New Caterpillar® AD55B Underground Truck Boosts

Productivity, Operator Comfort and Serviceability

The new Caterpillar® AD55B articulated truck for underground mining replaces the AD55 and features more power and enhanced braking and retarding for faster speed on grade and greater productivity. The 55-metric-ton-capacity (60.5-short-ton-capacity) truck also has new components and layouts for greater reliability, superior operator comfort and easier maintenance.

The Cat® C27 ACERT®engine produces 805 gross horsepower, 19 percent more when compared to the previous model. Similarly, torque is up 30 percent. The result is a 20 percent increase in speed when fully loaded and ascending a 14 percent grade.

Automatic retarder control (ARC) also contributes to high productivity. It electronically controls retarding on grade to maintain optimum engine rpm and oil cooling for faster downhill hauls. ARC protects the engine from overspeeding, improves fuel efficiency, provides better control of the truck, increases productivity and frees the operator to focus on other tasks.

The Cat oil-cooled braking system combines the service, secondary, parking brake and retarding functions in the same robust system. Additional braking may be applied using the manual retarder or the brake pedal. The AD55B brake system provides a fast and predictable response for smooth operation.

The Cat seven-speed planetary power shift transmission features electronic clutch pressure control with controlled throttle shifting. The system reduces power train stress and clutch wear by controlling engine speed, torque converter lock-up and transmission clutch engagement during shifting. The result is exceptional shift smoothness and a more comfortable ride for the operator.

Enhanced operator comfort and safety

In addition to smooth transmission shifting, two variable-rebound suspension cylinders connected to an accumulator absorb road shocks before forces get to the truck frame for extended frame life and a smoother ride. The new engine itself contributes to operator comfort through reduced vibration and exhaust noise.

The AD55B operator station is ergonomically designed for total machine control in a comfortable, productive and safe environment. All controls, levers switches and gauges are positioned to maximize productivity and minimize operator fatigue. A fully adjustable suspension seat with adjustable armrests provides optimal operator comfort. Integral to the cab and frame, both the rollover protective structure (ROPS) and falling objects protective structure (FOPS) are resiliently mounted to the mainframe to isolate the operator from vibration for a more comfortable ride. An optional temperature-controlled, enclosed cab provides a quiet, comfortable working environment.

The AD55B cab has a safety interlock. If the operator fails to apply the park brake prior to exiting the cab, the interlock system will detect the absence of operator input and apply the park brake, neutralize the steering implements and transmission and command the engine control module to shut down the engine.

Easier maintenance

The AD55B incorporates a number of changes to make service faster and easier. For example, the transmission, engine and fuel filters are now located so that they can be changed easily from the ground. The air cleaner is located for easier access, and the radial seal air filters are easy to change, reducing time required for air filter maintenance.

Also, easy access to daily service points and ground level sight glasses simplify servicing and reduce time spent on regular maintenance and inspections.

To aid service work, a fold-up ladder provides easy access, and hand rails are standard. A bolt-on radiator guard allows faster access to the cooling system.

The AD55B has a number of features to keep costs down and availability high. For example, recommended service intervals are 500 hours. The modular power train allows technicians to remove and replace components in less time, and many components are shared with other Caterpillar machines, which can reduce parts inventory and help ensure parts availability.

For additional information about the AD55B underground mining truck-the largest in the Caterpillar line of underground trucks-customers should contact their local Cat dealer or visit the Caterpillar web site at

AD55B Underground Truck Specifications

Engine model


Gross power (SAE)

776/805 hp (579/600 kW)

Net power (SAE)

725/751 hp (540/560 kW)


7F/1R, electronic power shift

Nominal payload

60.5 tons (55 metric tons)

1Body cap. (std.dump)

35.2 cu yd (26.9 cu m)

Gross operating weight

231,485 lb (105 000 kg)

2Tunnel clearance height

16 ft 4 in. (5.0 m)

2Tunnel clearance width

16 ft 4 in. (5.0 m)

1SAE 2:1; additional dump bodies and an ejector body are available.

2Clearance dimensions are for reference only.

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