nexen Air Champ Vs. Electric:
A Comparative Analysis
Pneumatic, or air, clutch/brakes are more efficient and economical than similarly sized electrical clutch/brakes because of one important variable; air's responsiveness to heat.
Air does not generate heat during clutch and brake engagement. Less heat allows greater torque transmission and efficiency. The greater thermal capacity of air-engaged clutch/brakes gives them a longer operating life. Since you can "get more work" out of an air-actuated clutch/brake, air proves to be more cost effective. It also costs less to run an air compressor than to operate an electrical unit.
Nexen Air Champ products have simple designs which demand fewer parts than electrical units. This represents a significant cost savings (up to 80% over electric clutch/brakes) in the long run.
Independent laboratory tests were conducted in 1995, by Huntington Engineering & Environmental Inc. of St. Paul, Minnesota. As a result of these, Nexen identified five key performance-related and cost-saving advantages of air-actuated clutch/brakes over electrical units of comparable size.
Response Time
Response time is the increment of time in seconds from the time the power is turned on or off at the control valve or power supply, to the time the clutch or brake responds with (full load) torque, or disengages and the torque begins to decay. The time to 100% clutch torque for the air clutch was 40% faster than for the electric clutch. The time to zero torque (brake on) for the air clutch was 42% faster than for the electric.
Torque Output
Tests focused on the torque output of NEMA 56 C-flanged air and electric clutch/brakes. The electric clutch transmitted only 45% of its rated torque. In comparison, the Nexen clutch transmitted up to 145% more torque under the same conditions, because it operated at a lower temperature. The higher operating temperature of the electric clutch affected torque fade as well.
Facing Life Comparison
The estimated facing life of air and electric units were determined in a calculation using:
- Volume of useable facing material
- Friction materials wear rate
- Work energy capacity
- Energy-per-cycle for a specific application
The results indicated that the Nexen clutch/brake had considerably more available facing volume, which translates into more horsepower-hours of work. While pads on the Nexen unit were worn away partially, they still had sufficient material left to create the required friction against the facings to start or stop the load on the output shaft. The pads on the electric unit, on the other hand, were worn so far down that there was metal to-metal-contact.
Thermal Horsepower
The test also revealed that the air clutch/brake consistently operated at lower temperatures compared to the electric unit. Nexen’s FMCBE-625 model has a rated thermal horsepower of 0.14. A comparable electric unit has a rated thermal horsepower of 0.10.
Repair Costs
A test to determine the number of cycles to failure was conducted, and the Nexen clutch/brake was the overwhelming winner, more than doubling the number of cycles achieved by the electric unit. Additionally, replacement part costs published by the manufacturers showed that the air unit is less expensive to repair.
Nexen engineers conducted additional analysis to acquire comparative data on energy consumption and unit cost savings. Here's what they found:
Energy Consumption
Using friction Facing Life comparison information gathered in a conveyor system application, along with power consumption data published in the electric clutch/brake manufacturer’s catalogue, it was discovered that the electric unit coil consumed 2.5 times more energy than the compressor that provided air to the Nexen Air Champ
Unit Cost Savings
Based on the manufacturer's published unit costs in 1995 price sheets, Air Champ clutch/brakes cost up to 10% less than comparable electric units.
| Model | Static Torque (lbs) | Response Time (sec) | Average Housing Temp. | No. of Cycles to Failure |
| Nexen | Clutch: 297 Brake: 212 |
Clutch: 0.105 Brake: 0.120 |
134° F | 3,026,855 |
| Electric | Clutch: 74 Brake:137 |
Clutch: 0.240 Brake: 0.130 |
152° F | 1,281,700 |
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