Two of the most popular magnetic particle clutches from Ogura have been redesigned to improve performance for a variety of tension and torque control applications. The clutch now has a faster response because of a new optimized internal flux path design. In addition, this new, more efficient flux path allows for the clutch to use a smaller coil. The new coil is about 30-40 percent lower in wattage than the previous design, but this smaller coil is still able to generate the same torque as previous models. (35 in lbs for size 40 and 71 in lbs for the size 80). The smaller coil also reduces the operational temperature of the clutch reducing heat in the bearings which can lead to longer overall clutch life. For applications that require even greater heat dissipation, an optional forced air cooling chamber has been added to both the size 40 and 80. Only 7.5 psi is required to produce a significant increase in heat generation. Both units have an approximate 70 percent increase in heat dissipation. The 40 is increased from 70 watts to 120 watts and the 80 increases from 90 watts to 160 watts. Typical machinery applications that can benefit from these new designs are testing machines for motors, tension control applications, packaging equipment and test machinery where a simulation of load would be required.