Save your crusher motor from burning.

Why crushers burn out motors

A crusher is one of the toughest duties a motor can be asked to drive. The rotor, hammers or jaw assembly carry very high inertia, so the machine takes a long time to reach running speed. Feed is rarely uniform, stalls and jams are routine, and hard tramp material can lock the crusher in an instant. When the motor is coupled rigidly to all of this, it has no protection from any of it.

The damage comes from heat. A squirrel-cage motor started direct-on-line draws several times its rated current until it reaches full speed. Against the crusher's high inertia that starting period is prolonged, and the heavy current lingers — heating the windings far beyond a normal start. Frequent starts, repeated stalls and sustained overload pile more heat on top, and eventually the insulation gives way and the windings burn.

What a fluid coupling changes

A Fluidomat hydrodynamic fluid coupling sits between the motor and the crusher and transmits power through oil rather than a rigid mechanical link. That single change addresses every one of the failure modes above.

• No-load motor start. At rest the coupling lets the motor run up to speed almost unloaded, so it reaches full speed quickly and the high starting current decays fast — the windings are spared the prolonged heating that a direct-coupled start causes.
• Smooth, controlled acceleration. Once the motor is up to speed, the coupling fills and uses its pull-out torque to accelerate the heavy crusher progressively, instead of forcing the motor to drag the whole inertia from standstill.
• Built-in overload protection. The coupling can only transmit a limited torque. If the crusher stalls or jams, it slips rather than passing the stall straight through to the motor — the motor is never asked to carry more than a safe load, so it does not overheat and burn.
• Shock absorption. Sudden impacts from tramp material or uneven feed are cushioned in the oil film rather than transmitted as torque spikes to the motor shaft, bearings and the rest of the drive train.

The result for the drive

With a Fluidomat coupling in the line the motor starts cool, never sees a stall as a direct mechanical load, and is isolated from impact. Starting current is lower and shorter-lived, which also eases the supply and switchgear. The crusher itself accelerates smoothly and runs with less vibration, while the motor — the most expensive and disruptive component to replace — is protected from the overheating that would otherwise burn it out.

Proven on crusher duty worldwide

Fluidomat fluid couplings have been applied to crusher drives across a wide range of plants and industries. For applications that also need stepless speed variation, Fluidomat SC scoop-control couplings have been supplied internationally — including to customers in Canada — for crusher duty, combining the same motor protection with controllable crusher speed. The principle is consistent across every installation: protect the motor, smooth the start, and let the coupling absorb the abuse a crusher hands out.