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GMN FE 8000 Sprag Clutch for eVTOL Innovation

eVTOL aircraft with city background

Executive Summary

GMN Bearing USA is a super precision component supplier of GMN German-manufactured bearings, clutches & seals. We are focused on improving the Electric Vertical Take Off and Landing (EVTOL) industry, helping to improve two very important aspects to clutch performance: torque output and longevity.  Through our exclusive FE 8000 Sprag Clutch design, GMN can help improve torque output of similar style clutches as well as extend longevity so manufacturers & passengers can get more out of their aircrafts.

Read on to learn how this expertly designed, highly engineered component can offer up to twice the torque and life expectancy of other brands.

Benefits of Integrating GMN Clutches into Your eVTOL

GMN Sprag Clutch - FE 8000

In an EVTOL, battery life as well as wear on internal components are especially important factors for not only profitability but more importantly, safety. That’s why the GMN FE 8000s series clutch is so vital to the industry. Implementing our clutch within your design will allow your motor and blade assembly to free wheel should a motor failure present itself. Why is that important? Allowing the motor/blade assembly to free wheel allows the blades to rotate without creating drag on the motor allowing the aircraft more time and distance to land safely.

One way to decrease drag and increase battery longevity is to decouple one or more of the motors when it is not required. This enables the additional motors to be disconnected and not further drain the battery(s) when the aircraft is coasting, while relying on one motor to maintain speed. Likewise, decoupling any unused drive train components will reduce the overall drag on the system. Less drag means less battery consumption which extends longevity per charge.

Another benefit to the GMN FE 8000 is its versatility, more recent eVTOL technology has incorporated smaller more compact-sized motors and because of GMN’s simple yet effective sprag clutch design, it can output twice as much torque allowing you to utilize a smaller size to fit your torque requirements in addition to saving space and weight.

What makes a Sprag Clutch the best design for eVTOLs?

Now that we have introduced the concept of how and where GMN sprag clutches can be used in eVTOL aircrafts, let’s examine why GMN’s design outperforms the rest.

GMN Sprag Clutch animation

Sprag Clutches are designed to transfer torque when the input rotation forces the sprags to engage. The sprags themselves are taller than the radial gap between the inner & outer races in which the sprags engage. The sprags are highly engineered & tightly controlled curved surfaces on the top and bottom and use a spring to keep them in constant contact with the mating races. When the input RPM decreases below the output RPM, the frictional force generated by the engaged sprags is released and the surfaces begin to slip allowing the system to freewheel.

Not all sprag clutches (aka, “insert elements”) are created equal. There are several factors that make this clutch a stand-out for eVTOL technology:

  • High torque capacity – The GMN FE 8000 has more sprags in its design than most other sprag clutches on the market. This key characteristic means GMN sprag clutches consistently have up to double the torque capacity. This equivalates to possibly using a smaller size clutch for your torque needs. More torque could mean a higher safety factor for your design.
  • Unique sprag curvature – GMN’s distinctive geometric design of the cam sprag is a “non-lift-off design". At a high rotation speed, centrifugal force will produce a pressing torque on the sprags, no matter how fast the spooling speed. This means there are no RPM limits!
  • Single cage design – Rather than a dual cage, a single cage supports the components and allows for an increased number of sprags over other brands. GMN's clutches also operate directly against the system shaft and housing, not requiring complex mating surfaces.
  • No drag clips – Some sprag manufacturers use drag clips to prevent the sprags from rotating too fast and lifting off. This creates extra wear on the inner sprag surfaces. Because GMN sprags don’t have to worry about lift off, there is no need for drag clips, resulting in much less wear.
  • Angle of twist One of the most important features of any sprag clutch is the rotational distance required for the sprag to engage, better known as the twisting angle. For GMN clutches, the twisting angle is typically under 3° for nominal torque values, but if the torque is small that twisting angle can be close to 0°. Relative to other clutch mechanisms, even 3° is considered quite low.

Angle of Twist diagram

Depending on your Electric Vehicle design, GMN Sprag Clutches may be the perfect solution for helping to increase your battery life & time in the sky—all while also not sacrificing performance.

Learn more about the markets & applications we serve

Let’s Talk!

Let’s see if GMN sprag clutches can be the game-changing component in your eVTOL design. GMN Bearing USA’s Mechanical Engineers are here to learn more about your EV dreams & how GMN Sprag Clutches can give you the boost to set you apart from the pack!

Contact us today to review your specific requirements & we can discuss an application evaluation!

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