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PLOKE MJP and RPB are characterized by the fact that they are extremely easy to handle and the desired pretensioning force – no matter how large – is basically always achieved with simple hand tools. Due to the high tightening torques, however, high-performance tools must always be used in order to avoid tool breakage and the resulting possible personal injury.

Torque wrenches

Torque wrenches are the tool of choice for pretensioning or also loosening Multi-Jackbolt Pretensioners.

These simple hand tools allow effortless, controlled and precise generation of the desired tightening torque on the Jackbolts and thus the achievement of the desired preload force. 

We will be happy to supply you with the torque wrenches that matches your MJPs or advise you on the selection and procurement of the appropriate tool. Contact us!

Note: Even when using impact wrenches, the last tightening round (» see Manual, paragraph 1.4 Pretensioning, fifth) must always be carried out by hand with a torque wrench!


For pretensioning – even with manual torque wrenches – always use extra strong sockets for impact wrenches (Impact Socket). Suitable sockets are included in the scope of delivery, others are available at any time. Contact us!

Warning: Only use tools that are in perfect condition. The tightening torques of the Jackbolts are very high and cannot be compared with normal screws.

Impact wrenches

Modern cordless impact wrenches produce high torques and provide good support for pretensioning MJPs (» see Manual, paragraph 1.4).

Cordless impact wrenches used must achieve approximately three times the power of the recommended tightening torque. The following dimensions are recommended:

  • 3/8” up to 70 Nm tightening torque
  • 1/2” up to 200 Nm tightening torque
  • 3/4” over 200 Nm tightening torque

Pneumatic impact wrenches should also be able to produce at least three times the recommended tightening torque of the Jackbolts. Heavy-duty industrial impact wrenches – or, for the highest clamping torques, high-performance impact wrenches – offer good service here.

Please also note our recommendations in the Manual, paragraph 3.3 Impact wrenches.

We will be happy to supply you with the impact wrench that matches your MJPs or advise you on the selection and procurement of the appropriate tool. Contact us!



The Balancer is an easy-to-use assembly aid for effortless installation of large heavy Pretensioners on the main thread.

"Top-Down-Balancer" version
Facilitates precise horizontal alignment and effortless screwing on of large heavy MJPs onto the main thread when mounting from above.

"Down-Top-Balancer" version
For "overhead" installation of large heavy MJPs, e.g. Kaplan turbines.
Thanks to the three weight arms, the MJP can be precisely aligned horizontally, and the ball-bearing support ring then allows the nut to be effortlessly screwed onto the main thread from below.

For the procurement of a Balancer or the use within the scope of one of our services such as assembly support, please contact us.