Hydraulic jar with mechanical latch is a double acting jar designed to deliver hydraulic delay when jarring up or down equipped with mechanical lock in each direction. The HJML incorporates a latch mechanism to keep the jar locked in the neutral position and eliminate unexpected jarring while tripping or racking back on the derrick.

The HJML is normally operated in the latched position to reduce unexpected jarring while drilling and eliminate movement between jar components increasing service life.
The HJML operates with a simple up and down motion and is not affected by torque.
Impact force is controlled by a metering device that ensures consistent delay times over the full range of operating temperatures