Designed to endure
demanding enviroments


Doofor high frequency rock drill DF550L-EXT-2M
High performance hydraulic rock drill

Doofor DF550L-EXT-2M is a high frequency rock drill equipped with a hydraulic back hammer and two OMS-series rotation motors. The back hammer enables removing stuck drill steels from the rock and opening the threads of lines of drill bars in extension bar drilling. Two motors are optimal in broken or fissured rock conditions or when drilling mixed materials, such as soil or moraine.

The DF550L-EXT-2M has a low overhead of 84 mm from the drill center line. The rock drill has a separated flushing box. Flushing media can be water or air.

A flushing head can be turned upside down. Motor fittings direction can be specified (up, down or side). Accumulator valve direction can be specified. The rock drill is equipped with two OMS-series rotation motors. This enables continuous, a high torque of 1592 Nm and intermittent torque of 1900 Nm while still maintaining a high rotation speed.

Optimal maximum hole diameter for the DF550L-EXT-2M is 76 mm.

Technical Data
Nominal power class17 kW
Percussion pressure160 bar
(Percussion oil-flow)(95-120 litres/min)
Rotation motors2*160 cm3
Speed max.250 rpm
Torque (2*160 cm3)*1950 Nm
Oil flow *2*40 litres/min (max. 2*90 litres/min)
Gear ratio65/40
LubricationAir-oil mist, min. 200 g/h
Flushing air pressure5–7 bar
Flushing air flow4000 litres/min
Flushing water flow150 litres/min
Weight196 kg

76 mm

Optimal maximum
hole diameter

17 kW

Power class

R32, R38
T38, T45

Shank size



*) Numbers given are for two standard rotation motors (2*160 cm³) at an intermittent pressure of 260 bar [3770psi]. Motor options are 80 cm³, 100 cm³, 125 cm³ and 160 cm³. For professional use only as a component of a hydraulic system.

Feed force (pressure) must be adjustable during operation. Rotation torque and oil flow values given are for a typical rotation motor. See full brochure for detailed information on different rotation motors. Percussion pressure mentioned is a recommended value for a typical application. The product is intended for professional use by skilled personnel. Doofor reserves all rights for changes without prior notice.

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