|Wichita Clutch Inc., www.wichitaclutch.com|
Wichita Clutch, an Altra Industrial Motion company, Wichita Falls, Tex., borrowed technology from the aerospace industry to create composite water jackets for marine-duty, water-cooled clutches and brakes. Called AquaMaKKs, the units serve in offshore oil and gas platforms and in other heavy-duty applications such as mining, logging and forestry operations, and metal processing.
In the tensioning brakes, friction discs transmit torque by applying axial force from pneumatic, hydraulic, or spring-based actuators. The water jackets dissipate heat generated by the friction discs.
Within the jacket chamber, water runs in grooved concentric channels. A copper plate presses directly against the front of the jacket, forming a seal. Friction pads rub against the copper plate, which then transfers the heat to the water running through the jacket channels directly behind it.
Prior to developing the composite water jackets, clutches and brakes typically incorporated cast-iron water jackets. In salty marine environments, however, cast-iron jackets corrode and wear out quickly. Water with a high PH causes similar problems. Moreover, water-jacket iron tended to get hot during operation and acted like a radiator, heating up the rest of the clutch/brake parts as well.
In contrast, the new polymer jackets are insulators so adjacent parts don’t get warm. And they are as strong as the original iron parts. In tests, AquaMaKKs 36-in.-diameter composite water jacket withstood stresses more than four times greater than the maximum design load.
Units with composite water jackets also weigh much less than those with iron jackets, particularly important in mobile uses. For example, the 36-in. AquaMaKKs cast-iron water jacket weighs 375 lb while the composite version weighs no more than 96 lb.
This is significant in that each copper-friction disc requires two jackets, one on each side. Some units may have up to four discs and eight jackets. On larger 36-in.-diameter units, the copper plates themselves may be 3/8-in.-thick and weigh 114 lb. Thus on a unit with four discs and eight jackets, the weight of discs and cast-iron jackets can reach nearly 3,500 lb. With composite jackets, these components on the same unit weigh less than 1,200 lb.
Patents are pending for the composite materials and have been issued for the water-flow scheme which contributes greatly to the water jacket’s ability to dissipate heat. AquaMaKKs absorb up to 3,400 hp of heat, 35% more than the best units previously constructed for heavy-duty applications.
Composite water jackets easily retrofit into older AquaMaKKs units with iron water jackets as well as into other brands of clutch/brakes including older Kopper Kool models. There’s also a mounting bolt pattern and tooth profile designed to match Eaton models for interchangeability with no design changes.