Liebherr Mining Equipment Co. has redesigned its 360 ton T 282 mining truck into what it is calling the largest two axle diesel electric truck in the world. With a 400-ton payload, the new T 282B haul truck has an impressive 3650 hp option which the company said is 35% more powerful than its predecessor. This is in addition to the more than 200 improvements Liebherr said it made to the truck including an increased drive system capacity, larger tires, improved flame strength and greater overall cab size.

Going bigger was a matter of customer demand, said Francis Bartley, manager, research and development for the Newport News, Va.-based company. With applications in open mining such as coal, copper, iron, gold or diamond fields, the T 282B truck is targeted toward sites that are large enough to justify equipment of this size range, Bartley said. The truck measures 47.6 ft. long, 28.1 ft. wide and 24.03 ft. high, an increase from its 43.6 ft. x 27.7 ft. x 21.3 ft. predecessor launched in 1999.

The T 282B truck's new 3650 hp and 3500 hp option from DDC/MTU and Cummins is a significant step up from its predecessor's 2700 hp offering. Adding the extra horsepower, Bartley explained, was "to get the load to the dump site quicker--this is very important if you have a long uphill haul."

The DDC/MTU power options include the 90 L, 20-cylinder 20V-4000 engine rated 3650 hp at 1800 rpm and the 65 L, 16-cylinder 16V-4000 rated 2700 hp at 1800 rpm. Both diesels are four cycle, liquid cooled and equipped with a separate charge-air cooling circuit. The Cummins offering includes the 78 L, 18-cylinder QSK 78 diesel rated 3500 hp at 1800 rpm and the 60 L, 16-cylinder, QSK 60 engine rated 2700 hp at 1800 rpm. The engines are equipped with two Dba silencing LLC air cleaners monitored by cab gauges, a Rockford variable speed fan and a Mesabi radiator. The radiator, engine and alternator/rectifier are mounted on a separate rollout subframe to allow for easier maintenance, said Liebherr.

A brushless Siemens generator is directly driven off the engine, supplying the truck's electrical ac drive system. The ac power generated by the alternator is rectified into dc current and then converted into variable ac frequency by inverters. Separate inverters power each of the rear Siemens wheel motors, which Liebherr said allows for totally independent power to be supplied to either set of rear wheels. The motors drive an L+ S two-stage planetary gear set, resulting in a reduction ratio of 37.3:1 to 43.7:1, depending on application requirements.

Specific features of the ac drive include a slip/slide control which self-corrects the propel or retarding power to minimize rear-wheal splinting or sliding, steering support which automatically sends more torque and speed to the outside rear wheels when turning, two speed over speed which limits the truck's speed to preset conditions and load boxing which performs a system test of the electric drive at full engine power. Additional features include the SIBAS system monitoring program, anti rollback, brake blending and cruise control.

With a travel speed of 40 mph and a loaded operating weight of l,305,000 lb.--142,000 lb. more than its predecessor--the T 282B truck has two braking systems. The electrical retarding system shifts the relationship of the inverter to the wheel motors causing a generator effect from the motors. The motors generate up to 6030 hp of stopping power to slow the vehicle, expelling excess energy through fan-cooled resistors. When the truck has slowed to 0.5 mph from the electric retarding system, the Arvin-Meritor hydraulic brake system takes over using an engine-driven pressure-compensated piston pump. The accumulator actuates the front brakes, and a dual valve meters fluid to the brake calipers. The front brakes have one 48 in. diameter by 1.25 in. thick disc per wheel and five SCL 19 calipers per disc while the rear use two 28 in. diameter by 1 in. thick disc per wheel and one HDBC4225 caliper per disc. The rear service brakes are cooled by forced air, eliminating the need for an additional hydraulic cooling system, said Liebherr.

Each of the truck's axles is a Liebherr design accompanied by a nitrogen-over-oil suspension system. Using the nitrogen system on the truck "provides both spring action and damping," Bartley said. The front suspension is engineered with a double A-frame to allow the tire contact point to move up and down in a straight line, reducing tire deflection. The rear suspension uses two drag links, instead of the traditional nose cone, to send the force from the axle into the truck frame in a straight line, while two suspension stoats transfer the load directly into the wheels, removing any torque on the frame, Liebherr said.

Each wheel is also fitted with two Timken tapered miler bearings. The diameter of the front bearings is 25.35 in., while the rear bearings are 38.61 in. The truck has a 21.6 ft. wheelbase and is equipped with Michelin 56/80R63 tires.