PDM/PDH Strand Jacks

A strand jack essentially comprises the lifting cylinder and two anchor heads (top anchor and bottom anchor). The strand cable is moved upwards or downwards by alternately opening and closing of the top and bottom anchor during the lifting stroke of the hollow piston. This creates the load lifting or lowering movement.

Our strand jacks are designed for strands with a diameter of 15.7 mm. An admissible force of 120 kN is allowed per strand.

We offer strand jacks with a nominal load of 200 to 6,400 kN and a lifting stroke of 500 mm. The series is designed to allow strand jacks for different rated loads to be easily combined.

Strand jacks with mechanical anchor heads (series PDM) are available for rated loads of up to 1,600 kN, and with hydraulic anchor heads (series PDH) for rated loads of up to 6,400 kN.

  Rated load
[kN]
Number
of strands
Pressure
[bar]
Stroke
[mm]
PDM-020
PDH-020
200 2 315 500
PDM-040
PDH-040
400 4 315 500
PDM-080
PDH-080
800 7 315 500
PDM-160
PDH-160
1600 14 315 500
PDH-320 3200 31 315 500
PDH-640 6400 61 315 500

Optimum strand guidance is guaranteed by hardened guide plates at the anchor heads and suspension. Telescopic strand guide tubes perform this function inside the hollow piston.

The basic equipment of the strand jack includes the following components:

  • Load holding valve
  • Connection for second strand jack
  • 2 electrical pressure sensors to measure pressure on the piston and retraction side
  • Linear potentiometer for piston stroke
  • One linear potentiometer each for the wedge-seating stroke of the anchor heads (series PDH)
The hydraulic anchor heads open and close the anchor wedges (by pressing them into the wedge plate). This is particularly beneficial for pulling operations in horizontal use.




PDP Hydraulic Pump Units

Every strand jack is supplied by a hydraulic pump unit. This allows hydraulic line lengths to be kept to a minimum. There are three different units using pumps with different delivery capacities. The pumps also supply the hydraulic anchor heads.

  Flow rate
[l/min.]
Motor output
[kW]
Pressure
[bar]
PDP-08 8 5,5 315
PDP-16 19 11 315
PDP-32 36 22 315


Standard equipment:
  • Return-flow filter with clogged filter indicator light at the control system
  • Oil level display at the oil tank (filling quantity and temperature)
  • Electrical cabinet with interface for the bus system and connection with manual control system

Optional equipment:

  • Electrical oil level display
  • Electrical oil temperature display
  • Oil tank heating
  • Oil tank cooling
  • Frequency converter for stepless flow rate

 

Control System

Operation of the strand jacks takes place centrally with the aid of a user-friendly control system. It visualizes up to 16 strand jacks on a display, so guaranteeing full control of the hydraulic pressure, piston stroke and anchor assembly status (open/closed). If required, the display can be supplemented by additional strand jacks. The central control system is connected by means of a bus cable to the individual hydraulic pump units and processes signals in real time.

The following operating modes are supported by the control system:

  • Set-up mode and pre-load stroke
  • Automatic lifting and lowering mode
  • Manual mode for corrections

The control system monitors the lifting or lowering mode. It is possible to select between pressure and path monitoring. If the prescribed limiting values are exceeded, the operator is warned and, if necessary, the current process is stopped in order to carry out the necessary corrections. In the automatic mode, the control system regulates the stroke and pressure automatically.

Accessories

We supply a series of accessories in order to simplify handling of the lifting equipment and the strands:

  • Transport cases
  • Strand guides
  • Hose packages
  • Uncoiling reels for strands
  • Strand dispensers
  • Anchors for fixed side
  • and many more