Inertial Cap Tightener

The inertial cap tightener has a fractional horsepower motor that is suspended above the capping area and a flexible shaft that is attached to the chuck. The motor rotates the chuck to a speed of about 1700 R.P.M. The operator quickly presses the chuck against the cap, the rubber liner grips and rotates the cap. At the time the liner grips the cap, there is no drive power from the motor to the chuck. However, the high speed rotation and weight of the chuck have a large amount of inertial force. This force is transferred to the cap at the moment when the chuck contacts the cap. The force will tighten the cap, normally 1-1/2 rotations, and stop. Because the rotation speed is so high, it will seem to stop at contact. Because the rotation stops when the cap is tight, there is no pressure on the operator's wrist. To adjust the amount of torque, weights are added to or removed from the chuck.


  • Because rotation stops when the cap is tight, there is no force on the operator's wrist.
  • Models are available for operation in 110-120 and 220-240 volt, 50 or 60 hz, 1 phase electrics.
  • Explosion Proof models are also available.


  • Because there is not a constant drive on the chuck, the cap must have a smooth rotation during tightening.
  • Torque is set by adding and removing weights rather than a settable gauge.
  • The operator must take more care when pressing the chuck against the cap. Incorrect operation will cause incomplete tightening.
  • They are not well suited to metal caps on metal containers because of the high friction through the complete tightening.

Recommended Use:

Inertial cap tighteners are excellent for closing plastic caps on glass bottles, and plastic caps on plastic bottles with smooth necks. They work well on caps with diameters less than 60 mm, without lugs on the side.


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