Hydraulic Precision Power Wrench

30.73 Tightens rail fastenings to an accurately controlled torque and provides an end-to-end documentation of every wrenching process.

  • Work output can be shown to conform to the regulations
  • High accuracy of wrenching every time
  • Automatic recording of every wrenching action
  • Great ease of use
  • No sleeper damage as may be caused by excessive torques
  • High tightening and loosening torque for eroded hardware
  • Nearly maintenance-free and always ready for use
  • Output of coded result log to USB drive
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Drive Air-cooled four-stroke engine
Type HONDA GX200
Output 4,1 kW at 3.800 U/min
Loosening/tightening torque 900 / 500 Nm
Torque up to 250 Nm
Transport position 1530 x 470 x 670 mm
Working position 2090 x 470 x 960 mm
Weight machine ~ 99 kg
Weight transverse travelling gear ~ 6 kg
Weight outrigger ~ 3,5 kg

How does the wrenching program compare planned to actual values?

Comparison control loop:

1 – Within milliseconds, the force transducer checks by how much the screw has been tightened at any time of the wrenching process and

2 – transfers the reading to the PLC.

3 – The PLC recognises the wrenching case with reference to the gradients it stores.

4 – The spindle speed is accurately set to achieve the final torque.


  • The machine stops automatically when the PLC detects the maximum torque of 250 Nm and that it has been applied within an acceptable time.
  • To save time, it calculates the speed for the next wrenching process.
  • Check the display to see whether wrenching has been completed correctly.
  • All captured data is logged including the status of every wrenching completed and/or every screw skipped.
  • In case a fault is displayed, the machine undoes the screwed joint and repeats the process.
  • As opposed to mechanical machines, final steps such as checking and re-tightening the screws is not required.

How does ROWRENCH P4 Rec loosen corroded, seized screws?

When loosening screwed joints, the torque is dynamically and linearly increased to up to 880 Nm. This is not only preserving the machine mechanism but also applying a high loosening torque which reliably tears off rusty screws of older K-type track fastenings. A process stored in the PLC can be chosen from the menu to loosen screws seized in loose W-type track dowels.

May I also check screwed track sections?

Since the PLC controls the dynamic process of 30.73 PSM, you are now among the first to check the torque of previously tightened screws without having to completely unscrew them as had to be done hitherto. Again, all torques measured in the process are logged. This method is mainly intended to quickly show that the hardware in older tracks is still tight in conformity with regulations.

What is screwing directive Ril. 824.5050 about?

Directive Ril. 824.5050 published by Deutsche Bahn on how to produce uninterrupted tracks and on the bracing of rail fastenings aims for a reliable connection between rails and sleepers while minimising damage to the sleepers.


Pursuant to the Directive, a rail is correctly fastened if the set-point geometric bracing (gap size ≤ 0.5 mm) is achieved without exceeding the maximum permissible torque of 250 Nm.


Every hundredth sleeper (if fastened by a hydraulic power wrench) or every twentieth sleeper (if fastened by a mechanical power wrench) is to be checked by using a torque spanner. Conformity with the Directive has to be shown in writing.


The Directive also provides supportive arguments in case of conflicts. If there is a conflict about the cause of sleeper damage, the logging of wrenching processes supports the building contractor in its position against the client because an excessive torque can be ruled out as the cause of a cracked sleeper.

Does a screwed joint have to be checked for conformity with Ril. 824.5050?

No. ROWRENCH P4 Rec meets all standards set by DB Directive 824.5050. DB has therefore decided to exempt Robel's Precision Power Wrench from the otherwise compulsory verification of every hundredth or twentieth screw.

Hydraulic Precision Power Wrench

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