A more powerful motor does not by itself make the crusher do more work; but when the crusher is overloaded, instead of stalling it keeps pushing with greater force. In a sense the old motor acted as a limit protecting the body; when the power rises this limit disappears and the force is passed on to the body, shaft, bearings and flywheel.

DRG-315M-6 90 kW 1000 rpm cast iron frame DRG three-phase motor – increasing crusher motor power

How does motor power turn into force?

With the flywheel speed unchanged, shaft torque is directly proportional to power. For example, going from 90 kW to 132 kW increases the torque that can be delivered to the crusher shaft at the same speed by about 1.47 times. If the crusher was designed for the old power, the shaft diameter, eccentric, bearing housings and jaw or rotor connections may not have been calculated for this extra torque.

Parts to be questioned

  • Cast body or welded plates: fatigue cracks, traces of earlier repairs
  • Eccentric shaft and bearings: are the bearing type and size suitable for the new torque?
  • Toggle plate on a jaw crusher: the part that breaks under overload to protect the body must not be reinforced carelessly
  • Flywheel and pulley: are the number of belts and grooves enough for the new power?
  • Base and anchoring: heavier motor and higher belt forces

Is capacity really limited by the motor?

If the old motor’s current does not run close to the nameplate value during crushing, the bottleneck is elsewhere: irregular feeding, worn jaws, the setting gap or screen capacity. In that case adding power brings cost but no extra tonnage. An upsizing decision should not be made without measuring current and capacity.

Whose approval is needed?

The crusher manufacturer or a competent mechanical engineer should assess the body and shaft calculations. On the motor side, the frame size, shaft diameter and base holes change with the new power; with the motor comparison tool you can see the dimensional difference between the two ratings.

Once approved, suitable options can be reviewed on application pages such as cone crusher motor and among the cast iron models in the shop.