We sometimes get the question about how hot a clutch can get. Ogura GT series clutch brakes are installed on millions of residential and commercial riding mowers built by most of the world's leading brands. These electromagnetic type devices are mounted on the engine shaft and drive the cutting blades when 12V power is applied. When power to the clutch is turned off, the clutch disengages, and the brake helps to slow the blades to a stop.

The clutch actuates electrically, meaning the coil inside is what generates the magnetic flux to provide engagement. Coils inherently generate heat. The power that the clutch consumes is generally about 45-68 Watts. If the clutch is left powered on / engaged for an extended time, the surface temperature will normally rise by about 40C (72°F). So, if a coil is left on at 20C (68°F), the surface temperature will rise to about 60C (140°F). The temperature inside of the coil is higher. Every machine is different so the actual temperature will vary. Keep in mind that wind helps cool the clutch and the airflow around clutches can vary. Lastly, excess debris can hinder heat dissipation as well.

These clutch brakes are designed and built for running in these conditions. They have a high temperature epoxy around the coil. The coil wire insulation starts to degrade at 135C (275°F). The sealed bearings have a special fill of high temperature grease. By controlling the bore and outer diameter fits on the bearings, the bearing internal clearance is able to be tightly controlled as well.

Aside from the coil naturally heating to a saturation point, dynamic cycling also generates heat. While there is some allowance for clutch engagements, by limiting the engagement speed and the frequency of engagements, it will allow the clutch to cool between engagements. While temporary temperature spikes are ok, you will want to avoid sustained exposure in order to prolong clutch brake life.

Ogura GT series PTO clutch-brakes are made in a variety of configurations and typically mount on gas and diesel engines rated up to 40 HP. Bore sizes match the typical engine shaft sizes. Pulley sizes can vary based on machine requirements. Some have hub outputs to mount your own pulley, sprocket or coupling half. Clutch torque is rated up to 400 lb-ft on the larger units. These clutches typically operate on 12 or 24VDC.

Benefits of using an Ogura PTO clutch brake:

• Long life
• Safety
• Built for outdoor operation
• Many years of proven success
• For use with operator presence controls
• Available with a soft start controller
• Custom designs available based on minimum order quantities

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