conform with those of the 155 mm FH-70 and M198 systems already in service in NATO. A power-assisted rammer is fitted as standard. Using charge 8, an HE projectile weighing 43.5 kg can be fired to a maximum range of 24,000 m. With a rocket-assisted projectile, range is increased to 30,000 m. SANTA BARBARA produces an HE projectile known as the SB-811 which carries a 10.5 kg warhead and has a range of 24,000 m.

With a well-trained crew a burst rate of fire of 4 rds/min can be achieved.

The SB 155/39 is towed by a 6 x 6 truck which carries the crew of six and ammunition. Maximum towing speed on roads is 80 km/h, 40 km/h cross-country.

This is essentially the standard towed howitzer with a 70 hp four-stroke diesel engine mounted on the forward part of the carriage which, via hydraulic motors, powers the roadwheels. In addition to propelling the weapon at a speed of 12 km/h, the engine also enables it to negotiate gradients of up to 30 per cent, to change position quickly after a few rounds have been fired to avoid counterbattery fire, and, in conjunction with the 6 x 6 truck, negotiate very rough terrain as it then has an 8 x 8 configuration.