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Clutches

Customizing Cam Clutches - 15937 Customizingcam clutches

Improved mechanical clutches transmit more power through a smaller, lighter envelope.

Ratchetclutches

Joseph Hungerford

Mechanical Clutch SpecialistEmerson Power Transmission, Ithaca, N.Y.

M

echanical clutch designs meet tough challenges in a multitude of industries: HVAC, bulk han- dling, packaging, pulp and paper, food and bev- erage, and especially off-highway and recre-ational vehicle applications. In these vehicles, manual transmis- sions use friction disc clutches to completely disconnect engines from their transmissions. On the other hand, automatic trans- missions need a way to let the engine turn while the wheels and gears inside a transmission come to a stop. For this task, automatic- transmission vehicles use a torque converter.A torque converter is a type offluid coupling that allows the engine to spin independently of the trans- mission. There are four main com- ponents inside its housing: pump, turbine, transmission fluid, and sta- tor. A stator resides in the center of the torque converter to redirect the fluid returning from the turbine be- fore it enters the pump again. Its usually aggressive blade design al- most completely reverses the direc- tion of the fluid, which dramatically increases torque converter efficiency. A ratchet clutch is a primitivedesign composed of two interlocking parts. A ratchet freewheels in one direction and locks up in the other.

Roller-ramp clutches

Outer raceoverrunning Outer racelocked

Cylindricalroller SpringSpring andplunger (The situation is the sameif the inner race is overrunning.) (A locked inner racegives the same result.) A roller-ramp clutch has ground rollers that operate on an inclined ramp forpositive engagement. Inner and outer races must be kept concentric and a compression style spring system is used to assist in roller engagement.