Kobelco RK250-3 (Panther 250)

The Kobelco RK250-3 is a compact and versatile 25-ton rough terrain crane, designed for efficient lifting in confined job sites and rugged environments. With its robust build, reliable drive system, and flexible boom and jib configurations, it is well-suited for infrastructure projects, urban development, and general construction applications.

The crane features a 4-section, hydraulically telescoping boom ranging from 9.3 to 30.6 meters, offering a strong and stable platform for medium-duty lifts. At maximum boom extension, the crane can lift 1,000 kg at 21.0 meters, and up to 25,000 kg at 3.5 meters radius using an 8-part line. In addition, the crane is equipped with a two-stage jib measuring 5.7 or 12.0 meters, which can be mounted with offset angles of 5°, 25°, or 45°, increasing its maximum lifting height to 43.8 meters.

Lifting operations are driven by high-performance winches that achieve 107 m/min (high speed) or 85 m/min (low speed) on the main winch and 106 m/min / 85 m/min on the auxiliary winch (at the 4th layer). The hook block can be configured with 100 kN (10.2 t), 45 kN (4.6 t), or 30 kN (3.0 t) ratings depending on the line pull requirement, utilizing an IWR 6C x F6 (22×7+0) spin-resistant wire rope.

The boom system includes fully synchronized telescoping using a double-acting hydraulic cylinder, allowing safe and smooth boom extension under load. Slewing is continuous 360°, powered by a hydraulic motor and planetary reduction gear, with a slewing speed of 2.0 rpm. Boom elevation ranges from –0.8° to 82°, controlled by a hydraulic cylinder, with a raise time of 47.6 seconds and lowering in 38.0 seconds.

Mounted on a 4×4 rough terrain chassis, the RK250-3 is driven by a Mitsubishi 6D16T, a 4-cycle, 6-cylinder turbocharged diesel engine, outputting 168 kW (220 PS) at 2800 rpm with a torque of 637 Nm at 1600 rpm. It features a powershift transmission with 6 forward and 2 reverse speeds, including Hi/Low range switching for hill-climbing or heavy-load conditions. The drivetrain offers selectable steering and driving modes with normal (front axle only), clamp, crab, and rear steering, supported by full hydraulic power steering with emergency backup.

The RK250-3’s hydropneumatic suspension and wide outrigger span (up to 5.1 m front/rear) provide excellent stability on uneven ground. The crane can operate with three outrigger extension widths: 6.3 m (max), 5.1 m (mid), and 3.8 m (min), with jack stroke of 0.60 m. The total vehicle weight is 26,500 kg, with balanced front and rear axle loads. It can travel at a maximum speed of 49 km/h, and climb grades up to 63% (tanθ = 0.63). A minimum turning radius of 5.4 m enables effective maneuvering in constrained spaces.

The operator cabin is ergonomically laid out with multi-display AML (Automatic Moment Limiter), engine and hydraulic status monitoring, boom angle indicator, and load charts for safe and informed operation. Additional safety devices include over-wind cut-off, hook safety latch, outrigger interlocks, and boom elevation slowdown protection.

In summary, the Kobelco RK250-3 is a compact, highly maneuverable 25-ton rough terrain crane that combines reliable lifting performance with ease of transport and operation. Its hydraulic efficiency, strong boom design, and advanced control systems make it a dependable choice for general construction and lifting tasks across a variety of terrain conditions.