Purpose: The Swivel Mount Shock Sub vibration dampener is a resilient coupling used between the drill and the drill pipe on top drive machines to dampen shock loads created by the bit action.
Shock and vibratory energy transferred between drill and bit are absorbed through a series of rubber bonded segments. The absorbed energy is released to the atmosphere in the form of heat.
- The pulldown or drilling weight to the bit is transferred through the segment rubber placed in shear.
- The rotational torque (or torsional loading) to the bit is transferred through the segment rubber placed in compressive loading.
- The accelerated changes in axial and torsional loadings are minimized by the segment rubber.
Construction: The MTI Swivel Mount Shock Sub consists of an element with upper and lower adapters and a packing assembly. The element consists of a number of segments, each having two drive lugs moulded together with rubber which are retained by the endplates.
The design of this unit includes a safety feature which assures that rotation may continue and retraction of drill pipe from the hole is possible even though complete rubber fatigue life has been reached.
When used: The shock absorber is most beneficial when drilling in fractured formations, intermittent hard and soft layers, or hard formation.
Benefits:
- Reduces drilling machine maintenance by dampening torsional and axial shock loads.
- Increases drilling rates by keeping bit in more uniform contact with formation. Allows use of more weight and higher rotary speeds in rough drilling areas.
- Increases bit life by dampening cyclical shock loading normally transmitted to the bit bearings and cutting structure.
- Decreases operator noise level by eliminating the metal to metal contact between rotary drive and drill pipe.
Operation: Normally, no modification of the drill is required and installation can be completed in a short time. On multi-pass drills where length is not critical, a saver sub is recommended for use between rotary shouldered connection and drill pipe.
Maintenance and Renewal: Minimal maintenance is required on an MTI Swivel Mount Shock Sub vibration dampener. The following "on the drill" procedures will, however, ensure maximum service life:
- Remove any oil and dirt accumulation by dry means.
- Check bolts for looseness and tighten if necessary.
- Check packing for air leakage and replace if necessary.
Rubber fatigue life will vary depending on drilling conditions and severity of application. After rubber fatigue, the elements can be returned to MTI for inspection and rubber remoulding.
Caution: It is recommended that the Swivel Mount Shock Sub be inspected during each drill maintenance period to ensure that all alloy bolts are tight. If bolt replacement is necessary, use equivalent alloy steel bolts.
Heavy duty shock absorber Models 40, 50, 75, 100, and 130 are each tailored to give optimum performance within a given operating range or down pressure as shown in the table. The elements incorporate eighteen segments, each consisting of two heat treated alloy steel drive lugs moulded together with rubber. These segments are retained by end plates to which the adapters fasten.
When ordering please specify:
- Drill make and model
- Upper adapter required
- Lower adapter connection required
- Drill steel outer diameter
- Average drilling weight used
