SR7508 Drill Motor

The ultimate for professional use.

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SR7508 Drill Motor

SR7508 Drill Motor

The SR75 is an advancement of the SR-drive Drill Motors. Adjusted to the 400 V three-phase mains it offers power of 7.5 kW with a weight of only 19.5 kg.
Especially for professional use this drill motor sets standards that can not be reached with conventional motors.


SR Motor

The complete novel motor is based on the principle of the switched reluctance motor (SR = switched reluctance). The stator is very robust but simple. The rotor exists of a shaft on which there are strung several single steel laminations. This allows the motor to work without any turning windings or short circuit rotor and also without commutator and wear-affected carbon brushes. The motor saves resources, it consists almost only of steel and copper.
The commutation (alternating currenting of the stator poles) is managed by the electronic power which gets its orders from a microcomputer. The speed over the whole capacity range is almost constant, therefore the drill start is made easier, the wear is reduced and the efficiency of the drill bit is increased. 
Besides the six power speeds (nominal speed and high speed) it offers the user also three more lower motor speeds that are preferably used for drill starts of larger  diameters. 

Motor protection

The motor current is controlled corresponding to the requirements and limited to the maximum. Therefore it cannot be overloaded.
Via thermal protective switches the actual temperature of the motor and the electronic power is registered and if deemed necessary will be switched off safely. This allows the motor and power to be protected directly against thermal overload which may occur on insufficient cooling.

3-Speed Gearing Unit

The SR75 has a very solid gear with wide drilling range (see technical data) on favorable adaption of speed and torque to the respective drilling diameter. Especially mentionable is here the very high torque of 628 Nm in the first gear. (Constant torque)

Oil Bath Lubrication with Oil Pump

Optimal gear lubrication on high efficiency, long lifetime and low maintenance expense. The very efficient oil pump that is already used in the DK32 and DK52 is responsible for an optimal lubrication in all positions of use.

Safety Clutch

Due to the new type of motor fitted with a novel multi flange coupling which protects the operator, the tools and the motor against high mechanical overload. The higher number of friction surfaces guarantees a nearly constant releasing torque even after a few hundred overload cycles. Through the limiting of the torque by the motor management the wear out of the clutch is extremely low.

Water Cooling

The motor and electronic power is optimally cooled by a water cooling system that is patented and already used successfully in the DK42, DK52 and the SR 35. At this the water flows controlled through the interspace between the motor case and the case sleeve. Through this arrangement the electrical part is completely separated from the cooling and therefore the electrical safety is guaranteed.

Metal Case

The skin is completely made of aluminum. Therefore the SR75 is very robust, thermally stable and prepared for outstanding professional use. The casing is protected at the sensitive sides by a surrounding carrying handle.


The operating hours counter which is integrated in the micro controller allows for 300 hours of permanent use. Then the operator will be notified to maintain by only starting, when the start button is pressed three times.

The SR75 Jumbo is not only very strong and robust, but also water protected. With proper use water cannot enter the inner workings enabling the drill to be used upwards in a vertical position (overhead drilling) without any further precautions.


Technical Data

Voltage 400 3~
Current 15A
Power 7500W
Output Power 5700W
Motor Speed 1* /min 60/115/175
Motor Speed 2 80/160/250
Motor Speed 3 100/195/300
Length 620mm
Weight 19.5kg
Drilling Diameter 150-900mm
Tool Fixture M33/3
*These gears are power-reduced


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SR7508 Drill Motor

SR7508 Drill Motor