In the clutch, the driveshaft is screwed to the hub which has two flats that engage the inner plates. When the shaft turns, the inner plates turn, applying pressure through the friction plates to the outer plates. This drives the housing and output pulley through the torque pins. At the torque limit, there is slippage between the friction pads and plates. But torque is continually applied and can be varied by controlling the solenoid force.
In the clutch, the driveshaft is screwed to the hub which has two flats that engage the inner plates. When the shaft turns, the inner plates turn, applying pressure through the friction plates to the outer plates. This drives the housing and output pulley through the torque pins. At the torque limit, there is slippage between the friction pads and plates. But torque is continually applied and can be varied by controlling the solenoid force.

An asbestos-free friction clutch built by the Polyclutch Div. of Custom Products Corp., New Haven, Conn. (www.polyclutch.com), is configured such that dynamic friction exceeds static friction, so torque can be gradually applied. The electronically controlled device can change torque during operation, making it well suited for servomechanisms. The clutch can also slip intermittently or continuously. The axially loaded multiple-slip clutch uses several voltage-controlled solenoids that put pressure on the friction plates.

Because the clutch applies torque so smoothly, there are no sudden loads transmitted through the system, reducing shock. This makes it ideal for tension control on wire, film, thread, and paper, says the manufacturer, It can maintain tension with no sudden surges, thereby minimizing breakage and allowing higher machine speeds.