Hydraulic/Mechanical Drilling Jars

This drilling jar is well suited for virtually all drilling operations. The jar was developed to overcome the usual shortcomings associated with purely hydraulic or mechanical jars, yet retain the advantages of both concepts. This jar combines our mechanical “safety” latch with a hydraulic delay sequence on the up jarring stroke. The down jarring stroke is achieved mechanically. To jar upward, overpull is applied to the drill string until the preset mechanical latch setting is overcome and the jar enters the hydraulic delay sequence. The desired overpull above free string weight is then taken as the jar continues to slowly open under hydraulic restriction (delay) with the drawworks brake applied. After the hydraulic delay, the jar enters the free stroke and the mandrel accelerates to the fully extended position creating a jarring impact. Simply lowering the drill string resets the latch. The jar is then ready for another jarring cycle or to resume normal drilling operations.

To jar down, the drill string is lowered until the compressive force applied to the jar exceeds the preset mechanical latch setting. The latch releases allowing the mandrel to accelerate to the fully closed position creating a downward jarring impact. Raising the drill string until free movement stops indicates the latch has reset. The jar is ready for another jarring cycle or to resume normal drilling operations.


  • Jar sizes range from 4 3/4" to 9 1/2"
  • Will not fire unexpectedly while drilling, tripping, making connections, or tagging bottom
  • No safety clamp or special handling procedures are required on the rig floor.
  • Less restricted jar placement in the BHA; the jar can be placed in tension, neutral, or compression.
  • Ideal for use in compression, as there is no need to wait for “bleed through” when tagging or picking up off bottom.
  • Ideal for use in directional or extended reach horizontal wells; the jar can be run in the lower BHA in compression or in the upper BHA in tension.
  • No special tripping or drilling procedures are required.
  • Linear latch is not affected by torque; ideal for use in high friction, directional and extended reach horizontal wells.
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